Journal articles on the topic 'Combined CFD-Experiment'
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1
Xie, Changxiong, Heng Su, Jun Yang, and Zhongjing He. "Design and Analysis of Combined Valve Spool with Linear Flow Coefficient." Journal of Engineering 2022 (June 13, 2022): 1–7. http://dx.doi.org/10.1155/2022/6006810.
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The orifice flow model is generally established based on the turbulent state, and the flow discharge is considered to be a constant value. In fact, the flow discharge has obvious nonlinearity under the condition of small opening and small pressure difference of the valve port, which makes the electro-hydraulic servo system more difficult to control. In order to improve the nonlinearity of the flow discharge, the paper designed different spool profile, such as the arc combined spool profile, the power curve combined spool profile, the index curve combined spool profile, and the mixed curve combined spool profile, and analyzed the flow discharge through CFD simulation and experiment. The results show that the flow discharge of the mixed curve combined spool is more linear and the residual sum of squares is the smallest, which is 2.56 × 10−3 under CFD numerical simulation and 3.26 × 10−4 under experiment. The combined spool has better linear characteristics, which can improve the control performance of the electro-hydraulic servo valve.
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Li, Hui Yuan, Ming Xu, and Chao Wu. "Flow Field Analysis and Experiment Study on Air Losing of Hydraulic Retarder." Advanced Materials Research 378-379 (October 2011): 94–97. http://dx.doi.org/10.4028/www.scientific.net/amr.378-379.94.
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Based on application characteristic of hydraulic retarder in combined braking, the generant mechanism of air losing is analyzed, by adding baffle-plate setting, air losing is reduced. Using CFD technology, the ameliorative hydraulic retarder is studied contrastively, and the results are in good agreement with the experiment.
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Feng, Jing-an, Xiao-qi Tang, Wei-bing Wang, Rui Ying, and Ting Zhang. "A Combined Method in Parameters Optimization of Hydrocyclone." Mathematical Problems in Engineering 2016 (2016): 1–13. http://dx.doi.org/10.1155/2016/9209362.
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To achieve efficient separation of calcium hydroxide and impurities in carbide slag by using hydrocyclone, the physical granularity property of carbide slag, hydrocyclone operation parameters for slurry concentration, and the slurry velocity inlet are designed to be optimized. The optimization methods are combined with the Design of Experiment (DOE) method and the Computational Fluid Dynamics (CFD) method. Based on Design Expert software, the central composite design (CCD) with three factors and five levels amounting to five groups of 20 test responses was constructed, and the experiments were performed by numerical simulation software FLUENT. Through the analysis of variance deduced from numerical simulation experiment results, the regression equations of pressure drop, overflow concentration, purity, and separation efficiencies of two solid phases were, respectively, obtained. The influences of factors were analyzed by the responses, respectively. Finally, optimized results were obtained by the multiobjective optimization method through the Design Expert software. Based on the optimized conditions, the validation test by numerical simulation and separation experiment were separately proceeded. The results proved that the combined method could be efficiently used in studying the hydrocyclone and it has a good performance in application engineering.
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Park, Donggeun, and Jong-Hyeon Lee. "Feasibility Evaluation of Computational Fluid Dynamics Approach for Inhalation Exposure Assessment: Case Study for Biocide Spray." Applied Sciences 11, no. 2 (January 11, 2021): 634. http://dx.doi.org/10.3390/app11020634.
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Consumer products contain chemical substances that threaten human health. The zero-dimensional modeling methods and experimental methods have been used to estimate the inhalation exposure concentration of consumer products. The model and measurement methods have a spatial property problem and time/cost-consuming problem, respectively. For solving the problems due to the conventional methodology, this study investigated the feasibility of applying computational fluid dynamics (CFD) for the evaluation of inhalation exposure by comparing the experiment results and the zero-dimensional results with CFD results. To calculate the aerosol concentration, the CFD was performed by combined the 3D Reynolds averaged Navier–Stokes equations and a discrete phased model using ANSYS FLUENT. As a result of comparing the three methodologies performed under the same simulation/experimental conditions, we found that the zero-dimensional spray model shows an approximately five times underestimated inhalation exposure concentration when compared with the CFD results and measurement results in near field. Additionally, the results of the measured concentration of aerosols at five locations and the CFD results at the same location were compared to show the possibility of evaluating inhalation exposure at various locations using CFD instead of the experimental method. The CFD results according to measurement positions can rationally predict the measurement results with low error. In conclusion, in the field of exposure science, a guideline for exposure evaluation using CFD, was found that complements the shortcomings of the conventional methodology, the zero-dimensional spray model and measurement method.
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Park, Donggeun, and Jong-Hyeon Lee. "Feasibility Evaluation of Computational Fluid Dynamics Approach for Inhalation Exposure Assessment: Case Study for Biocide Spray." Applied Sciences 11, no. 2 (January 11, 2021): 634. http://dx.doi.org/10.3390/app11020634.
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Consumer products contain chemical substances that threaten human health. The zero-dimensional modeling methods and experimental methods have been used to estimate the inhalation exposure concentration of consumer products. The model and measurement methods have a spatial property problem and time/cost-consuming problem, respectively. For solving the problems due to the conventional methodology, this study investigated the feasibility of applying computational fluid dynamics (CFD) for the evaluation of inhalation exposure by comparing the experiment results and the zero-dimensional results with CFD results. To calculate the aerosol concentration, the CFD was performed by combined the 3D Reynolds averaged Navier–Stokes equations and a discrete phased model using ANSYS FLUENT. As a result of comparing the three methodologies performed under the same simulation/experimental conditions, we found that the zero-dimensional spray model shows an approximately five times underestimated inhalation exposure concentration when compared with the CFD results and measurement results in near field. Additionally, the results of the measured concentration of aerosols at five locations and the CFD results at the same location were compared to show the possibility of evaluating inhalation exposure at various locations using CFD instead of the experimental method. The CFD results according to measurement positions can rationally predict the measurement results with low error. In conclusion, in the field of exposure science, a guideline for exposure evaluation using CFD, was found that complements the shortcomings of the conventional methodology, the zero-dimensional spray model and measurement method.
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Meng, Jin Long, and Zhao Qin Yin. "Numerical Simulation on the Parallel Combined Nozzles of Mini/Micro Gas Flow Standard Device." Advanced Materials Research 472-475 (February 2012): 2000–2003. http://dx.doi.org/10.4028/www.scientific.net/amr.472-475.2000.
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The flow characteristics in mini/micro sonic nozzles have been studied in this paper using the computational fluid dynamics (CFD) method. The result shows that the flow rate of the parallel combined nozzles is not equal to but smaller than that of the sum of the nozzles. The reason is the each effect of the air after nozzles, which changes the flow field parameters .The more number of the parallel combined nozzles, the bigger error exits between actual flow rate and that of the sum of the nozzles. The result is consistent to the experiment. The study also shows the smaller of the nozzle’s diameter, the bigger error exits.
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Long, Christopher A., Alan B. Turner, Guven Kais, Kok M. Tham, and John A. Verdicchio. "Measurement and CFD Prediction of the Flow Within an HP Compressor Drive Cone." Journal of Turbomachinery 125, no. 1 (January 1, 2003): 165–72. http://dx.doi.org/10.1115/1.1516195.
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In some gas turbine aeroengines, the HP compressor is driven by the H.P. turbine through a conical shaft or drive cone. This drive cone is enclosed by a stationary surface that forms the supporting material for the combustion chambers. Air used to cool the turbine blades is directed into the space around the drive cone, and a major concern to an engine designer is the temperature rise in this air due to frictional dissipation and heat transfer. This paper presents results from a combined experimental and CFD investigation into the flow within an engine representative HP compressor drive cone cavity. The experimental results show similarities in flow structure to that found in classic rotor-stator systems. Both 2-D and 3-D CFD simulations were carried out using the FLUENT/UNS code. The 3-D model which included the actual compressor blade tip clearance gave the best agreement with the experimental data. However, the computational resource required to run the 3-D model limits its practical use. The 2-D CFD model, however, was found to give good agreement with experiment, providing care was exercised in selecting an appropriate value of initial tangential velocity.
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Tang, Yi, Jing Xie, Chen Miao, Jin Feng Wang, and Yi Zheng. "Theoretical Study and CFD Simulation of Airflow Distribution through a Cold Store." Applied Mechanics and Materials 170-173 (May 2012): 3543–49. http://dx.doi.org/10.4028/www.scientific.net/amm.170-173.3543.
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Recently, the quantity of the cold store has been increased quickly. It is a key point to improve the uniformity of airflow field to the cold store. In this paper, a model of simulating cold store by computational fluid dynamics (CFD) was introduced. Simple algorithm combined with Boussineq assumption was used and turbulent equation combined with standard wall function was applied to define the flow of air in the cold store. Both the structured mesh and unstructured mesh to cold store model were simulated. The simulation methods of airflow in a cold store between three-dimension (3D) technology and two-dimension (2D) technology were also discussed. The experiment was validated and proved that unstructured grid was in better agreement with the result of experiments and it was gotten that the three-dimension (3D) technology had a higher accuracy in simulation of airflow distribution. The airflow distribution in the vertical plane and horizontal plane in cold store were gotten, respectively.
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Guntur, Srinivas, Niels N. Sørensen, and Scott Schreck. "Dynamic Stall on Rotating Airfoils: A Look at the N-Sequence Data from the NREL Phase VI Experiment." Key Engineering Materials 569-570 (July 2013): 611–19. http://dx.doi.org/10.4028/www.scientific.net/kem.569-570.611.
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This paper presents an investigation on the combined effect of dynamic stall and rotational augmentation on wind turbine blades. Dynamic stall and rotational augmentation have previously been studied independently. The NREL Phase VI experiment was one large scale experiment that recorded 3D measurements on rotating and pitching airfoils, and using some these data the behaviour of the unsteady CL-α polars under the influence of rotation is investigated. Unsteady DES CFD computations of the Phase VI rotor in axial operation and continuous pitching conditions (reproducing conditions similar to the N-sequence experiments) for select cases have also been carried out using the in-house flow solver EllipSys3D. The resulting set of CL-α curves for the airfoils in rotation operating at various values of the frequency, the mean, and the amplitude of the angle of attack resulting from the CFD computations as well as those from the experiments are presented and discussed. Qualitative differences between dynamic stall occurrence on rotating and stationary airfoils are highlighted, procedures employed to extract the mean angle of attack from the available experimental data are discussed, and comments are made on the application of dynamic stall models in conjunction with 3D augmentation models on the rotating wind turbine blades.
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Park, Jung Ha, Seol Hui Park, Jung Hoon Ju, and Jin Chul Park. "An Experiment and CFD Simulation for the Application of a Wind Power System Combined with Exhaust in Super High-Rise Apartment Buildings." Journal of Asian Architecture and Building Engineering 13, no. 2 (May 2014): 459–65. http://dx.doi.org/10.3130/jaabe.13.459.
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Li, Chun Chi, Chang Sheng Tai, Cheng Chyuan Lai, Shang Min Fu, and Yen Chun Tsai. "The Aerodynamic Attributes and Flight Trajectories of a Tail Fin-Stabilized Projectile." Applied Mechanics and Materials 415 (September 2013): 544–47. http://dx.doi.org/10.4028/www.scientific.net/amm.415.544.
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Combined with low-speed wind tunnel experiments, this study adopted computational fluid dynamics (CFD) and the MATLAB/Simulink control software to analyze the aerodynamic attributes of a tail fin-stabilized projectile and subsequently simulate its flight trajectory with four degrees of freedom under a flight condition (M) of 0.6 and an angle of attack (α) between-60° and 60°. Comparing the CFD calculation results with the revised experiment data using the Karman-Tsien Rule showed that the aerodynamic coefficients CD, CL, and CM were similar within an angle of attack between-30° and 30°. The projectile further demonstrated excellent aerodynamic attributes within an angle of attack between-60° and 60°, maintaining stable flight. Furthermore, comparing the four-degrees-of-freedom simulation results with data from the firing table showed that the maximum height difference of trajectories at varying angles of elevation (mil) ranged from 3.07% to 4.68%, and the difference in the firing range distance ranged from 0.15% to 5.72%. To reduce the costs of field testing, this study establishes a method to design aerodynamic systems, analyze and compare flow fields, and simulate flight trajectories.
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Kettle, Helen, Keith Beven, and Barry Hankin. "Fuzzy rules based model for solute dispersion in an open channel dead zone." Journal of Hydroinformatics 4, no. 1 (January 1, 2002): 39–51. http://dx.doi.org/10.2166/hydro.2002.0004.
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A method has been developed to estimate turbulent dispersion based on fuzzy rules that use local transverse velocity shears to predict turbulent velocity fluctuations. Turbulence measurements of flow around a rectangular dead zone in an open channel laboratory flume were conducted using an acoustic Doppler velocimeter (ADV) probe. The mean velocity and turbulence characteristics in and around the shear zone were analysed for different flows and geometries. Relationships between the mean transverse velocity shear and the turbulent velocity fluctuations are encapsulated in a simple set of fuzzy rules. The rules are included in a steady-state hybrid finite-volume advection–diffusion scheme to simulate the mixing of hot water in an open-channel dead zone. The fuzzy rules produce a fuzzy number for the magnitude of the average velocity fluctuation at each cell boundary. These are then combined within the finite-volume model using the single-value simulation method to give a fuzzy number for the temperature in each cell. The results are compared with laboratory flume data and a computational fluid dynamics (CFD) simulation from PHOENICS. The fuzzy model compares favourably with the experiment data and offers an alternative to traditional CFD models.
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Tian, Fei, Weidong Shi, and Hua Jiang. "Matching Criterion of Submersible Mixer and Pool." Advances in Mechanical Engineering 6 (January 1, 2014): 940904. http://dx.doi.org/10.1155/2014/940904.
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Matching problem of submersible mixer and pool has been a difficult problem. Based on in-depth study of the flow field characteristics of a submersible mixer, combined with fluid mechanics theory, the matching problem is discussed in this paper. Calculation formulas of the axial advance distance x and effective stirring radius R are obtained; meanwhile the critical dimension of matched pool is proposed: length × width × height = xv0.3 × 2 k1 Rv0.3 × 2 k2 Rv0.3, and calculation formula of the critical impeller diameter Dcritical is obtained. They are theoretical foundation of matching criterion between pool and submersible mixer. Matching relationship of pool and submersible mixer is widely used in engineering practice with the help of experiment and CFD numerical simulation, and it can provide significant help for the selection of a submersible mixer.
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Mao, Ning, Dongmei Pan, Mingyin Chan, and Shiming Deng. "Parameter optimization for operation of a bed-based task/ambient air conditioning (TAC) system to achieve a thermally neutral environment with minimum energy use." Indoor and Built Environment 26, no. 1 (July 28, 2016): 132–44. http://dx.doi.org/10.1177/1420326x15608678.
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The purpose of this paper is to optimize the operating parameters such as: supply air temperature, supply air flow rate and supply air humidity, for a bed-based task/ambient air conditioning (TAC) system installed in an experimental bedroom with two total insulation values of beddings and bed to obtain a thermally neutral sleeping environment with minimum energy use. A computational fluid dynamics (CFD) method was applied to calculate the values of predicted mean vote (PMV) and energy utilization coefficient (EUC) based on conditions of 16 simulation cases. From the simulation results, the design of experiment method was applied to identify operating parameters, individually or combined, that could significantly affect thermal neutrality and energy use for the bedroom environment to establish linear regression models for PMV and EUC. These models were used to obtain the optimum operating parameters of the bed-based TAC system. These models were validated by comparing the obtained optimization results using the models with the predicted results given by the CFD method. The results suggested that for a bed-based TAC system at a specified total insulation value of beddings and bed, a lower energy use can be achieved through adjusting operating parameters while the thermal comfort is maintained.
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Liu, Rui, Zhongjun Liu, Jiale Zhao, Qi Lu, Lijing Liu, and Yinghang Li. "Optimization and Experiment of a Disturbance-Assisted Seed Filling High-Speed Vacuum Seed-Metering Device Based on DEM-CFD." Agriculture 12, no. 9 (August 25, 2022): 1304. http://dx.doi.org/10.3390/agriculture12091304.
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In disturbance-assisted seed filling vacuum seed-metering devices, the suction hole causes difficulty in quickly and stably sucking seeds when used for high-speed seeding and the large working negative pressure demand is used. To address this difficulty, this study’s authors designed a seed disk hole with a variable cross-section structure, and the groove depth, which has the function of assisting seed filling, was optimized. Using the combined method of Fluent numerical analysis and an orthogonal experiment, the influence of the shape, inlet diameter, and length of the seed disk hole on the pressure difference of the seed disk hole was analyzed. The working process of the vacuum seed meter was simulated and analyzed by the Discrete Element Method and Computational Fluid Dynamics coupling method. It was found that with the increase of the diameter of the seed disk hole, the pressure difference decreased, and the length of the seed disk hole had little effect on the pressure difference. The best diameter of the seed disk hole was 5.4 mm, and the length was 5 mm. It was found that the pressurization effect of the arc-shaped seed disk hole is better. With the increase of groove depth, the leakage rate shows a trend of first decreasing and then increasing, which was determined to be 1.5 mm. The verification experiment proved that the working performance of the optimized seed metering device is better than that of the original one. The results show that when the working negative pressure was 4 kPa and the working speeds were 8~14 km·h−1, the qualified rate was not less than 95.0%, and the seed filling performance was relatively stable. The optimized vacuum seed metering device can be applied to high-speed seeders, while ensuring the requirements of high-speed sowing operations.
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Peng, Donghua, Shaohua Dong, Zhiqiang Wang, Dongying Wang, Yinuo Chen, and Laibin Zhang. "Characterization of the Solid Particle Erosion of the Sealing Surface Materials of a Ball Valve." Metals 11, no. 2 (February 4, 2021): 263. http://dx.doi.org/10.3390/met11020263.
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The ball valve is an essential piece of equipment in an oil and gas pipeline. The sand particles transported through the pipeline can cause erosion and wear to the ball valve, thus causing it to fail, leading to serious safety hazards. In this paper, the self-designed erosion experiment method was combined with computational fluid dynamics (CFD), while the Euler-Lagrange method was also introduced to optimize the Oka erosion model and Ford particle-wall rebound model. The erosion mechanism and characteristics of the ball valve sealing surface in gas-solid two-phase flow were simulated, while the erosion condition of the specimen was analyzed and compared when exposed to different factors, such as different particle velocities, impact angle, particle size, and specimen materials. The experimental data conformed well to the CFD erosion simulation data, verifying the accuracy of the CFD simulation analysis. The results indicated that the worn surface was caused by various wear mechanisms, while a “stagnation zone” was identified at the center of the specimen. The maximum erosion area, which was U-shaped, was also located at the center. The erosion rate increased in conjunction with an increase in the particle velocity and size, both of which failed to affect the erosion pattern. The erosion rate initially increased, after which it decreased with the impact angle, reaching the maximum value at an impact angle of 30°. This paper summarizes the erosion failure mechanism and characteristics in gas–solid two-phase flow and provides both technical support and a theoretical basis for the on-site maintenance of essential vulnerable parts in the pipeline, such as ball valves.
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Zhao, Xin Yi, Ke Dong Zhou, Lei He, Ye Lu, Jia Wang, and Qiu Zheng. "Numerical Simulation and Experiment on Impulse Noise in a Small Caliber Rifle with Muzzle Brake." Shock and Vibration 2019 (September 9, 2019): 1–12. http://dx.doi.org/10.1155/2019/5938034.
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Blast waves generated from the muzzles of weapons may exert negative effects, such as shock waves and impulse noise. If the weapon is fired with a muzzle brake, these effects are recognized to be more severe. This paper discusses the influence of the muzzle brake on certain aeroacoustic noise characteristics based on numerical simulations and a corresponding experiment. The impulse noise, which is induced by complex jet flows discharging from small caliber rifles with muzzle brakes, is focused in this study. Computational fluid dynamics (CFD) and computational aeroacoustics (CAA) are combined to calculate the muzzle flow field and jet noise for cases with and without a muzzle brake, and then the data sets are carefully compared. The simulations indicate that the muzzle brake alters the muzzle flow field and directional distribution of the jet noise compared to a rifle sans muzzle brake. Deviations less than 7.6% between experimental data and simulation results validate the simulation model. The results presented in this paper may provide a workable reference for the prediction of muzzle noise and the optimization of muzzle brake designs.
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Liang, Xueqi, Huiqiang Luo, Min Zeng, Yining Wu, and Qiuwang Wang. "Experimental and numerical investigation of thermal field for a motor and related factors sensitivities using combined CFD-Taguchi method." Thermal Science 23, Suppl. 4 (2019): 1065–77. http://dx.doi.org/10.2298/tsci19s4065l.
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Over-temperature is a fatal problem when a motor is running. In this work, the temperature and temperature rise of the motor are investigated experimentally and numerically. The experiment is conducted by means of both voltmeter-ammeter method and embedding thermal resistors, to obtain the mean temperature and the local temperature of the stator coils, respectively. The numerical calculation is carried out to study the temperature field of the stator and the rotor, which agrees well with the experimental result. What?s more, the sensitivity analysis of eighteen factors to the temperature is investigated using combined CFD-Taguchi method. The main conclusions are drawn. Firstly, according to the numerical results, the maximal temperature and the maximal temperature rise at rated speed are 143? and 99 K, respectively. The values are 145.8? and 90 K, according to the experimental results, which are lower than the temperature allowed, 180? and temperature rise allowed, 125 K. Secondly, the sensitivity analysis results suggest that the key factors influencing the temperature are in sequence the ambient temperature, the copper loss, the thickness of the layers, the outside convection heat transfer coefficient of crate, the iron loss at the tooth and thermal conductivity of the insulation. The contact thermal resistance and the thermal conductivity of the core in axial direction have little influence on the temperature. The rank to the temperature rise is similar except the ambient temperature, which has little effect on the temperature rise.
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Kuo, Fung-Yu, Ying-Chen Lin, Ling-Yi Ke, Chuen-Jinn Tsai, and Da-Jeng Yao. "Detection of Particulate Matter of Size 2.5 μm with a Surface-Acoustic-Wave Sensor Combined with a Cyclone Separator." Micromachines 9, no. 8 (August 12, 2018): 398. http://dx.doi.org/10.3390/mi9080398.
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A device to monitor particulate matter of size 2.5 μm (PM2.5) that has been designed and developed includes a surface-acoustic-wave sensor operating in a shear horizontal mode (SH-SAW) combined with a cyclone separator. In our tests, aerosols generated as incense smoke were first separated and sampled inside a designed cyclone separator; the sampled PM2.5 was then introduced into the sensing area of an SH-SAW sensor for detection. The use of microcentrifuge tubes as a cyclone separator effectively decreases the size and power consumption of the device; the SAW sensor in a well design and operating at 122 MHz was fabricated with MEMS techniques. After an explanation of the design of the cyclone separator, a simulation of the efficiency and the SAW sensor detection are discussed. A microcentrifuge tube (volume 0.2 mL, inlet and outlet diameters 0.5 mm) as a separator has separation cutoff diameters 50% (d50) at 2.5 μm; the required rate of volumetric flow at the inlet is 0.125 LPM, according to simulation with computational fluid dynamics (CFD) software; the surface-acoustic-wave (SAW) sensor exhibits sensitivity approximately 9 Hz/ng; an experiment for PM2.5 detection conducted with the combined device shows a strong positive linear correlation with a commercial aerosol monitor. The limit of detection (LOD) is 11 μg/m3 with sample time 160 s and total detection duration about 5 min.
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Liu, Ziyang, Chengjun Wu, and Donghong Wang. "Study on the Flow and Acoustic Field of an Electronic Expansion Valve under Refrigeration Condition with Phase Change." Shock and Vibration 2022 (May 9, 2022): 1–9. http://dx.doi.org/10.1155/2022/6714925.
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A combined numerical-experiment investigation on the flow and acoustic field of an electronic expansion valve (EEV) is conducted in this paper. In an electronic expansion valve (EEV) under refrigeration condition, it is usually complex about internal flow. There are high pressure gradient and velocity gradient in the flow field, and it also involves the process of flashing phase change, physical property change, and heat transfer, which is difficult to simulate directly. After many explorations in this paper, the flow field of EEV under refrigeration condition is simulated by a four-step computational fluid dynamics (CFD). On this basis, the noise of EEV which is induced by the internal turbulent flow and propagates outward through the shell of EEV is simulated by a Hybrid Method. Numerical simulations of the mass flow rate (MFR) and sound pressure level (SPL) are verified by experimental data. Then, the characteristics of the internal flow field causing the external acoustic radiation are analyzed and used to create an improved design that can reduce the SPL while the MFR hardly changes.
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Deng, Chao, Chunjun Chen, Qi Sun, Dongwei Wang, and Zhiying He. "Interference Elimination of Wall Fluctuation Pressure Test Signal of High-Speed Train Based on Phase Space Reconstruction and Vibration Interference Model." Fluctuation and Noise Letters 19, no. 02 (February 12, 2020): 2050020. http://dx.doi.org/10.1142/s0219477520500200.
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Because of the complexity of high-speed train operation, the measured wall pressure of high-speed train will be affected by many factors, such as train vibration and environmental changes, which make the test signal inaccurate. The main interferences are the electromagnetic interference caused by the complicated electromagnetic environment and the sensor output interference caused by the train body vibration. In this paper, ensemble empirical mode decomposition (EEMD) combined with singular value decomposition (SVD) and the local projection de-noise algorithm with better effect on non-linear time series noise reduction are used to eliminate electromagnetic interference in test signal. Because of the frequency band aliasing of test signal and interference cause by vibration, it is difficult to eliminate vibration interference by the signal processing method. In this paper, a vibration interference model is established by model-train experiment and computational fluid dynamics (CFD) software to eliminate the vibration interference in the test signal. Moreover, the theoretical guidance for accurately extracting the wall pressure of high-speed train has been put forward.
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Xiao, Senlin, Wanchen Sun, Jiakun Du, and Guoliang Li. "Application of CFD, Taguchi Method, and ANOVA Technique to Optimize Combustion and Emissions in a Light Duty Diesel Engine." Mathematical Problems in Engineering 2014 (2014): 1–9. http://dx.doi.org/10.1155/2014/502902.
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Some previous research results have shown that EGR (exhaust gas recirculation) rate, pilot fuel quantity, and main injection timing closely associated with engine emissions and fuel consumption. In order to understand the combined effect of EGR rate, pilot fuel quantity, and main injection timing on theNOx(oxides of nitrogen), soot, and ISFC (indicated specific fuel consumption), in this study, CFD (computational fluid dynamics) simulation together with the Taguchi method and the ANOVA (analysis of variance) technique was applied as an effective research tool. At first, simulation model on combustion and emissions of a light duty diesel engine at original baseline condition was developed and the model was validated by test. At last, a confirmation experiment with the best combination of factors and levels was implemented. The study results indicated that EGR is the most influencing factor onNOx. In case of soot emission and ISFC, the greatest influence parameter is main injection timing. For all objectives, pilot fuel quantity is an insignificant factor. Furthermore, the engine with optimized combination reduces by at least 70% forNOx, 20% in soot formation, and 1% for ISFC, in contrast to original baseline engine.
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Cheng, Jiarui, Yihua Dou, Ningsheng Zhang, Zhen Li, and Zhiguo Wang. "A New Method for Predicting Erosion Damage of Suddenly Contracted Pipe Impacted by Particle Cluster via CFD-DEM." Materials 11, no. 10 (September 28, 2018): 1858. http://dx.doi.org/10.3390/ma11101858.
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A numerical study on the erosion of particle clusters in an abrupt pipe was conducted by means of the combined computational fluid dynamics (CFD) and discrete element methods (DEM). Furthermore, a particle-wall extrusion model and a criterion for judging particle collision interference were developed to classify and calculate the erosion rate caused by different interparticle collision mechanisms in a cluster. Meanwhile, a full-scale pipe flow experiment was conducted to confirm the effect of a particle cluster on the erosion rate and to verify the calculated results. The reducing wall was made of super 13Cr stainless steel materials and the round ceramsite as an impact particle was 0.65 mm in diameter and 1850 kg/m3 in density. The results included an erosion depth, particle-wall contact parameters, and a velocity decay rate of colliding particles along the radial direction at the target surface. Subsequently, the effect of interparticle collision mechanisms on particle cluster erosion was discussed. The calculated results demonstrate that collision interference between particles during one cluster impact was more likely to appear on the surface with large particle impact angles. This collision process between the rebounded particles and the following particles not only consumed the kinetic energy but also changed the impact angle of the following particles.
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Wang, Chuan, Wei Dong Shi, Wei Gang Lu, Yan Xu, and Ling Zhou. "Regression Test of Stainless Steel Stamping Well-Pump Based on Numerical Simulation." Advanced Materials Research 354-355 (October 2011): 847–52. http://dx.doi.org/10.4028/www.scientific.net/amr.354-355.847.
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In order to develop stamping well pump with high efficiency, 4SP14 stainless steel stamping well pump was set as an example. Combined with the features of stamping technology, this research was taken on raising the efficiency of stamping well pump, using hydraulic design of impeller and CFD and regression test method. The experiment was designed with four factors including impeller inlet angle Δβ1, impeller outlet angle β2, and impeller outlet width b2 and inlet width of guide vane B3. 30 groups of programs were designed according to CCD central composite test method. The whole flow field of well pump at the operating point was simulated by FLUENT using the standard k-ε model, SIMPLE algorithm, first-order upwind scheme. 30 group of efficiency were obtained. Use regression equation to fit the function relationship between the efficiency value and each factor. Through the analysis of the regression equation, the optimal combination of geometric parameters can be found as inlet angle 4º, outlet angle 27.5º, outlet width 9.5mm and inlet width of guide vane 11.5mm. After manufactured and tested according to the above geometric parameters, the efficiency of the optimal model pump reaches 60.28%, which reaches the international advanced level.
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Han, Wei, Teng Zhang, You Liang Su, Ran Chen, Yan Qiang, and Yang Han. "Transient Characteristics of Water-Jet Propulsion with a Screw Mixed Pump during the Startup Process." Mathematical Problems in Engineering 2020 (May 4, 2020): 1–9. http://dx.doi.org/10.1155/2020/5691632.
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In order to investigate the transient hydrodynamic characteristics of water-jet propulsion with a screw mixed pump during the startup period and to overcome the difficulties in measuring the transient process parameters over a very short period of time, a method based on a flume experiment combined with computational fluid dynamics (CFD) is proposed. The thrust and torque of the pump-jet propulsion according to mooring status at different rotational speeds were measured by the test, which provided a group of data for the boundary and initial conditions of the numerical calculation of the user-defined function (UDF). Consecutive changes in the parameters of the water-jet propulsion dynamics can be captured from the numerical simulation of the startup process with the UDF. Thus, the transient hydrodynamic characteristics of water-jet propulsion according to time or rotation speed were obtained. The results show that the relationship between the thrust or torque of the water-jet propeller and pump rotational speed is close to the quadratic functions. The energy characteristic parameters of screw mixed water-jet pump, such as the flow rate, head, shaft power, and efficiency, rapidly increase and decrease and then remain relatively stable.
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Tang, Lingfeng, Mingwei Liu, and Feihong Ma. "Thermosetting Coupling Analysis and Parameter Optimization of the Plastic Lining Pump Structure." Advances in Materials Science and Engineering 2019 (March 11, 2019): 1–15. http://dx.doi.org/10.1155/2019/3790167.
Full textAbstract:
In order to obtain the optimum structure of the lining pump under the condition of fluid thermosetting coupling, according to the given design parameters, the structural parameters of the pump were calculated, the three-dimensional geometric model was established, and the flow field analysis was carried out by CFD; the inlet angle βb1, outlet angle βb2, wrap angle φ, inlet diameter D1, and outlet diameter D2 of the impeller were selected as the five factors to design orthogonal experiment, and the results were analyzed by range analysis; then, the efficiency and cavitation allowance were obtained as combined parameters under the evaluation index. The displacement deformation and stress distribution under the condition of the coupling field were obtained by the fluid-solid coupling analysis, and the orthogonal experimental table of the impeller structure of the lining plastic pump was established, and then the orthogonal experimental results are analyzed to obtain the influence of each structural parameter under the condition of each evaluation index and the optimum combination parameters. The influence situation and the best combination parameters under the condition of evaluation index, taking the minimum displacement deformation and minimum stress of impeller as the reference index, and the optimum combination parameters under the condition of minimum displacement and stress were as follows: the inlet diameter D1 was 76 mm, the outlet diameter D2 was 252 mm, the inlet angle was 26°, the outlet angle was 24°, and the wrap angle was 115°. Finally, the 3D printing technology was used to print out the physical model to the hydraulic performance experiment verification.
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Meister, Michael, and Wolfgang Rauch. "Modelling aerated flows with smoothed particle hydrodynamics." Journal of Hydroinformatics 17, no. 4 (March 9, 2015): 493–504. http://dx.doi.org/10.2166/hydro.2015.132.
Full textAbstract:
Modelling aerated flows is a complex application of computational fluid dynamics (CFD) since the interfaces between air and water change rapidly. In this work, the simulation of aerated flows with the smoothed particle hydrodynamics (SPH) method is investigated with a focus towards the application in engineering practice. To prove the accuracy of the method, the processes of air entrainment and rising air bubbles are studied. Through monitoring the evolution of the bubble contours it is shown that the novel approach of adding artificial repulsion forces at the interface does not alter the dynamics but stabilizes the flow. Building on these fundamental processes we extend the discussion to practical applications with a special focus on forced aeration. Since the employment of a detailed SPH model to practical problems remains out of bounds due to the high computational demand, we propose a combined experimental and numerical study where experimental bubble characteristics are imposed on the numerical simulation. Based on the data of the conducted bubble column experiment, the computational demand is significantly decreased such that the oxygen consumption due to biokinetic processes can be modelled. The future perspective is to apply SPH to urban water systems, e.g., for simulating detailed processes in wastewater treatment and sewer hydraulics.
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Zhang, Shuo, Jan Talaga, David Müller, Michal Dylag, and Günter Wozny. "Investigations of the Gas-Liquid Multiphase System Involving Macro-Instability in a Baffled Stirred Tank Reactor." Journal of Control Science and Engineering 2016 (2016): 1–10. http://dx.doi.org/10.1155/2016/3075321.
Full textAbstract:
Bubble Sauter Mean Diameter (SMD) in gas-liquid multiphase system is of particular interest and the quantification of gas characteristics is still a challenge today. In this contribution, multiphase Computational Fluid Dynamic (CFD) simulations are combined with Population Balance Model (PBM) to investigate the bubble SMD in baffled stirred tank reactor (STR). Hereby, special attention is given to the phenomenon known as the fluid macro-instability (MI), which is a large-scale low-frequency fluid velocity variation in baffled STRs, since the fluid MIs have a dominating influence on the bubble breakage and coalescence processes. The simulations, regarding the fluid velocity, are validated with Laser Doppler Anemometry (LDA) experiments, in which the instant radial velocity is analyzed through Fast Fourier Transform (FFT) spectrum. The frequency peaks of the fluid MIs are found both in the simulation and in the experiment with a high degree of accuracy. After the validation, quantitative predictions of overall bubble SMD with and without MIs are carried out. Due to the accurate prediction of the fluid field, the influence of the fluid MI to bubble SMD is presented. This result provides more adequate information for engineers working in the field of estimating bubble SMDs in baffled STRs.
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Zhu, D. X., Y. Yang, Z. J. Yu, Z. P. Li, and L. K. Dong. "Optimization of the aerodynamic characteristics of a NACA air intake based on DoE and numerical methods." Journal of Physics: Conference Series 2029, no. 1 (September 1, 2021): 012101. http://dx.doi.org/10.1088/1742-6596/2029/1/012101.
Full textAbstract:
Abstract The Design of Experiment (DoE) method combined with numerical simulations is employed to optimize the aerodynamic characteristics of a National Advisory Committee for Aeronautics (NACA) air intake. The drag force, total pressure recovery coefficient, mass flow rate at the outlet, and Mach number at the outlet are used to evaluate the performance of the air intake based on computational fluid dynamics (CFD) numerical methods. Three critical geometric parameters, namely the ramp angle a, ramp divergence angle θ, and turning corner radius R, are considered as variables in the DoE design. Results under the baseline conditions indicated that axial vortexes are formed near the side edge close to the ramp wall. DoE analysis indicated that above four performance parameters are largely influenced by the ramp angle a, while the ramp divergence angle θ has negligible effects. A small radius of the turning corner is beneficial to enhance the pressure recovery coefficient and the mass flow rate. The Mach number at the outlet declines and the velocity uniformity on a certain section increases with decreasing value of ramp angle a. Meanwhile, larger total pressure recovery coefficient, mass flow rate, and vortex tube length are acquired under a smaller value of a. Thus, the aerodynamic performance of this air intake can be improved by a set of optimized geometric parameters.
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Wang, Dong, Zhenggui Li, Qing Zhao, Deyou Li, Wanquan Deng, Lei Ji, and Peng Shengyang. "Pressure pulsation analysis of runner and draft tube of pump turbine under different working conditions." IOP Conference Series: Earth and Environmental Science 1037, no. 1 (June 1, 2022): 012036. http://dx.doi.org/10.1088/1755-1315/1037/1/012036.
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Abstract As the core component of pumped storage power station, the pump turbine usually needs to adjust the operating condition point according to the electricity demand during operation. Pressure pulsation is an inevitable phenomenon in the operation of pump turbine, which affects the safe and stable operation of the unit. In this paper, the method of combining numerical simulation and experiment is adopted to carry out three-dimensional full flow channel numerical simulation of the pump turbine by using CFD. The flow pattern and pressure pulsation of the runner and draft tube of the pump turbine were analyzed at the three working conditions of PL (50% maximum load), BEP (70% maximum load) and HL (90% maximum load). It is found that under the three conditions, the pressure pulsation from the leafless area to the downstream of the draft tube shows a weakening trend. Because the flow pattern in the bladed area of the unit is poor, the pressure pulsation in the bladed area is the most obvious. From low load to high load, the pressure pulsation tends to weaken at first and then increase. Combined with flow pattern analysis and vortex analysis, it can be concluded that the number and scale of vortex flow are positively correlated with the pressure pulsation, and the vortex flow inside the unit is an important factor that causes the flow disorder inside the unit, and then becomes an important factor that affects the pressure pulsation inside the pump turbine unit.
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Zhao, Yuanyuan, Xiuli Wang, and Rongsheng Zhu. "Effect of eccentricity on radial force and cavitation characteristics in the reactor coolant pump." Thermal Science, no. 00 (2020): 312. http://dx.doi.org/10.2298/tsci200608312z.
Full textAbstract:
Nuclear reactor coolant pump as one of the most critical equipment is the only one rotating equipment in first loop system of nuclear power plant. Due to the asymmetric structure of the pump body, especially the existence of outlet segment lead to a certain of radial force, the magnitude of radial force directly affects the work stability of the reactor coolant pump. The nuclear reactor coolant pump could stability work under those transient complex conditions is an important index of its performance. To study the cavitation characteristics and radial force of reactor coolant pump on transient cavitation, a prototype pump and those exhibiting different gravity center offsets are analyzed numerically with CFD software ANSYS CFX by employing RNG k-? model and two-fluid two-phase flow model. Through the experiment-combined simulation, the variations of cavitation characteristics and radial force of the reactor coolant pump under different eccentricities are characterized. As revealed from the results, the flow characteristics of the internal flow field of the nuclear main pump change after the axis is offset by different distance. The influence of eccentricity on the cavitation of the nuclear main pump is mainly manifested at the impeller inlet from cavitation inception to severe cavitation. When the eccentricity is 5mm, the cavitation performance is improved. The effect of eccentricity on the radial force of impeller is reflected in the variation of force direction. Compared with other plans, the radial force is superior in transient cavitation under the eccentricity of 5mm.
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Wang, Zhihong, Chunguang Wang, and Weiping Tian. "Study on Separation Characteristics of Nozzles with Large Expansion Ratio of Solid Rocket Motors." Aerospace 10, no. 1 (December 21, 2022): 4. http://dx.doi.org/10.3390/aerospace10010004.
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In order to study the flow characteristics of a nozzle with large expansion ratio and its influence on the force on the nozzle, ground cold flow test research and a fluid–structure coupling simulation analysis were carried out (maximum expansion ratio ε = 30.25). The variation and pulsation characteristics of the pressure near the measuring point area and the inlet pressure were obtained through experiments. Through the analysis of the peak-to-peak value and average value, it was found that the average pressure after separation increases by 90%, but the peak-to-peak value increases by about five times, indicating that the pressure fluctuation after separation is much larger than before separation. The separation flow field under cold flow conditions was simulated using the CFD commercial calculation software Fluent to verify the correctness of the numerical calculations. The fluid–structure coupling analysis was carried out on a large expansion ratio (maximum expansion ratio ε = 48) full-scale nozzle, and the structural deformation characteristics of the nozzle under the separation conditions were studied. The research results show that flow separation occurs in the nozzle with a large expansion ratio under ground conditions. Before the separation point, the pressure pulsation on the nozzle wall is small, and the turbulent pulsation effect is weak. After the separation point, the pressure pulsation increases, and the turbulent pulsation effect is enhanced. When the total pressure decreases, the separation area of the nozzle increases, and the separation flow field presents a strong asymmetry. Reducing the total inlet pressure by half resulted in approximately 50 times the lateral load. Under the combined influence of the ground conditions and low total pressure, the large lateral load caused by the asymmetry of the separation flow field will cause the deformation of the nozzle structure to increase by 5.5 times. This research provides an important reference for the design and experiment of nozzles with a large expansion ratio.
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Li, Yao Ming, and Fang Li. "Numerical Simulation on Air Flow Field of Tangential Longitudinal Axial Combine Harvester." Advanced Materials Research 971-973 (June 2014): 605–8. http://dx.doi.org/10.4028/www.scientific.net/amr.971-973.605.
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Withthe use and popularization of the tangential longitudinal axial combineharvester,the cleaning device of high loss rate and impurity rate continuouslyemerging.In order to analyses the reason of cleaning performance is low,thestudy for airflow field distribution of thetangential-longitudinal axial combine harvester has been carried out.Based onhomogenization when Reynold continuous equation and navier-stokes equation andthe renormalization group (RNG) kappa epsilon turbulence model predominateconstitute a closed equations,Using CFD simulation software simulated thecleaning shoe airway airflow.The simulation results show that the cleaning shoeair distribution is symmetrical in the screen surface width direction.Along thescreen surface height direction airflow velocity decreases gradually,Along thescreen length direction ,at the front of the sieve air velocity is low,Near themiddle of the screen as to achieve the maximum of air velocity.And for cleaningshoe air flow field were measured experiment, verify the accuracy of flow fieldsimulation.
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Ding, Bochuan, Zhenwei Liang, Yongqi Qi, Zhikang Ye, and Jiahao Zhou. "Improving Cleaning Performance of Rice Combine Harvesters by DEM–CFD Coupling Technology." Agriculture 12, no. 9 (September 13, 2022): 1457. http://dx.doi.org/10.3390/agriculture12091457.
Full textAbstract:
The cleaning device is an important part of combine harvesters, as its superior or inferior performance directly affects the performance of the combine harvester greatly. With an increasing rice yield, the current single-duct cleaning performance declines greatly, and causes a large grain sieve loss level and a direct grain loss for the farms. To optimize the existing single-duct cleaning device to meet the large feeding rate requirement, firstly, the terminal velocity of rice grain and MOG (material other than grain) for different varieties was experimentally measured by the custom-made device. The effects of the moisture content of rice grains and the length of short straws on terminal velocity were studied in detail. Then, the gas–solid two-phase flow theory was comprehensively applied by utilizing the discrete element method (DEM) and computational fluid dynamics (CFD) to study the working mechanism of the existing single-duct cleaning unit, and the cleaning performance was evaluated from the view of the motion law of the threshing output within the cleaning shoe. At last, a multi-duct cleaning device was put forward, and a field experiment was performed to assess the performance of the newly developed cleaning device. The results showed that the grain sieve losses ratio and grain impurity ratio improved dramatically, proving that structure optimization of the cleaning device was feasible.
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Firdaus, Rachmat, Takahiro Kiwata, Koji Nagao, and Takaaki Kono. "The influence of the number of rotor blades on the performance of orthopter wind turbine." MATEC Web of Conferences 197 (2018): 08008. http://dx.doi.org/10.1051/matecconf/201819708008.
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This paper describes the influence of the number of rotor blades the performance of the orthopter wind turbine. The orthopter wind turbine is combination between a drag-type and a lift-type vertical axis wind turbine which each blade combines a rotating movement around its own axis and a rotating movement around turbine's axis. In this case, the pitch of the blades was controlled by using a chain and sprockets arrangement to ensure that the blades rotated around their own axis by 360 degrees during the each two full revolution of the main rotor. To improve the performance of this wind turbine, the number of blades, was investigated by wind tunnel. By conducting two-dimensional unsteady CFD simulations, the power and torque of the vertical axis wind turbine and the flow around blades were also analyzed. The numerical simulation by using turbulence model predicted good agreement of the performance with experiment qualitatively.
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Zhou, Shudao, Shuling Peng, Min Wang, Ao Shen, and Zhanhua Liu. "The Characteristics and Contributing Factors of Air Pollution in Nanjing: A Case Study Based on an Unmanned Aerial Vehicle Experiment and Multiple Datasets." Atmosphere 9, no. 9 (September 2, 2018): 343. http://dx.doi.org/10.3390/atmos9090343.
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Unmanned aerial vehicle (UAV) experiments, multiple datasets from ground-based stations and satellite remote sensing platforms, and backward trajectory models were combined to investigate the characteristics and influential mechanisms of the air pollution episode that occurred in Nanjing during 3–4 December 2017. Before the experiments, the position of the detector mounted on a UAV that was minimally disturbed by the rotation of the rotors was analyzed based on computational fluid dynamics (CFD) simulations. The combined analysis indicated that the surface meteorological conditions—high relative humidity, low wind speed, and low temperature—were conducive to the accumulation of PM2.5. Strongly intense temperature inversion layers and the low thickness of the atmospheric mixed layer could have resulted in elevated PM2.5 mass concentrations. In the early stage, air pollution was affected by the synoptic circulation of the homogenous pressure field and low wind speeds, and the pollutants mainly originated from emissions from surrounding areas. The aggravated pollution was mainly attributed to the cold front and strong northwesterly winds above 850 hPa, and the pollutants mostly originated from the long-distance transport of emissions with northwesterly winds, mainly from the Beijing‒Tianjin‒Hebei (BTH) region and its surrounding areas. This long-distance transport predominated during this event. The air pollution level and aerosol optical depth (AOD) were positively correlated with respect to their spatial distributions; they could reflect shifts in areas of serious pollution. Pollution was concentrated in Anhui Province when it was alleviated in Nanjing. Polluted dust, polluted continental and smoke aerosols were primarily observed during this process. In particular, polluted dust aerosols accounted for a major part of the transport stage, and existed between the surface and 4 km. Moreover, the average extinction coefficient at lower altitudes (<1 km) was higher for aerosol deposition.
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Li, Yiqun, Wenhao Tang, Chao Wu, Yu Xue, Wei Ye, and Xu Zhang. "The feasibility of jet fan-assisted ventilation for temperature control of heating belts on a downward-facing sphere in a scientific facility." E3S Web of Conferences 356 (2022): 02005. http://dx.doi.org/10.1051/e3sconf/202235602005.
Full textAbstract:
To avoid the deformation of the large-scale scientific facility for neutrinos detection due to temperature changes, the heat generated during the top-down annealing of the inorganic glass panels needs to be released in time to maintain temperature control of 21±1°C in the built-up area. Due to the unique shape and the changing heating sources, a novel ventilation strategy that combines jet fans with general ventilation was proposed to satisfy the special environmental control requirement. A small-scale field experiment was conducted to obtain the CFD methods for simulation. Then, the feasibility of the jet fan-assisted ventilation system was discussed in terms of two thermal control zones based on the distance from the heat source. Besides, the effectiveness of the proposed ventilation design was compared with traditional general ventilation with air-conditioned air supplied from the hall ceiling and directly opposite the heating belt based on the temperature and velocity distribution. The results show that: the area outside the thermal control range under jet fan-induced ventilation was reduced by around 60%, and the maximum temperature fluctuated over time within 0.33°C. These results provide a preliminary insight into the use of jet fan-assisted ductless ventilation to achieve precision local temperature control in a large space.
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Wang, Chuanzhen, Anghong Yu, Zaisheng Zhu, Haizeng Liu, and Md Shakhaoath Khan. "Mechanism of the Absent Air Column in Three Products Hydrocyclone Screen (TPHS): Experiment and Simulation." Processes 9, no. 3 (February 27, 2021): 431. http://dx.doi.org/10.3390/pr9030431.
Full textAbstract:
Three products hyrdrocyclone screen (TPHS) has been proposed for particle separation based on size. In TPHS, a cylindrical screen was embedded in a conventional hydrocyclone (CH) to combine the centrifugal classification and screening to particle separation based on size. The industrial application of TPHS indicates its better device performance than CH. Although, the earlier studies reveal some common understanding for TPHS, the information of the absent air column remains unknown. Hence, the combination of physical experiment and numerical simulation was considered involving a 75 mm TPHS for this knowledge gap. First, both the computational fluid dynamics (CFD) simulation with Reynolds stress mode and the physical experiment with a high-definition camera illustrate the development process details of a flow field in TPHS. That is, the water was imported along the tangential inlet into TPHS; then under the effects of the feed chamber wall and gravity, the liquid phase spiraled downward until the cylindrical screen passed through the sieve; as the liquid moved to the spigot, it could be discharged in time due to the small underflow port, thus the volume fraction of air rapidly reduced from 1 to 0; subsequently the water filled the TPHS and the absent air column could be observed. Furthermore, the distribution comparisons of air volume fraction and static pressure show that TPHS displayed the absent air core with the negative static pressure in the center region along the z-axis, while CH displayed the opposite features. In addition, despite the different inlet velocity, TPHS consistently presented the vanished air column which could be ascribed to the fact that the present cylindrical screen resulted in positive static pressure distribution inside TPHS.
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Xu, Taibai, and Yaoming Li. "Effect of Airflow Field in the Tangential-Longitudinal Flow Threshing and Cleaning System on Harvesting Performance." Advances in Materials Science and Engineering 2020 (August 5, 2020): 1–11. http://dx.doi.org/10.1155/2020/4121595.
Full textAbstract:
The threshing and cleaning device in the grain combine harvester is located in the same airtight space, and the air flow field in it should also be studied and tested as a whole system. In order to study the distribution of air flow field and the influence of working parameters on the air flow field in the internal space of threshing and cleaning system, the method of predicting harvest performance indexes (grain loss rate and grain impurity rate) by air flow field analysis was explored. First of all, taking the longitudinal grain combine harvester of our research group as the test object and taking the rotating speed of centrifugal fan, the angle of fan plate, the opening of chaffer, and the rotating speed of threshing cylinder as the research factors, the internal space flow channel model of threshing and cleaning system under different working conditions was established and CFD software was used to simulate and analyze the air flow field. At the same time, the hot wire anemometer is used to measure and verify the distribution of air flow field in the threshing and cleaning system under various working conditions. Then, the harvest performance index of the threshing and cleaning system under the rated feeding rate is tested under the corresponding working conditions to find the relationship between the distribution of air flow field and harvest performance, put forward the corresponding analysis and prediction methods, and establish the mathematical relationship model between the simulated air flow field and harvest performance index. The results of simulation and experiment show that the average air velocity can more accurately reflect the cleaning performance. The mathematical function of the relation curve is Y = 11.71X − 4.76, and the prediction error is within 9.4%. The air velocity in the middle area of the vibrating screen is approximately in proportion to the cleaning performance, which provides the theoretical and experimental basis for the design of the threshing and cleaning device and the adjustment of the working parameters in the field harvest. In addition, it can save the design time and cost and reduce the seasonal impact of field experiment.
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Wen, Jiayu, Yanguo Song, Huanjin Wang, and Dong Han. "Numerical Study on Tandem-Rotor Autorotation in Forward Flight." Aerospace 10, no. 1 (December 24, 2022): 15. http://dx.doi.org/10.3390/aerospace10010015.
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This work presents a systematic approach to analyzing the aerodynamic characteristics of tandem rotor forward autorotation considering rotor-to-rotor interference. The single-rotor computational model trimmed from a generic helicopter flight dynamics analysis program was used as the baseline model. The effectiveness of the baseline model is demonstrated by a comparison with data from wind tunnel tests performed in this work. The rotor disk angle of attack and driven moment distribution obtained by the modified model indicate the fact that the rotor acceleration is primarily caused by the higher angle of attack region of the disk. This is of great significance in the rotor blade design, in terms of the drag-to-lift ratio characteristics of the airfoil under different angle-of-attack ranges. The influence of wind speed, rotor shaft angle, and collective pitch on the steady-state rotor speed was then studied. The results show a nonlinear nature of the variation of steady rotor speed with collective pitch, which can cause a thrust control reverse problem during flight operations. To reveal the flow field details of rotor-to-rotor interference, the flow field Navier–Stokes equations of tandem rotor autorotation were solved. Computational results of both rotors’ inflow velocities were considered when deriving the empirical model of interference. The refined interference model was compared to the wind tunnel test data of the tandem rotor autorotation and showed good performance. This synthetical methodology, which combines mechanism analysis with CFD-aided refinement and experiment verification, achieves a balance between computational costs and accuracy and thus can be readily applied to engineering practices.
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Na, Xinchen, Yingxue Yao, Chenyang Zhao, and Jianjun Du. "Heat Loss Reduction Approach in Cavity Receiver Design Based on Performance Investigation of a Novel Positive Conical Scheme." Energies 15, no. 3 (January 21, 2022): 784. http://dx.doi.org/10.3390/en15030784.
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The cavity receiver’s thermal conversion performance is critical for parabolic dish and tower Concentrated Solar Power (CSP) systems. Distinct from precedent research aiming to increase the receiver’s absorption through cavity geometry optimization, the objective of this work was to investigate the thermal conversion performance of a novel, positive conical cavity receiver design, following the heat loss reduction approach with simplified pipe forming, to stress the effectiveness of this approach in cavity receiver design, and to provide data for future optimization of the proposed design. To accomplish these goals, the novel receiver and existing designs’ heat flux absorption and heat loss are compared numerically. The resulting conversion power is also experimentally validated. The concept is inspired by analysis of formulas, suggesting the novel design may realize a thermal conversion improvement of 8.6%, at 650 K, and increases with the rise in temperature. The comprehensive numerical investigation combines ray tracing of identical incoming radiation to investigate the receiver absorption and CFD methods to investigate the cavities’ heat loss at identical temperatures. The absorption acquired is unoptimized. The novel design can reduce the heat loss by as much as 91.8% when compared with a negative conical design at 650 K, resulting in a 12.3% improvement in conversion power. The experimental investigation measures the energy conversion to the working fluid in different cavities under identical incoming radiation. The novel receiver outperforms by over 5.6% in the setup. After correcting boundary conditions using experiment measurements, the experimental and numerical results are comparable. This research proves that the novel positive conical receiver has a better thermal conversion performance over 650 K; thus, the heat loss reduction approach is effective and feasible in receiver designs within this temperature range.
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Rahimi, Mahmood Reza. "A Combined Computational Fluid Dynamics and Artificial Neural Networks Model for Distillation Point Efficiency." Chemical Product and Process Modeling 7, no. 1 (May 17, 2012). http://dx.doi.org/10.1515/1934-2659.1636.
Full textAbstract:
In this work a CFD-ANN model is developed to give the predictions of sieve tray point efficiency. The main objective has been to find the extent to which CFD can be used in combination with artificial neural network as a prediction tool for efficiencies of industrial trays. The model was tested against a wide range of tray geometries, operating conditions and binary systems of materials. CFD model was applied, as a virtual experiment tool for direct prediction of point efficiencies, using tray geometries and operating conditions for any binary system of liquids. The model results were in agreement to experimental data from literatures, shown that CFD-ANN model can be used as a powerful tool in distillation column design and analysis.
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Baek, Seoung-Ho, Jung-Ho Yang, Cheol-Woo Ha, Patrick Y. Shim, Son Yong, and Sang-Hu Park. "Design and evaluation of additive manufactured highly efficient inclined-wing type continuous mixer." Scientific Reports 12, no. 1 (November 14, 2022). http://dx.doi.org/10.1038/s41598-022-23809-2.
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AbstractWe develop a novel milli-scale mixer (tilted-wings mixing unit, TWM unit) based on the design for additive manufacturing (DfAM). The proposed tilted-wings mixer has basically designed to have three separate wings that split and combine fluids in order to mix together effectively. Its structure is simple for easy fabrication: two major design parameters of angle among three wings and connecting angle between tilted-unit, which are optimized using the computational fluid dynamics (CFD) analysis. From the CFD analysis, we obtain the best-combined mixing module from analyses of various combinations of TWM units for a highly effective mixing ratio. The mixing ratio of three combined units reaches near 100%, which is validated by the experiment and analysis. We believe that the proposed milli-scale mixer can be utilized in diverse chemical continuous mixers and reactors for minimizing of use of chemicals that can pollute the environment.
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Zhu, Zanbin, Yubin Li, and Shoufu Gong. "Design and experiment of IOT cooling system in glass greenhouse based on CFD simulation." Journal of Agricultural Engineering, July 25, 2022. http://dx.doi.org/10.4081/jae.2022.1384.
Full textAbstract:
In the summer heat season, the performance of greenhouse cooling system is the key factor of the greenhouse crop pollination and fruit formation. Scientific design of greenhouse cooling system and intelligent control of cooling equipment can ensure the normal growth of greenhouse crops and save energy. In this paper, the thermal equilibrium theory of greenhouse is analyzed, and the thermal environment model of glass greenhouse is established based on the theory of engineering thermophysics combined with greenhouse environmental regulation. This study uses CFD (Computational Fluid Dynamics) simulation technology to simulate the change of greenhouse temperature field and perform experimental analysis, and designs an intelligent greenhouse temperature control cooling system scientifically. It provides reference for the design of IOT (Internet of Things) cooling system in glass greenhouse in theoretical analysis and engineering practice.
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Zhu, Zanbin, Yubin Li, and Shoufu Gong. "Design and experiment of IOT cooling system in glass greenhouse based on CFD simulation." Journal of Agricultural Engineering, July 25, 2022. http://dx.doi.org/10.4081/jae.2022.1384.
Full textAbstract:
In the summer heat season, the performance of greenhouse cooling system is the key factor of the greenhouse crop pollination and fruit formation. Scientific design of greenhouse cooling system and intelligent control of cooling equipment can ensure the normal growth of greenhouse crops and save energy. In this paper, the thermal equilibrium theory of greenhouse is analyzed, and the thermal environment model of glass greenhouse is established based on the theory of engineering thermophysics combined with greenhouse environmental regulation. This study uses CFD (Computational Fluid Dynamics) simulation technology to simulate the change of greenhouse temperature field and perform experimental analysis, and designs an intelligent greenhouse temperature control cooling system scientifically. It provides reference for the design of IOT (Internet of Things) cooling system in glass greenhouse in theoretical analysis and engineering practice.
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Lu, Chunxi, Nana Qi, Kai Zhang, Jiaqi Jin, and Hu Zhang. "Experiment and CFD Simulation on Gas Holdup Characteristics in an Internal Loop Reactor with External Liquid Circulation." International Journal of Chemical Reactor Engineering 7, no. 1 (January 26, 2009). http://dx.doi.org/10.2202/1542-6580.1518.
Full textAbstract:
An external liquid circulation is introduced into a traditional internal loop reactor in order to improve liquid circulation and increase the interface between gas and liquid phases. The effects of superficial gas velocity and external liquid circulation velocity on local and overall gas holdups are explored experimentally and numerically in the loop section of a combined gas-liquid contactor, which consists of a liquid spray, sieve plates and an internal loop with external liquid circulation. Local gas holdup is measured experimentally by a double-sensor conductivity probe. Numerical simulations are conducted in the platform of a commercial software package, ANSYS CFX 10.0. Gas holdup and other information are obtained by solving the governing equations of mass and momentum balances for gas and liquid phases in a hybrid mesh system. Both measured and simulated results indicate that local, section-averaged, and overall gas holdups increase with an increase of the superficial gas velocity. The downcomer tube for circulating external liquid has a significant influence in the gas-distributor and the downcomer-tube action regions rather than in the upper draft-tube and the gas-liquid separation regions. Good agreement between measured and predicted data suggests that CFD simulation together with experimental investigation can be employed to develop novel gas-liquid contactors with a complex geometrical configuration.
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Zhang, Kaixing, Lan Zhang, Yang Ding, Xianxi Liu, and Xiuyan Zhao. "DESIGN AND TEST OF AIR-SUCTION PEPPER SEED METERING DEVICE BASED ON AIR SUPPLY AND QUANTITATIVE SEED SUPPLY." INMATEH Agricultural Engineering, August 31, 2021, 345–54. http://dx.doi.org/10.35633/inmateh-64-34.
Full textAbstract:
In order to solve the problem that the current precision seeder has difficulty in precision sowing pepper seeds, an air-suction pepper seed metering device based on air supply and quantitative seed supply was developed. Combined with its basic structure and working principle, the CFD-DEM coupling method was used for analysis, and the best combined hole parameters were obtained. A single factor experiment with the pass rate, replay rate, and missed rate as experimental indicators was designed. Regression model was established to obtain a reasonable range of each parameter. The results showed that when the speed of the drum barrel was 28.65r/min and the working negative pressure was 4.40kPa, the seeding pass rate of the seed meter was 91.32%, the replay rate was 4.51%, and the missed rate was 4.17%. The comprehensive performance index was better.
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Fei, Sun, Ji Hong, Peng Yanbo, and Li Chen. "Numerical simulation and prototype experiment of integrated electrohydraulic pump." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, April 16, 2022, 095440622210769. http://dx.doi.org/10.1177/09544062221076982.
Full textAbstract:
Integrated electrohydraulic pump (IEHP) is conceived as an innovative design concept to achieve the higher power density, lower noise level, and leakage-free with respect to the traditional hydraulic power units. Nevertheless, the complex cooling circuit may increase the flow resistance, reducing the effective delivery flow rate of IEHP, which will be more serious at high rotational speed. In this context, a novel centrifugal charging pump (CCP) integrated on the hollow drive shaft is arranged on the suction path of positive-displacement vane pump (main pump) to boost its inlet pressure, thus efficiently improving the suction capability of IEHP. The contribution of this study is to develop a full flow field CFD model of IEHP, in which the fluid domain of main pump and CCP are connected in series. Based on the CFD model validated subsequently by prototype experiment in terms of volumetric efficiency, the charging effect of CCP modeled with different geometric parameters, at 1,500 r/min, has been investigated. Finally, combined with experiment and simulation, the delivery flow rate of IEHP, in the speed range 600–6,000 r/min, are also analyzed by means of comparing with a standard vane pump. The results show that the CCP makes an outstanding contribution to the filling of main pump, especially when the rotational speed exceeds 3,000 r/min; Since then, the flow rate saturation of standard vane pump tends to occur due to serious incomplete filling, while the IEHP still maintains valid output. It can be concluded that, with the help of charging effect of CCP, the IEHP can keep the same volume efficiency as the vane pump under rated speed, and there is a certain potential for the application of IEHP in a wide speed range.
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Evan Bush, H., Karl-Philipp Schlichting, Robert J. Gill, Sheldon M. Jeter, and Peter G. Loutzenhiser. "Design and Characterization of a Novel Upward Flow Reactor for the Study of High-Temperature Thermal Reduction for Solar-Driven Processes." Journal of Solar Energy Engineering 139, no. 5 (July 18, 2017). http://dx.doi.org/10.1115/1.4037191.
Full textAbstract:
The design and characterization of an upward flow reactor (UFR) coupled to a high flux solar simulator (HFSS) under vacuum is presented. The UFR was designed to rapidly heat solid samples with concentrated irradiation to temperatures greater than 1000 °C at heating rates in excess of 50 K/s. Such conditions are ideal for examining high-temperature thermal reduction kinetics of reduction/oxidation-active materials by temporally monitoring O2 evolution. A steady-state, computational fluid dynamics (CFD) model was employed in the design to minimize the formation of eddies and recirculation, and lag and dispersion were characterized through a suite of O2 tracer experiments using deconvolution and the continuously stirred tank reactors (CSTR) in series models. A transient, CFD and heat transfer model of the UFR was combined with Monte Carlo ray tracing (MCRT) to determine radiative heat fluxes on the sample from the HFSS to model spatial and temporal sample temperatures. The modeled temperatures were compared with those measured within the sample during an experiment in which Co3O4 was thermally reduced to CoO and O2. The measured temperatures within the bed were bounded by the average top and bottom modeled bed temperatures for the duration of the experiment. Small variances in the shape of the modeled versus experimental temperatures were due to contact resistance between the thermocouple and particles in the bed and changes in the spectral absorptivity and emissivity as the Co3O4 was reduced to CoO and O2.
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Zhang, Guolong, Qingwen Zhang, Huamei Mo, Rui Li, Mengmeng Liu, and Feng Fan. "Experimental Investigation of Snow Accumulations on Two-Span Single-Pitched Roofs Based on a New Similarity Criterion." Frontiers in Earth Science 10 (May 11, 2022). http://dx.doi.org/10.3389/feart.2022.785010.
Full textAbstract:
Uneven snow distribution plays a main role in the collapse of two-span single-pitched roofs because of the intensified snow accumulation in the valleys and eaves. The roof pitches, wind velocities, and wind directions are the main reasons that cause unbalanced snowdrifts as they drastically affect the flow fields around the roofs. This research investigates the snow distribution characteristics on two-span single-pitched roofs based on the snow-wind combined experiment facility and new similarity criteria. Firstly, the setup of the experiment facility is introduced, and the wind fans matrix and snowfall simulator are calibrated, respectively. Then, a new Froude number similarity, based on the modification of friction velocity ratio, is proposed, and its reliability as a criterion is verified. Finally, experiments on two-span single-pitched roofs are conducted using the new similarity criteria to study the snowdrifts patterns under different conditions. The mechanism of snow accumulations on roofs is explained with the help of CFD calculation. The results show that the valley and eave on the second windward roof bear a larger snow load.