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1
Yang, Qinghua, und Qian Yang. „Numerical investigation of the turbulence characteristics and energy dissipation mechanism of baffle drop shafts“. Water Science and Technology 83, Nr. 9 (07.04.2021): 2259–70. http://dx.doi.org/10.2166/wst.2021.137.
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Abstract The baffle drop shaft is widely used in deep tunnel drainage systems due to its fine applicability and high energy dissipation. To fully study the turbulence characteristics and energy dissipation mechanism of baffle drop shafts, a 1:25 scale physical model test and a numerical simulation based on the Realizable k-ε model and Volume of Fluid (VOF) method were performed. The results showed that a baffle spacing that is too dense or too sparse is not conducive to energy dissipation and discharge. The minimum baffle spacing is the optimal structural design at the design flow rate when the flow regime is free-drop flow. The energy dissipation calculation model established in this paper has high accuracy for calculating the energy dissipation rate on the baffles in free-drop flow. The energy dissipation modes of the shaft can be divided into inlet energy dissipation, baffle energy dissipation, and shaft-bottom energy dissipation. Baffles play a major role in the energy dissipation at low flow rates, and the proportions of inlet and shaft-bottom energy dissipation increase with the increase in flow rate.
2
Sun, Jianchun, Heng Zhang, Muyan Huang, Qianyang Chen und Shougen Chen. „Reasonable Paths of Construction Ventilation for Large-Scale Underground Cavern Groups in Winter and Summer“. Sustainability 10, Nr. 10 (18.10.2018): 3768. http://dx.doi.org/10.3390/su10103768.
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Forced ventilation or newly built vertical shafts are mainly used to solve ventilation problems in large underground cavern groups. However, it is impossible to increase air supply due to the size restriction of the construction roadway, resulting in ventilation deterioration. Based on construction of the Jinzhou underground oil storage project, we proposed both a summer ventilation scheme and winter ventilation scheme, after upper layer excavation of the cavern is completed and connected with the shaft. A three-dimensional numerical model validated with field test data was performed to investigate air velocity and CO concentration. Fan position optimization and the influence of temperature difference on natural ventilation were discussed. The results show that CO concentration in the working area of the cavern can basically drop to a safe value of 30 mg/m3 in air inlet and exhaust schemes after 10 min of ventilation. Since there is inevitably a back-flow in the winter ventilation scheme, it is necessary to ensure that airflow is always moving towards the shaft. Optimal placement of the axial flow fan at the shaft bottom is on the central axis of the cavern, 5 m away from the shaft. The greater the temperature difference, the better the natural ventilation effect of the shaft. The natural ventilation effect of the shaft as an outlet in winter, is better than that of the shaft as an inlet in summer.
3
Fernandes, João, und Ricardo Jónatas. „Experimental flow characterization in a spiral vortex drop shaft“. Water Science and Technology 80, Nr. 2 (15.07.2019): 274–81. http://dx.doi.org/10.2166/wst.2019.274.
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Abstract Connecting storm-sewers located at rather different elevations may be made with vortex drop shafts in which the energy dissipation is made by the friction between the vertical shaft and the flow and downstream by the impinging jet in a dissipation chamber. Following the first model design in the 1940s, different types of vortex drop shafts have been developed. One of the most used type is the so-called spiral vortex drop shaft developed to work in supercritical flow with good performance in both energy dissipation and space constrains. In this paper, an experimental flow characterization in a spiral vortex drop shaft is conducted covering the three main components of these structures, namely the inlet channel, the vertical shaft and the dissipation chamber. The results include measurement of water depths, pressure and velocity.
4
Alpan, K., und W. W. Peng. „Suction Reverse Flow in an Axial-Flow Pump“. Journal of Fluids Engineering 113, Nr. 1 (01.03.1991): 90–97. http://dx.doi.org/10.1115/1.2926503.
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Experiments are carried out to determine the effects of different inlet geometries on the onset of suction recirculation and its associated power consumption in an axial-flow pump. The critical flow rate is determined by both the “string” visual technique and “pressure” method. The results are correlated with the inlet area and flow velocity distribution upstream of the impeller. Four different conical covers matching the impeller leading edge are employed to cover the impeller inlet completely or partially. Covering the inlet area reduces the critical flowrate corresponding to the onset of suction recirculation and eliminates all recirculation at higher flowrates. The power consumption associated with the suction recirculation flow for the uncovered impeller is determined by comparing the shaft powers with and without inlet covers. At the shut-off condition, the power is estimated from a comparison with the shaft power measured with the impeller inlet completely covered. Experimental studies conclude that the power consumption due to suction recirculation is mainly controlled by the impeller inlet area and is insensitive to the inlet pipe configuration. At shut-off condition, the power coefficient correlates well with the parameter based on the hydraulic radius of inlet area. At a finite through flowrate the analytical model recommended by Tuzson (1983) is adequate, except for a proportionality coefficient determined from the test data.
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Yao, Zhishu, Ping Zhang, Hua Cheng, Weipei Xue und Xiang Li. „Testing of a Dual-Steel-Plate-Confined High-Performance Concrete Composite Shaft Lining Structure and Its Application“. Applied Sciences 10, Nr. 8 (23.04.2020): 2938. http://dx.doi.org/10.3390/app10082938.
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To address the support problem of large-diameter drilling shafts in the west area of Zhangji coal mine, a thinner shaft lining structure composed of double layers of steel plate and high-performance concrete is proposed herein. Firstly, a series of tests of high-performance concrete preparation were carried out, and the optimized mix ratio of pumping concrete with 60–70 MPa strength for shaft lining of the drilled shaft was obtained. Then, shaft lining models were designed according to the similarity theory, and the mechanical properties of the shaft lining were experimentally studied by loading test. The test results showed that the stress state of concrete in the shaft was obviously improved, and the compressive strength of concrete was increased by 1.97–2.52 times. Finally, the results of the study were applied to a shaft in the control strata of the inlet shaft in the west area of Zhangji coal mine, which made it possible to use the drilling method to construct the shaft. The following field measurement showed that the annular strain of the shaft lining concrete was −487 με, which is far less than the ultimate strain value of C65 concrete, and the shaft lining structure was kept safe and reliable.
6
Yablokov, Aleksey, Ivan Yanin, Aleksey Danilishin und Anatoliy Zuev. „Ansys CFX numerical study of stages centrifugal compressor with low-flow rate coefficient“. MATEC Web of Conferences 245 (2018): 09002. http://dx.doi.org/10.1051/matecconf/201824509002.
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The article presents results of applying the methods of computational fluid dynamics for model low-flow rate stages of centrifugal compressors with flow rate coefficient F = 0.028. The computational domain of a model centrifugal compressor for CFD-simulation consists of the following elements: inlet chamber, impeller, vaneless diffuser, return channel, outlet chamber, shaft seal labyrinth, front and back shroud leakage. Full-scale experimental studies were conducted to model stage 028 in air at an inlet pressure of p* = 1 atm. Numerical research for stage 028 held with flow rate coefficient F=(0.019-0.046) for three variants trailing edge of the impeller. According to the results of numerical research are constructed performances of stages centrifugal compressor and conducted verification of results. Estimated discrepancy between the results of numerical researches on the model with shaft seal labyrinth and without shaft seal labyrinth.
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Liu, Peng, Zheng Lin Liu, Sheng Dong Zhang, Bo Qin und Liang Zhao. „Research on Performance of Stern Shaft Mechanical Seal Based on FLUENT“. Advanced Materials Research 744 (August 2013): 31–34. http://dx.doi.org/10.4028/www.scientific.net/amr.744.31.
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Reasonable assumptions and boundary conditions, the application of CFD method of mechanical seal ring structure analysis and thermal-structural coupling analysis, research on the temperature field and the pressure field distribution of the water flim between moving and the stationary ring . Comparing the change of the maximum temperature and the water film bearing capacity though different inlet velocity and different speed under, known as the fluid inlet speed increases, the maximum temperature of the sealing water film gradually decreased, the bearing capacity gradually increased; as the stern shaft speed increases, the sealing water film maximum temperature gradually reduced, and the bearing capacity of the sealing water film is gradually increased. In this paper, the research to maintain the good performance of the stern shaft mechanical seal has important significance and role.
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Yang, Chun Xia, Meng Tian Lu, Yuan Zheng, Xiao Qing Tian und Yu Quan Zhang. „Inlet Passage’s Development and Optimization of New Tidal Unit-Shaft Tubular Turbine“. Applied Mechanics and Materials 607 (Juli 2014): 312–16. http://dx.doi.org/10.4028/www.scientific.net/amm.607.312.
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A new type of tidal unit-vertical shaft tubular turbine is designed with high efficiency, large flow rate and low water head ,which has large power under the 2~3 meters water head. According to the data of the being installed tidal units and principles of tubular turbine’s design, the high efficiency vertical shaft tubular turbine was designed under large discharge and low head, which was suitable for the tidal power station. The design also considered the requirements of turbine’s size and the details of flow through the whole flow passage were attained. The turbine’s property was predicted by the 3-d numerical simulation software on the whole flow passage. Moreover, the influences of vertical shaft’s sizes were analyzed. And the terminal of vertical shaft with or without transverse brace and longitudinal brace were analyzed to get the influence. Considering the hydraulic performance of various methods, the best guide vane opening was chosen. The results show that, the turbine unit has the best performance on efficiency, hydraulic loss, etc. with the guide vane opening 62°, meeting the power station’s design requirements. The results show that the optimal designed flow passage’s efficiency reaches up to 88.4%, the flow rate becomes much larger and the power reaches 174.63kW. Without partial vortex, the flow pattern is smooth through the whole passage also with lower hydraulic loss.
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Sanaye, Sepehr, und Salahadin Hosseini. „Off-design performance improvement of twin-shaft gas turbine by variable geometry turbine and compressor besides fuel control“. Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 234, Nr. 7 (03.12.2019): 957–80. http://dx.doi.org/10.1177/0957650919887888.
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A novel procedure for finding the optimum values of design parameters of industrial twin-shaft gas turbines at various ambient temperatures is presented here. This paper focuses on being off design due to various ambient temperatures. The gas turbine modeling is performed by applying compressor and turbine characteristic maps and using thermodynamic matching method. The gas turbine power output is selected as an objective function in optimization procedure with genetic algorithm. Design parameters are compressor inlet guide vane angle, turbine exit temperature, and power turbine inlet nozzle guide vane angle. The novel constrains in optimization are compressor surge margin and turbine blade life cycle. A trained neural network is used for life cycle estimation of high pressure (gas generator) turbine blades. Results for optimum values for nozzle guide vane/inlet guide vane (23°/27°–27°/6°) in ambient temperature range of 25–45 ℃ provided higher net power output (3–4.3%) and more secured compressor surge margin in comparison with that for gas turbines control by turbine exit temperature. Gas turbines thermal efficiency also increased from 0.09 to 0.34% (while the gas generator turbine first rotor blade creep life cycle was kept almost constant about 40,000 h). Meanwhile, the averaged values for turbine exit temperature/turbine inlet temperature changed from 831.2/1475 to 823/1471°K, respectively, which shows about 1% decrease in turbine exit temperature and 0.3% decrease in turbine inlet temperature.
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Yang, Peiji, Qi Yuan und Runlin Chen. „Experimental research on the tilting pad bearing under the high temperature of inlet oil“. Industrial Lubrication and Tribology 70, Nr. 6 (13.08.2018): 935–41. http://dx.doi.org/10.1108/ilt-01-2017-0021.
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Purpose The purpose of this study is to analyze the influence of high-temperature inlet oil on the comprehensive performance of tilting-pad bearing. Design/methodology/approach Taking a tilting-pad bearing under high temperature of inlet oil in a natural gas compressor as an example, the experimental system was developed for the tilting-pad bearing applied in a real machine, and the experiment was performed. The bearing lubricating properties under different high temperatures of inlet oil were obtained, including oil film thickness on the pivot, temperature rise and the shaft vibration values at the bearing positions. Findings The experimental results showed that the vibration, the oil film thickness on the pivot and the pad temperature were not sensitive to the change in temperature of the inlet oil, but vibrations were observed under the specific speed. At the same speed, when oil temperature changed by 1°C, the bearing temperature rise did not exceed 0.2°C and change in oil film thickness on the pivot was 1 µm. The test results of the actual unit are in good agreement with the experimental results. Originality/value The vibration measurement scheme was presented, and an indirect measurement method of fulcrum thickness was proposed. The practicability of the measurement method and the accuracy of test results were verified by the comparison of the test results of the shaft vibration, the bearing pad temperature, the fulcrum oil film thickness and the theoretical calculation results. This study will provide an important reference for designing a tilting-pad bearing with high-temperature inlet oil.
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Tucker, P. G., und P. S. Keogh. „A Generalized Computational Fluid Dynamics Approach for Journal Bearing Performance Prediction“. Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 209, Nr. 2 (Juni 1995): 99–108. http://dx.doi.org/10.1243/pime_proc_1995_209_412_02.
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The use of computational fluid dynamics (CFD) techniques enables performance predictions of bearing designs to be made when the usual operating assumptions of the Reynolds equation Jail to hold. This paper addresses the application of a full three-dimensional thermohydrodynamic CFD approach to journal bearings. The journal/shaft may extend beyond the bearing length and the rotation effect is accounted for in the thermal transport process. A circumferentially uniform shaft surface temperature is not assumed. Cavitation modelling is based on averaged lubricant/vapour properties and does not set pressures directly, allowing sub-ambient pressures to be predicted. Lubricant inlet grooves are incorporated with conservation of mass and the possibility of backflow. The modelling is validated against published experimental work on fully circumferential, single inlet and two-inlet circular bore bearings. The predicted and experimental results are in general agreement, although the predicted cyclic variation of journal surface temperature is less than the experimental value. However, an assumption in the predictions was of a non-orbiting journal. The techniques developed may, in principle, be extended to the orbiting journal case providing a dynamic cavitation model can be formulated.
12
Chen, Xi Shan, und Yong Liang Zhang. „Pre-Cooling the Inlet Airflow of the Mine Utilizing the Shallow Rock Low Temperature Resource“. Advanced Materials Research 868 (Dezember 2013): 241–50. http://dx.doi.org/10.4028/www.scientific.net/amr.868.241.
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In order to reduce operating temperature of deep mine, took shallow rock layer low temperature effect of mine as natural energy (cold) source in the spring and summer, used shallow abandoned waste roadway as cooling space to carry out research on deep cooling ventilation. Built model of heat and moisture exchange between inlet airflow and low temperature rock layer, carried out numerical simulation for inlet airflow cooling process of specific test mine. At the same time, inlet airflow cooling results of the experimental mine was gotten through testing and verifying. Results show: using this natural energy (cold)source that shallow rock layer low temperature effect of metal mine and abandoned resource of roadway, shaft, slop etc. cooling the inlet airflow instead of artificial refrigeration to auxiliary mine deep cooling in the spring and summer have practical saving energy significance and better applied prospect.
13
Sayma, A. I., M. Vahdati, S. J. Lee und M. Imregun. „Forced response analysis of a shaft-driven lift fan“. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 217, Nr. 10 (01.10.2003): 1125–37. http://dx.doi.org/10.1243/095440603322517144.
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The aim of this paper is to give an overview of the multi-bladerow forced response analyses carried out on a shaft-driven lift fan. The lift fan, used for vertical landing and take-off, is situated behind the cockpit and contains seven bladerows, of which two are counter-rotating rotors. The aim of the analysis is to determine the maximum vibration amplitudes of the two rotor bladerows for a range of configurations and speeds. Unlike typical axial-flow compressors, a significant part of the unsteady aerodynamic excitation is due to the distortion of the inlet flow over the cockpit and fuselage, a situation that creates several low engine-order harmonics. In addition, the main blade passing harmonics, arising from the bladerows immediately upstream, also need to be considered. Both the blading and the inlet geometry are difficult to discretize, the former due to overlapping bladerows and the latter due to complexity of the aircraft geometry including the louvred doors. The forced response analysis methodology is based on using an integrated aeroelasticity model which combines a non-linear, time-accurate, viscous unsteady flow representation with a modal model of the structure. The rotor vibration response was assessed at various shaft speeds for both stationary aircraft and at a number of flight speeds and yaw angles. Wherever possible, the findings were compared against measured experimental data and good agreement was obtained in most cases. The main conclusion is the feasibility of being able to use a numerical tool as an integral part of the design process, a route that allows a much more efficient coverage of the flight envelope compared to actual rig and engine tests.
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Brun, K., und R. D. Flack. „Laser Velocimeter Measurements in the Turbine of an Automotive Torque Converter: Part I—Average Measurements“. Journal of Turbomachinery 119, Nr. 3 (01.07.1997): 646–54. http://dx.doi.org/10.1115/1.2841170.
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The three-dimensional average velocity field in an automotive torque converter turbine was examined. Two significantly different operating conditions of the torque converter were tested: the 0.065 and 0.800 turbine/pump speed ratio. Velocities were measured using a one-directional, frequency-shifted laser velocimeter. The instantaneous angular positions of the torque converter turbine and pump were recorded using digital shaft encoders. Shaft encoder information and velocities were correlated to generate average velocity blade-to-blade profiles and velocity vector plots. Measurements were taken in the inlet, quarter, mid, and exit planes of the turbine. From the experimental velocity measurements, mass flows, turbine output torque, average vorticities, viscous dissipation, inlet incidence flow angles, and exit flow angles were calculated. Average mass flows were 23.4 kg/s and 14.7 kg/s for the 0.065 and 0.800 speed ratios, respectively. Velocity vector plots for both turbine/pump speed ratios showed the flow field in the turbine quarter and midplanes to be highly nonuniform with separation regions and reversed flows at the core-suction corner. For the conditions tested, the turbine inlet flow was seen to have a high relative incidence angle, while the relative turbine exit flow angle was close to the blade angle.
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Si, Qiaorui, Shouqi Yuan, Jianping Yuan, Chuan Wang und Weigang Lu. „Multiobjective Optimization of Low-Specific-Speed Multistage Pumps by Using Matrix Analysis and CFD Method“. Journal of Applied Mathematics 2013 (2013): 1–10. http://dx.doi.org/10.1155/2013/136195.
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The implementation of energy-saving and emission-reduction techniques has become a worldwide consensus. Thus, special attention should be provided to the field of pump optimization. With the objective of focusing on multiobjective optimization problems in low-specific-speed pumps, 10 parameters were carefully selected in this study for anL27(310) orthogonal experiment. The parameters include the outlet width of the impeller blade, blade number, and inlet setting angle of the guide vane. The numerical calculation appropriate for forecasting the performance of multistage pumps, such as the head, efficiency, and shaft power, was analyzed. Results were obtained after calculating the two-stage flow field of the pump through computational fluid dynamics (CFD) methods. A matrix method was proposed to optimize the results of the orthographic experiment. The optimal plan was selected according to the weight of each factor. Calculated results indicate that the inlet setting angle of the guide vane influences efficiency significantly and that the outlet angle of blades has an effect on the head and shaft power. A prototype was produced with the optimal plan for testing. The efficiency rating of the prototype reached 58.61%; maximum shaft power was within the design requirements, which verifies that the proposed method is feasible for pump optimization.
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Bai, Ping. „Design and Experimental Research on the Sealing Structure of High-Pressure Gear Pump“. Advanced Materials Research 468-471 (Februar 2012): 807–10. http://dx.doi.org/10.4028/www.scientific.net/amr.468-471.807.
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Due to great pressure difference between inlet and outlet, high-pressure gear pump can cause unbalanced radial force, which results in serious wearing between axle journal of drive shaft and bearing-hole, non-ideal dynamic characteristics, and drop of volumetric efficiency after long run. This paper introduces a new sealing structure. Based on this structure, a high-pressure oil reservoir is installed on the wall of the inner-hole of floating plate for radial support and lubricating, which can effectively reduce shaft wearing and noise, and improve working dynamic characteristics of high-pressure gear pump.
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Boncompain, R., M. Fillon und J. Frene. „Analysis of Thermal Effects in Hydrodynamic Bearings“. Journal of Tribology 108, Nr. 2 (01.04.1986): 219–24. http://dx.doi.org/10.1115/1.3261166.
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A general THD theory and a comparison between theoretical and experimental results are presented. The generalized Reynolds equation, the energy equation in the film, and the heat transfer equation in the bush and the shaft are solved simultaneously. The cavitation in the film, the lubricant recirculation, and the reversed flow at the inlet are taken into account. In addition, the thermoelastic deformations are also calculated in order to define the film thickness. Good agreement is found between experimental data and theoretical results which include thermoelastic displacements of both the shaft and the bush.
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Yang, Zhou, Jinbu Yin, Yangliang Lu, Zhiming Liu, Haoyu Yang und Genhai Xu. „Three-Dimensional Flow of a Vortex Drop Shaft Spillway with an Elliptical Tangential Inlet“. Water 13, Nr. 4 (15.02.2021): 504. http://dx.doi.org/10.3390/w13040504.
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Vortex drop shaft (VDS) spillways are eco-friendly hydraulic structures used for safely releasing flood. However, due to the complexity of the three-dimensional rotational flow and the lack of suitable measuring devices, current experimental work cannot interpret the flow behavior reliably inside the VDS spillway, consequently experimental and CFD study on a VDS spillway with an elliptical tangential inlet was conducted to further discern the interior three-dimensional flow behavior. Hydraulic characteristics such as wall pressure, swirl angle, annular hydraulic height and Froude number of the tapering section are experimentally obtained and acceptably agreed with the numerical prediction. Results indicated that the relative dimensionless maximum height of the standing wave falls off nearly linearly with the increasing Froude number. Nonlinear regression was established to give an estimation of the minimum air-core rate. The normalized height of the hydraulic jump depends on the flow phenomena of pressure slope. Simulated results sufficiently reveal the three-dimensional velocity field (resultant velocity, axial velocity, tangential velocity and radial velocity) with obvious regional and cross-sectional variations inside the vortex drop shaft. It is found that cross-sectional tangential velocity varies, resembling the near-cavity forced vortex and near-wall free vortex behavior. Analytic calculations for the cross-sectional pressure were developed and correlated well with simulated results.
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Corvaglia, Alessandro, Massimo Rundo, Paolo Casoli und Antonio Lettini. „Evaluation of Tooth Space Pressure and Incomplete Filling in External Gear Pumps by Means of Three-Dimensional CFD Simulations“. Energies 14, Nr. 2 (09.01.2021): 342. http://dx.doi.org/10.3390/en14020342.
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The paper presents the computational fluid dynamics simulation of an external gear pump for fluid power applications. The aim of the study is to test the capability of the model to evaluate the pressure in a tooth space for the entire shaft revolution and the minimum inlet pressure for the complete filling. The model takes into account the internal fluid leakages and two different configurations of the thrust plates have been considered. The simulations in different operating conditions have been validated with proper high dynamics transducers measuring the internal pressure in a tooth space for the entire shaft revolution. Steady-state simulations have been also performed in order to detect the fall of the flow rate due to the incomplete filling of the tooth spaces when the inlet pressure is reduced. It has been demonstrated that, despite the need of a compromise for overcoming the limitation of considering fixed positions of the gears’ axes and of the thrust plates, significant results can be obtained, making the CFD approach very suitable for such analyses.
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Corvaglia, Alessandro, Massimo Rundo, Paolo Casoli und Antonio Lettini. „Evaluation of Tooth Space Pressure and Incomplete Filling in External Gear Pumps by Means of Three-Dimensional CFD Simulations“. Energies 14, Nr. 2 (09.01.2021): 342. http://dx.doi.org/10.3390/en14020342.
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The paper presents the computational fluid dynamics simulation of an external gear pump for fluid power applications. The aim of the study is to test the capability of the model to evaluate the pressure in a tooth space for the entire shaft revolution and the minimum inlet pressure for the complete filling. The model takes into account the internal fluid leakages and two different configurations of the thrust plates have been considered. The simulations in different operating conditions have been validated with proper high dynamics transducers measuring the internal pressure in a tooth space for the entire shaft revolution. Steady-state simulations have been also performed in order to detect the fall of the flow rate due to the incomplete filling of the tooth spaces when the inlet pressure is reduced. It has been demonstrated that, despite the need of a compromise for overcoming the limitation of considering fixed positions of the gears’ axes and of the thrust plates, significant results can be obtained, making the CFD approach very suitable for such analyses.
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Hu, Song, Pan Jian Feng, Ai Kun Tang, Xia Shao und Yang Xian Liu. „Analysis of Criterion Number of Heat Transfer in Micro Catalytic Combustion Process“. Applied Mechanics and Materials 316-317 (April 2013): 53–59. http://dx.doi.org/10.4028/www.scientific.net/amm.316-317.53.
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Based on a detailed chemical reaction mechanism including gas phase reaction and surface catalytic reaction, adopting the CFD software to simulate the combustion process of premixed hydrogen-oxygen in a sub-millimeter burner, and introducing a calculating model of criterion number of heat transfer, a comparative analysis of surface catalytic conditions is performed to find out the heat transfer characteristics during combustion process. The simulation results show that the effects of inlet velocity on Nux number vary regionally when gas phase reaction combined with surface catalytic reaction. As inlet velocity increases, Nux number firstly increases and then decreases in low velocity. While in high inlet velocity, the Nux number of entrance region is in the negative half shaft that means the direction of heat transfer has changed. Inlet temperature has comparatively less effects on Nux number in micro catalytic combustion process under the computational conditions. When the temperature is fixed, the Nux number with catalytic is higher than those without catalytic and the difference is more obvious in lower temperature. Key words:Micro combustion, Catalytic combustion, Criterion number of heat transfer, Dimensionless analysis
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Andrisano, A. O. „An Experimental Investigation on the Rotating Journal Surface Temperature Distribution in a Full Circular Bearing“. Journal of Tribology 110, Nr. 4 (01.10.1988): 638–45. http://dx.doi.org/10.1115/1.3261706.
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A method is described for measuring the rotating shaft surface temperature in a full circular bearing. The experimental measurements related to a journal bearing with a unitary length/diameter ratio, are reported. Contrary to the commonly held assumption, the shaft surface temperature is found to remain not quite constant, but to fluctuate during the journal revolution; the value of the temperature in the revolution appears to be maximum about the minimum film thickness. Typical surface temperature distribution scope traces, circumferential variation amplitudes of the surface temperature and increases in the mean revolution value of the journal surface temperature with respect to that of the inlet lubricant oil, are plotted versus shaft speed, lubricant viscosity and bearing load. The journal speed and lubricant viscosity appear to significantly affect the rotating shaft surface temperature as well as its fluctuation in the revolution; the effect of the bearing load is less influential.
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Filinov, Evgeny, Andrey Tkachenko, Hewa Hussein Omar und Viktor Rybakov. „Increase the Efficiency of a Gas Turbine Unit for Gas Turbine Locomotives by Means of Steam Injection into the Flow Section“. MATEC Web of Conferences 220 (2018): 03010. http://dx.doi.org/10.1051/matecconf/201822003010.
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In the modern world of railways, electrification is given great importance. Currently, more than 50% of all freight traffic carried out by electric traction. However, today, about half of the railways are not electrified, so it is necessary to use thermal engines to drive the locomotive. One of the possible variant is use gas turbine unit. The power of the gas turbine unit is given to the electric generator, and the electric motors drive the locomotive. In the present paper, as a power plant of a gas turbine locomotive, considered gas turbine unit with a twin -shaft gas generator of two schemes: 1- with steam supply to the inlet of the high-pressure turbine (into the combustion chamber) and 2- with steam supply to inlet of the free turbine. By CAE system of ASTRA, Collaboration operation lines calculated for different variants of steam injection. When the steam injected into the inlet of a free turbine and a high-pressure turbine. in the case of steam supply to the input of the free turbine and the high-pressure turbine there is a significant shift in Collaboration operation lines, which can lead to a decrease in the gas-dynamical stability of the compressors, and efficiency. To maintain the position of Collaboration operation lines, was applied the correction of the throughput capacity of free turbine nozzle vanes (by 15%). In the case of steam supply to the inlet of a free turbine, to ensure gas-dynamic stability of the compressors, a change in the throughput capacity of its nozzle vanes is required.
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Li, WenJing, ShengHua Zou, WanXin Yang und Qi Hu. „Model of Heat and Mass Exchange between a Downcast Shaft and the Air Flow to the Mine“. Geofluids 2020 (08.10.2020): 1–10. http://dx.doi.org/10.1155/2020/8853839.
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Mining activities have increased owing to the rise in the social demand for minerals. Thermal hazards have become a major health and safety consideration in mines. The thermal environment of a working face is related to the air parameters at the bottom of shaft. The objective of this study is to accurately predict the air temperature at the bottom of a shaft in a mine with the ventilation time over 3 years. For this purpose, a mathematical model of the heat and mass exchange between the surrounding rock of the shaft and the downcast air is established by utilizing the finite volume method. The C++ languages are used for numerical calculations. The results are in agreement with the measured data. The effects of the relative humidity of air at the inlet of the shaft, the surface moisture coefficient of the shaft surface, and the physical parameters of the rock on the air parameters at the shaft bottom are studied in detail. Equations for calculating the enthalpy increase of air per 100 m in shaft with the depth of 1300 m were established by using cluster analysis. This equation provides a theoretical basis for predicting the air parameters along the shaft with the ventilation time over 3 years.
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Gao, Jian Hua, und Ying Yun Huang. „Effect of Ambient Temperature on Three-Shaft Gas Turbine Performance under Different Control Strategy“. Advanced Materials Research 424-425 (Januar 2012): 276–80. http://dx.doi.org/10.4028/www.scientific.net/amr.424-425.276.
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Gas turbine is sensitive to ambient temperature. Different ambient temperature could change the state of the inlet air of compressor and make the gas turbine work in off design conditions. Research the effect of ambient temperature on gas turbine performance is valuable to the long-term safe operation of gas turbine. In this paper, a thermodynamic model of a simple cycle gas turbine which has three shafts was established, and steady-state performance simulation under different ambient temperature was carried out. In the two conditions of 1.0 and 0.35 work states, the effect of ambient temperature on thermodynamic parameters, specific power and thermal efficiency of gas turbine were analyzed. The result shows that: effect of ambient temperature on three-shaft gas turbine is different under different work state, and relevant factors must be considered to select the appropriate control strategy
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Hashmi, Muhammad Baqir, Tamiru Alemu Lemma und Zainal Ambri Abdul Karim. „Investigation of the Combined Effect of Variable Inlet Guide Vane Drift, Fouling, and Inlet Air Cooling on Gas Turbine Performance“. Entropy 21, Nr. 12 (01.12.2019): 1186. http://dx.doi.org/10.3390/e21121186.
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Variable geometry gas turbines are susceptible to various malfunctions and performance deterioration phenomena, such as variable inlet guide vane (VIGV) drift, compressor fouling, and high inlet air temperatures. The present study investigates the combined effect of these performance deterioration phenomena on the health and overall performance of a three-shaft gas turbine engine (GE LM1600). For this purpose, a steady-state simulation model of the turbine was developed using a commercial software named GasTurb 12. In addition, the effect of an inlet air cooling (IAC) technique on the gas turbine performance was examined. The design point results were validated using literature results and data from the manufacturer’s catalog. The gas turbine exhibited significant deterioration in power output and thermal efficiency by 21.09% and 7.92%, respectively, due to the augmented high inlet air temperature and fouling. However, the integration of the inlet air cooling technique helped in improving the power output, thermal efficiency, and surge margin by 29.67%, 7.38%, 32.84%, respectively. Additionally, the specific fuel consumption (SFC) was reduced by 6.88%. The VIGV down-drift schedule has also resulted in improved power output, thermal efficiency, and the surge margin by 14.53%, 5.55%, and 32.08%, respectively, while the SFC decreased by 5.23%. The current model can assist in troubleshooting the root cause of performance degradation and surging in an engine faced with VIGV drift and fouling simultaneously. Moreover, the combined study also indicated the optimum schedule during VIGV drift and fouling for performance improvement via the IAC technique.
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Fang, Yan Kai, und Limin Chen. „Performance Analysis on Electrical Aided Turbocharged System“. Applied Mechanics and Materials 34-35 (Oktober 2010): 1946–50. http://dx.doi.org/10.4028/www.scientific.net/amm.34-35.1946.
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A turbocharger is fitted to a diesel in order to enhance the inlet charge pressure, hence increasing the fresh air in the cylinder, then more fuel can be injected into the cylinder and sequentially more engine power can put out. The electrical aided turbocharged system is a mechanism adding a high speed electronic motor into a turbocharger shaft. The electronic motor can work as a motor to drive the turbocharger shaft and as a generator to generate electricity energy to storage energy. According to certain constraint conditions, the controlling strategy of the hybrid turbocharged system is presented. The simulation results about key work points reveal that controlling the turbocharged engine following the strategy can enhance the engine performance.
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Liu, Ying-Yuan, Yi-Ran Li und Le-Qin Wang. „Experimental and theoretical studies on the pressure fluctuation of an internal gear pump with a high pressure“. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 233, Nr. 3 (12.02.2018): 987–96. http://dx.doi.org/10.1177/0954406218758796.
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In this paper, the flow ripple equation is derived to analyze the effect of working condition on pressure pulsations of an internal gear pump. Results indicate that working pressure has a significant effect on pressure fluctuation of the internal gear pump, while the rotating speed has a complex influence on the pressure pulsation behavior. Then, pressure pulsations of the internal gear pump under different working conditions are discussed by experimental investigations. Results show that the internal gear pump taken for analysis has a low-pressure pulsation at a high working pressure and a relatively high rotational speed. Regarding the frequency spectrum of the pressure pulsation, the dominant frequency is Z* fn, i.e. the product of the tooth number of the driving gear (gear shaft) and its rotational frequency for many working conditions, caused by the inevitable unsteady discharge process of gear pumps. It transforms to the rotational frequency of the gear shaft ( fn) for a high rotational speed or a high operating pressure, but to the rotating frequency of the internal gear ring (2/3 fn) only for a high operating pressure. The occurrence of the two frequencies (2/3 fn and fn) may result from the deformation of the gear ring and the gear shaft under the unbalanced radial forces caused by a high working pressure. Moreover, the frequency spectrum of the inlet pressure pulsation presents some differences from that of the outlet pressure pulsation. This is because the inlet pressure may be influenced by cavity generated at the suction side of the pump.
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Kirk, R. Gordon. „A Method for Calculating Labyrinth Seal Inlet Swirl Velocity“. Journal of Vibration and Acoustics 112, Nr. 3 (01.07.1990): 380–83. http://dx.doi.org/10.1115/1.2930519.
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The results of numerous investigators have shown the importance of inlet swirl on the calculated dynamic stiffness and stability of labyrinth seals. These results have not included any calculation of inlet leakage of swirl as a function of complex disk geometry including the sealing conditions of the given seal. This paper outlines a method of calculating the inlet swirl at the entrance of the labyrinth seal by introducing a radial chamber which when added to the axial flow solution allows the prediction of the gas swirl as it flows radially from the stage tip along the disk face inward to the seal location. This solution is consistent with the leakage model for the seal and allows rapid evaluation of seal designs. For a centrifugal compressor, this added feature permits the designer to include the flow path from the impeller discharge, down the back of the disk or front of the cover, then into the shaft seal or eye packing, respectively. The solution includes the friction factors of both the disk and stationary wall with account for mass flow rate and calculation of radial pressure gradients by a free vortex solution. The results of various configurations are discussed and comparisons made to other published results of disk circumferential velocity swirl.
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Novecosky, T. „Axial Inlet Conversion to a Centrifugal Compressor With Magnetic Bearings“. Journal of Engineering for Gas Turbines and Power 116, Nr. 1 (01.01.1994): 152–55. http://dx.doi.org/10.1115/1.2906784.
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NOVA’s Alberta Gas Transmission Division transports natural gas via pipeline throughout the province of Alberta, Canada, exporting it to eastern Canada, United States, and British Columbia. There is a continuing effort to operate the facilities and pipeline at the highest possible efficiency. One area being addressed to improve efficiency is compression of the gas. By improving compressor efficiency, fuel consumption and hence operating costs can be reduced. One method of improving compressor efficiency is by converting the compressor to an axial inlet configuration, a conversion that has been carried out more frequently in the past years. Concurrently, conventional hydrodynamic bearings have been replaced with magnetic bearings on many centrifugal compressors. This paper discusses the design and installation for converting a radial overhung unit to an axial inlet configuration, having both magnetic bearings and a thrust reducer. The thrust reducer is required to reduce axial compressor shaft loads, to a level that allows the practical installation of magnetic bearings within the space limitations of the compressor (Bear and Gibson, 1992).
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Ohm, Tea In, Jong Seong Cae, Meng Yu Zhang und Jin Chul Joo. „Computational Fluid Dynamics Modeling and Field Applications of Non-Powered Hydraulic Mixing in Water Treatment Plants“. Water 12, Nr. 4 (26.03.2020): 939. http://dx.doi.org/10.3390/w12040939.
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In this study, non-powered hydraulic mixing with three layers of baffles and holes was evaluated as an alternative to vertical shaft impellers in a rapid mixing process through both computational fluid dynamics (CFD) modeling and field applications. From the CFD modeling, the turbulence (i.e., vortex rings) caused by excess kinetic energy between the inlet and second-layer baffle ensures rapid mixing of the coagulants throughout the total water flow and overcomes the damping effect of the components in a mixing basin. Although optimal inlet velocity needs to be investigated for sufficient mixing between coagulants and pollutants in raw water with relatively low energy consumption and maintenance costs, non-powered hydraulic mixing developed in this study was proved to create strong turbulence and can be applied in any water treatment plants that involves coagulation-flocculation processes. Based on the comparison of the water quality between two water treatment plants using identical raw water and coagulant operated from 2014 to 2016, no difference in water quality of treated water indicated that non-powered hydraulic mixing can be replaced with vertical shaft impellers, hence, both energy consumption and maintenance costs can be reduced. Further study is warranted to optimize non-powered hydraulic mixing for the tradeoff between mixing efficiency and energy consumption in the water treatment plants.
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Hwang, Sung Hoon, Soo Hyoung Yoon und Tong Seop Kim. „Design and Off-Design Characteristics of the Alternative Recuperated Gas Turbine Cycle With Divided Turbine Expansion“. Journal of Engineering for Gas Turbines and Power 129, Nr. 2 (01.02.2006): 428–35. http://dx.doi.org/10.1115/1.2364195.
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In order to fully address the characteristics of the alternative recuperated cycle with divided turbine expansion, both design and off-design analyses have been performed. Two types of mechanical design are assumed: two shaft and single shaft. In particular, optimal pressure ratio division between the high- and low-pressure turbines is evaluated for the single-shaft configuration. It is predicted that the alternative recuperated cycle hardly exhibits sensible design efficiency advantage over the conventional recuperated cycle for moderate turbine inlet conditions and with usual component performances. An advantage of the alternative cycle with single-shaft design is that thermal efficiency is less sensitive to compressor pressure ratio compared to other configurations, and we can also have flexibility in the turbine division without much efficiency loss. The part load analyses have been carried out with the aid of realistic component maps and models for off-design operation. In addition to the general fuel only control, a variable speed control is assumed as the part load operating strategy of the single-shaft configuration. Obvious advantage with the alternative cycle is observed in the variable speed operation of the single-shaft design. With this strategy, the part load efficiency of the alternative cycle is far superior to the conventional cycle. Almost constant efficiency is predicted for a wide power range.
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Abhulimen, Abel Edeowede, Mathias Usman Bonet, Olukayedo Oyekunle, Nnorom Achara und Wunuken Carlos Solomon. „An Inquisition on the Combined Effects of Ambient Temperature and Relative Humidity on The Performance of a Uniform Speed Single Shaft Gas Turbine in Tropical Monsoon Climate, using GPAL“. European Journal of Engineering Research and Science 5, Nr. 6 (29.06.2020): 736–44. http://dx.doi.org/10.24018/ejers.2020.5.6.1946.
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This paper investigates the combined effects of Ambient Temperature and Relative Humidity on the performance of a uniform speed single shaft Gas Turbine, sited in Tropical Monsoon climate. A single shaft gas turbine simulator (known as GPAL) from Gas path Analysis ltd was employed. The City of Portharcourt, Nigeria, was chosen to represent the tropical monsoon climate, with its climatic data of monthly ambient temperature and relative humidity obtained from Koppen. With parameters like speed, reference power, inlet and exhaust losses kept constant, the ambient temperature and relative humidity were continually varied according to their climatic values. Each time, the performance of the gas turbine was simulated and parameters such as; Efficiency, Turbine power and Net power output, Turbine inlet Temperature and Exhaust Gas Temperature, as well as Specific fuel consumption were monitored. The environmental impact of the gas turbine was equally assessed in terms of Carbon (IV) Oxide (CO2) emission in Tonnes/day and in Kg/MWhr, NOX emission and Carbon Monoxide (CO) emission. The results of the study indicate that it is most efficient and productive to operate the gas turbine in Portharcourt in the months of January and December whereas it is least efficient in the month of April. Whereas CO emission was relatively low and uniform throughout the year, the highest specific fuel consumption was recorded in April.
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Hutchinson, Peter J., Alexander Balog und Shad E. Hoover. „Microgravity Mapping of an Inception Doline Shaft System“. Environmental and Engineering Geoscience 26, Nr. 2 (27.05.2020): 217–25. http://dx.doi.org/10.2113/eeg-2294.
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ABSTRACT Reactivation of an inception doline shaft system through anthropogenic actions, precipitation, and possibly seismic activity induced subsidence in a hospital emergency room that was under construction in State College, PA. The convergence of Tropical Storm Lee and Hurricane Irene is interpreted to have caused the building's brick edifice to fall and induce vertical shifts in the reinforced concrete entrance floor slab. Microgravity mapping of the existing hospital emergency room entrance; the emergency room building under construction; and the parking lot in front of the emergency room entrance documented the presence of a doline shaft system (i.e., inter-connected sinkhole). Groundwork for the construction of the new emergency room included grading and leveling of the property. Surface water runoff entered the construction site from a parking lot that sloped toward the addition and to a non-functioning stormwater inlet. The grading for the new construction exposed an open fracture for surface runoff. Subsequent channeling of surface water to the conduit provided drainage for surface runoff, but it also initiated subsidence throughout the existing structure and the addition that was under construction. Engineering rehabilitation included a limited mobility (LM) grout program to plug subsoil fracture karren drainage systems and stabilize the surface. Drilling progressed in four stages, initially focusing on areas of greatest subsidence. In total, 60 injection points were completed to a mean depth of 24 m below grade in an area measuring approximately 370 m2. During LM grouting, 867 m3 of a sand-and-cement grout mixture were injected to stabilize the area.
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Timushev, S. F., und A. A. Frolov. „Automatic Unloading Liquid Rocket Engine Fuel Feed System Booster Pump Radial Thrust Bearings from Axial Force“. Proceedings of Higher Educational Institutions. Маchine Building, Nr. 7 (736) (Juni 2021): 54–61. http://dx.doi.org/10.18698/0536-1044-2021-7-54-61.
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Increasing the suction capacity, efficiency and energy parameters of high-speed pumps is an important task in the development of power systems in the aerospace industry, as well as in their application in energy and oil production. With improved cavitation properties, the pumps can operate at a higher shaft speed, and at its given value - with lower cavitation reserves, i.e. at a reduced inlet pressure. When the shaft speed increases, the pump weight and overall dimensions decrease. To increase the anti-cavitation qualities of pumps in the power system, auxiliary (booster) pumping units are used, creating the pressure necessary for the cavitation-free operation of high-pressure and high-speed main pumps of the engine fuel supply system. In accordance with its purpose, the booster pump must provide the required supply pressure of the specified flow rate at the lowest possible liquid pressure at the inlet. At the same time, the efficiency of the booster pump unit should be maximum, and the overall dimensions and weight should be minimal. The last two characteristics predetermine the maximum possible number of revolutions of the pump shaft. Ensuring the operability of the ball-bearing supports of the fuel supply units is one of the most important and complex tasks in the development of modern and promising liquid rocket engines (LRE), especially reusable ones. This task has always been one of the priorities in the fine-tuning the fuel feed units of such engines. The article proposes a method for calculating and controlling the unloading liquid rocket engine booster pump radial thrust bearings from axial force. The method can be applied in the entire range of liquid rocket engine calculations. The further development of this work will be mathematical modeling of the operation of the booster pump automatic axial force unloading.
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Li, Jun, Hal Gurgenci, Jishun Li, Lun Li, Zhiqiang Guan und Fang Yang. „Optimal design to control rotor shaft vibrations and thermal management on a supercritical CO2 microturbine“. Mechanics & Industry 22 (2021): 22. http://dx.doi.org/10.1051/meca/2021023.
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Supercritical carbon dioxide (SCO2) Brayton cycle microturbine can be used for the next generation of solar power. In order to comprehensively optimize the supporting system and cooling device parameters of Brayton cycle shafting, the concept of chaos interval is introduced by chaotic mapping, and the CIMPSO algorithm is proposed to optimize the multi-objective rotor system model with nonlinear variables.The results show that the resonance amplitude of the optimized model is effectively attenuated, and the critical speed point is far away from the working speed, which shows the robustness of the optimization algorithm. Finally, based on arbitrary several sets of optimization solutions and empirical parameters, the finite element model of shafting is established for simulation, and the results show that the optimized solution has certain guiding significance for the design of the rotor system.The cooling device is designed and simulated by CFD method based on the optimal solution set. Both the inlet boundary conditions of given pressure (1 MPα) and given mass flow rate (0.1 kg/s) numerical calculations were carried out to characterize the cooling performance, for different jet impingement configurations (Hr/din = 0.0125 ∼ 5).Several sets of analyses show the strong effects of the jet-to-target spacing (Hr/din) on the rotor thermal performance at a given diameter (din) of the nozzle. Average temperature (Tc) at the free end of the rotor show that, as jet-to-target distance decreases (0.0125 ≤ Hr/din ≤ 0.33), the heat dissipation efficiency of the cooling device with the given pressure boundary condition tends to decrease, while the conclusion is opposite when the inlet boundary condition is set to the given mass flow rate. And there is an interval for the optimal combination (Hr/din) to promote the cooling efficiency.
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Duan, Xiaohui, Fangping Tang, Wenyong Duan, Wei Zhou und Lijian Shi. „Experimental investigation on the correlation of pressure pulsation and vibration of axial flow pump“. Advances in Mechanical Engineering 11, Nr. 11 (November 2019): 168781401988947. http://dx.doi.org/10.1177/1687814019889473.
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Pressure and vibration displacement value are relatively measured by 14 pressure sensors and 2 vibration sensors distributing inside the tank-type model axial flow pump device under different flow rates. By comparison, it is found that the pressure pulsation on the inlet of the impeller is the main cause of hydraulic induced vibration of the pump device, and it is found to have similar amplitude trend with the vertical vibration as the flow rates increases and large correlation coefficient with the horizontal vibration under high flow rates through time-domain analysis. By frequency-domain analysis, it is found that the main frequency of pressure pulsation is three multiplies of the shaft frequency, but it is one multiplies of vertical vibration, and it changes from one multiplies to three multiplies of horizontal vibration. Combining with the analysis of phase-flow rates characteristics of both pressure pulsation and vibration, it is concluded that, for the horizontal vibration, the frequency ingredient of one multiplies ranging from low to high flow rates and three multiplies removing from unstable and high flow rates zone are possibly induced by pressure pulsation on the inlet of impeller, while for the vertical vibration, the frequency ingredient of one multiplies under design flow rates and high flow rates are possibly induced by pressure pulsation on the inlet of impeller. Both the horizontal and vertical vibrations with frequency of two multiplies have little relationship with the pressure pulsation on the inlet of impeller.
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Simon, H., T. Wallmann und T. Mo¨nk. „Improvements in Performance Characteristics of Single-Stage and Multistage Centrifugal Compressors by Simultaneous Adjustments of Inlet Guide Vanes and Diffuser Vanes“. Journal of Turbomachinery 109, Nr. 1 (01.01.1987): 41–47. http://dx.doi.org/10.1115/1.3262068.
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Nowadays, multistage geared centrifugal compressors are most often equipped with three-dimensional impellers and adjustable inlet guide vane cascades, at least upstream of the first stage. Optimum stage efficiencies are made possible by optimum axial in-flow into each stage and freely selectable pinion shaft speeds. Combined with intercooling of the medium, the result is high machine efficiency with good operating ranges. Additional increases in efficiency can be achieved by means of vaned diffusers. Due to the attendant restriction to the working range, this solution is not common in production compressors. Nevertheless, the working range can be distinctly expanded by adjusting the diffuser vanes. In addition, the combination of simultaneous adjustment to inlet guide vanes and diffuser vanes enables an increase in machine efficiency over the entire operating range as compared with regulation using only inlet guide vanes or diffuser vanes. This paper reports on the development of centrifugal compressor stages equipped with vaned diffusers. The impellers have backward-curved blades. Experimental determination of suitable schedules for simultaneous adjustment of both inlet guide vanes and diffuser vanes, depending on the desired performance characteristic, will be dealt with in detail. Furthermore, some examples of the overall performance maps for multistage inter-cooled geared compressors will be shown as a result of combining the performance characteristic curves of the individual stages. The operating ranges and regions of maximum efficiency are optimally matched to the requirements in question by means of suitable adjustment schedules.
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Suryono, Edy, und Agustinus Eko Budi Nusantara. „SIMULASI TURBIN CROSSFLOW DENGAN JUMLAH SUDU 18 SEBAGAI PEMBANGKIT LISTRIK PICOHYDRO“. Simetris : Jurnal Teknik Mesin, Elektro dan Ilmu Komputer 8, Nr. 2 (01.11.2017): 547. http://dx.doi.org/10.24176/simet.v8i2.1412.
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ABSTRAK Dewasa ini isu krisis energi terus berkembang, dimana dibutuhkan energi terbarukan agar dapat menggantikan energi fosil yang menurut perkiraan akan segera habis, sehingga apabila tidak ada energi yang terbarukan maka manusia akan kekurangan energi. Salah satu upaya pengembangan energi terbarukan adalah dengan pengembangan pembangkit listri bertenaga air yang bernama picohydro, dimana picohydro ini dapat menghasilkan energi listrik kurang dari 5 kW. Hal ini terutama diaplikasikan untuk debit air yang rendah.Penelitian ini ditujukan untuk mensimulasikan turbin crossflow pada komponen pembangkit picohydro. Turbin berdiameter 13.5 cm, diameter shaft 3 cm, diameter inlet 4 cm dan jumlah sudu sebanyak 18 buah. Simulasi menggunakan software gambit dan CFD Fluent. Desain terdiri dari inlet, outlet, fluida rotate dan wall. Inlet diatur dengan kecepatan 6 m/s, turbulent intensity 5% dan hydraulic diameter 0,04 m. Fluida rotate diseting pada kondisi moving reference frame. Equisize skew mesh diatur dengan rentang nilai 0-1 dan aspect ratio mesh dari desain bernilai 1-3.Simulasi dari turbin crossflow dengan sudu 18 buah menghasilkan kecepatan rotasi sudu sebesar 16.5 rad/s atau angular velocity sebesar 157.5633 rpm, dan moment sebesar 290.39 Nm. Sehingga daya optimal yang dihasilkan adalah sebesar 4791 watt (4.791 kw). Kata kunci: picohydro, crossflow, CFD Fluent,
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Zhu, Di, Ran Tao, Ruofu Xiao, Wei Yang, Weichao Liu und Fujun Wang. „Optimization design of hydraulic performance in vaned mixed-flow pump“. Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 234, Nr. 7 (14.11.2019): 934–46. http://dx.doi.org/10.1177/0957650919887584.
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Vaned mixed-flow pump is widely used in industrial and agricultural cases. Considering mixed-flow impeller and space guide-vanes, the impeller and guide-vane blade angles need optimization design. In order to conduct optimization, the global dynamic-criterion algorithm with the ability of parallel running, dynamic criterion and escaping from local-best trap was used in this case. Based on numerical simulation and experimental verification, the 18 parameters' combination was optimized using this algorithm to achieve higher-efficiency in a specific flow rate range around the design condition. The numerical results showed that the weighted efficiency increased from 87.32% to 89.26% and the head coefficient decreased from 0.720 to 0.693. The improved efficiency and reduced head under design requirement helps to reduce the shaft power and energy consumption. The optimized blade inlet angle matches the inlet angle and improves the uniformity of flow in the impeller. The impeller outlet angle matches the guide vane inlet angle. Therefore, the flow regime becomes smoother in the rotor stator interaction region. The experimental results verify that the optimized pump efficiency was 85.75%. The measured head coefficient was 0.643 which meets the design requirement. This study provides a successful work for the green design of impeller and guide-vane of mixed-flow pump.
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Fatsis, Antonios. „Performance Enhancement of One and Two-Shaft Industrial Turboshaft Engines Topped With Wave Rotors“. International Journal of Turbo & Jet-Engines 35, Nr. 2 (25.05.2018): 137–47. http://dx.doi.org/10.1515/tjj-2016-0040.
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Abstract Wave rotors are rotating equipment designed to exchange energy between high and low enthalpy fluids by means of unsteady pressure waves. In turbomachinery, they can be used as topping devices to gas turbines aiming to improve performance. The integration of a wave rotor into a ground power unit is far more attractive than into an aeronautical application, since it is not accompanied by any inconvenience concerning the over-weight and extra dimensioning. Two are the most common types of ground industrial gas turbines: The one-shaft and the two-shaft engines. Cycle analysis for both types of gas turbine engines topped with a four-port wave rotor is calculated and their performance is compared to the performance of the baseline engine accordingly. It is concluded that important benefits are obtained in terms of specific work and specific fuel consumption, especially compared to baseline engines with low compressor pressure ratio and low turbine inlet temperature.
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Yu, Z., und D. W. Childs. „A Comparison of Experimental Rotordynamic Coefficients and Leakage Characteristics Between Hole-Pattern Gas Damper Seals and a Honeycomb Seal“. Journal of Engineering for Gas Turbines and Power 120, Nr. 4 (01.10.1998): 778–83. http://dx.doi.org/10.1115/1.2818467.
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Honeycomb annular seals are an attractive design alternative due to their superior static and dynamic performance. However, their implementation in industrial practice has been delayed by the following characteristics: a) manufacturing time can be appreciable, and b) they can seriously damage the shaft if rubbing occurs. To minimize these problems, “hole-pattern” gas damper seals, which are formed by simply drilling holes into an annular smooth seal, were manufactured and tested. The hole-pattern damper seal stator can be made of high-strength plastic materials which are less likely to damage a shaft during rubbing. The experimental results presented demonstrate that, compared to a honeycomb seal, a hole-pattern damper seal with 3.18 mm hole diameters and a high percentage of hole surface has achieved: (a) an average of 12 percent reduction in leakage rate, and(b) considerably higher effective damping, especially under high speeds and low inlet pressure ratio conditions.
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BORZEA, Claudia, Adrian SAVESCU, Iulian VLADUCA und Adrian STOICESCU. „ASYNCHRONOUS THREE-PHASE MACHINE DRIVEN AS GENERATOR BY A TWIN-SCREW EXPANDER“. "ACTUALITĂŢI ŞI PERSPECTIVE ÎN DOMENIUL MAŞINILOR ELECTRICE (ELECTRIC MACHINES, MATERIALS AND DRIVES - PRESENT AND TRENDS)" 2020, Nr. 1 (10.02.2021): 1–8. http://dx.doi.org/10.36801/apme.2020.1.5.
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The paper presents the functioning regimes of a 132 kW asynchronous three-phase machine, used for the expander-generator system in a compressed air energy storage facility. The installation consists of a 110 kW twin-screw electro-compressor, which supplies pressurized air up to ~16 bar into a 50 cubic meters storage vessel. The compressed air is afterwards released from the reservoir into expander’s inlet, spinning its shaft. When the expander’s shaft spins the electric machine over its synchronous speed, this one enters in generator mode, supplying electric power into the grid. Two power analysers installed on the automation control cabinet monitor the generated/absorbed power and the power supplied/consumed by the system from the grid. Using the data acquired by means of PLC during commissioning tests, we plotted the power curves, differential pressure and significant temperatures, as well as the electric machine’s speed.
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Prasetyo, Totok, Mochamad Denny Surindra, Wahyu Caesarendra, Taufik, Adam Glowacz, Muhammad Irfan und Witold Glowacz. „Influence of Superheated Vapour in Organic Rankine Cycles with Working Fluid R123 Utilizing Low-Temperature Geothermal Resources“. Symmetry 12, Nr. 9 (07.09.2020): 1463. http://dx.doi.org/10.3390/sym12091463.
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An organic Rankine cycle (ORC) system with R123 working fluid has been utilised for generating electricity from low-temperature geothermal resources. The degree of superheated vapour warrants attention to be studied further. This is because the degree of superheated vapour is the last point to absorb heat energy from geothermal heat sources and influence the amount of expansion power produced by the expander. Therefore, achieving high ORC system efficiency requires a parameter of superheated vapour degree. This paper presents an experimental study on a binary cycle, applying R123 as the working fluid, to investigate the effect of variation in superheated vapour degree on the ORC efficiency. Geothermal heat sources were simulated with conduction oil as an external heat source to provide input heat to the ORC system. The temperature high inlet (TH in) evaporator was designed to remain at 120 °C during the experiment, while mass flow rate was adjusted to make superheated vapour variations, namely set at 278, 280, 282, 284, and 286 K. Furthermore, the effect was observed on heat transfer inlet, pinch, heat transfer coefficient, expander work output, isentropic efficiency, expander shaft power, power generation, thermal efficiency, and ORC efficiency. The experimental results showed that the mass flow rate nearly remained unchanged at different degrees of superheated vapour. The ranges of heat transfer inlet, pinch temperature, and heat transfer coefficient were 25.34–27.89 kJ/kg, 9.35–4.08 °C, 200.62–232.54 W/m2·K, respectively. In conclusion, ORC system efficiency can be triggered by various parameters, including the temperature on the exit side of the evaporator. The superheated vapour of R123 working fluid to higher temperatures has caused a decrease in ORC system efficiency due to the decrease in heat transfer inlets, although theoretically, the work total increased. Further investigation has found that the magnitude of the mass flow rate affects the behaviour of the components of the ORC system.
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Antolín-Urbaneja, J. C., J. Lasa, P. Estensoro, I. Cabanes und M. Marcos. „Innovative Hydraulic Power Take-Off Construction and Performance Tests for Wave Energy Conversion“. Applied Mechanics and Materials 432 (September 2013): 316–23. http://dx.doi.org/10.4028/www.scientific.net/amm.432.316.
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This document describes and demonstrates the features of a new innovative hydraulic Power take-Off (PTO) to be used for Wave Energy Conversion. This device is able to transform low frequency oscillating movement into a continuous high frequency angular speed, absorbing high fluctuated torque at the input shaft, which can reach up to 8000Nm. Moreover, the major breakthrough of this device is that it can control the braking torque through the modification of some geometrical parameters, L and R, and through the activation of more than one hydraulic cylinder together with the pressure. The output shaft of the PTO is able to rotate at different continuous rated speed through the actuation on a specific control valve at the inlet of the hydraulic motor. Tests to check the behavior of the PTO related to the smoothening of the power output and concerning the time needed to increase the high pressure and the time available after the accumulation of some quantity of energy in different initial conditions are presented.
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Arifin, Maulana. „Rotordynamics analysis of solar hybrid microturbine for concentrated solar power“. Journal of Mechatronics, Electrical Power, and Vehicular Technology 11, Nr. 1 (30.07.2020): 38. http://dx.doi.org/10.14203/j.mev.2020.v11.38-44.
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Microturbine based on a parabolic dish solar concentrator runs at high speed and has large amplitudes of subsynchronous turbo-shaft motion due to the direct normal irradiance (DNI) fluctuation in daily operation. A detailed rotordynamics model coupled to a full fluid film radial or journal bearing model needs to be addressed for increasing performance and to ensure safe operating conditions. The present paper delivers predictions of rotor tip displacement in the microturbine rotor assembly supported by a journal bearing under non-linear vibrations. The rotor assembly operates at 72 krpm on the design speed and delivers a 40 kW power output with the turbine inlet temperature is about 950 °C. The turbo-shaft oil temperature range is between 50 °C to 90 °C. The vibrations on the tip radial compressor and turbine were presented and evaluated in the commercial software GT-Suite environment. The microturbine rotors assembly model shows good results in predicting maximum tip displacement at the rotors with respect to the frequency and time domain.
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Hu, Peixin, und Mehrdad Zangeneh. „Investigations of 3D Turbulent Flow Inside and Around a Water-Jet Intake Duct Under Different Operating Conditions“. Journal of Fluids Engineering 121, Nr. 2 (01.06.1999): 396–404. http://dx.doi.org/10.1115/1.2822221.
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In this paper the flow field in the intake duct of a model water-jet unit is studied by using a commercial 3D CFD code. In order to model the intake duct/hull interaction, the computational domain includes a large section of the hull in the vicinity of the intake duct opening. Appropriate boundary conditions are used on the far upstream and downstream of the duct inlet in order to minimize the effect of the domain boundaries on the flow field in the vicinity of the intake duct. Computations are performed for different boat speeds and flowrates. In addition, the effects of the impeller shaft, shaft rotation, boat trim as well as the traverse flow across the hull are investigated. The results of the computations are compared with some preliminary experimental results obtained from model self-propulsion tests in a towing tank. Good correlation is obtained between the predictions and the experimental results.
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Gao, Xiongfa, Ting Zhao, Weidong Shi, Desheng Zhang, Ya Shi, Ling Zhou und Hao Chang. „Numerical Investigation of an Open-Design Vortex Pump with Different Blade Wrap Angles of Impeller“. Processes 8, Nr. 12 (04.12.2020): 1601. http://dx.doi.org/10.3390/pr8121601.
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The blade wrap angle of impeller is an important structural parameter in the hydraulic design of open-design vortex pump. In this paper, taking a vortex pump with a cylindrical blade structure as the research object, two kinds of different blade wrap angle of vortex pump impellers are designed. The experiment and numerical simulation research is carried out, and the results of external characteristics and internal flow field are obtained under different flow rate. The results show that when ensuring that other main structural parameters remain unchanged, the efficiency and head of open-design vortex pump increase with the blade wrap angle decreases. In the case of blade wrap angle increasing, the length of rotating reflux back from lateral cavity to inlet is longer. For the same type of vortex pump, the length of rotating reflux to inlet decreases with the increase of flow rate. At the inlet area of impeller front face, there is an area where liquid flows back to the lateral cavity. The volute section shows that after passing through the impeller and lateral cavity, the liquid is discharged to the pump outlet with strong spiral strength. It is found that the blade wrap angle decreases and the shaft power increases, while the pump efficiency increases. The impeller blade wrap angle of vortex pump can be considered to select a smaller value.
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Sukhotski, A. B., G. S. Marshalova und Е. S. Danil’chik. „Specific Features of Calculating the Radiant Component of the Heat Flow of Horizontal Bunch from Finned Tubes with Exhaust Shaft“. ENERGETIKA. Proceedings of CIS higher education institutions and power engineering associations 63, Nr. 4 (07.08.2020): 380–88. http://dx.doi.org/10.21122/1029-7448-2020-63-4-380-388.
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The article discusses the heat exchange of radiation of bunches of round finned tubes with the environment and the exhaust shaft. The system of equations describing the entire set of primary processes that make up the radiation heat exchange of finned bundles is very complex mathematically; therefore, the calculations of radiant heat transfer are usually based on a number of simplifying assumptions with a involuntarily distortion of the real physical picture. The main methods for calculating radiation used in engineering practice, viz. calculation by the average angular coefficient and the zonal method are briefly considered. A refined zonal method for calculating the radiant component of the heat flow of a horizontal bunch of finned tubes with an exhaust shaft is proposed. An experimental study of single-row bunches of finned tubes with different annular steps S1 (64 and 70 mm) was carried out for small Reynolds numbers Re = 130–720 in a wide range of the determining temperature at the beam inlet (16–83 °C). The aluminum finning of the bunch tube had the following parameters: screw finning diameter d = 0.0568 m; diameter of the tube at the base d0 = 0.0264 m; height, step and average fin thickness, respectively, h = 0.0152 m, s = 0.00243 m and Δ = 0.00055 m. Air movement in the bunch was carried out by gravitational traction created by a rectangular exhaust shaft. The experimental bunch was installed above the shaft, and the air was preheated before entering the shaft, which allowed expanding the temperature range of the air at the entrance to the bunch. It was found that incorrect accounting for a bunch reemission with an exhaust shaft when calculating single-row finned bunches causes a decrease in convective heat transfer by 7–25 %.
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Gruver, J. K., R. D. Flack und K. Brun. „Laser Velocimeter Measurements in the Pump of an Automotive Torque Converter: Part I—Average Measurements“. Journal of Turbomachinery 118, Nr. 3 (01.07.1996): 562–69. http://dx.doi.org/10.1115/1.2836703.
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A torque converter was tested for two turbine/pump rotational speed ratios, 0.065 and 0.800, and a laser velocimeter was used to measure three components of velocity within the pump. Shaft encoders were used to record the instantaneous pump angular position, which was correlated with the velocities. Average flow velocity profiles were obtained for the pump inlet, mid-, and exit planes. Large separation regions were seen in the mid- and exit planes of the pump for a speed ratio of 0.800. Strong counterclockwise secondary flows were observed in the midplane and strong clockwise secondary flows were seen in the exit plane of the pump for all conditions; vorticities were evaluated and are reported. Velocity data were also used to find the torque distribution. For both speed ratios the torque was approximately evenly distributed between the inlet and exit. Finally, slip factors were evaluated at the mid-and exit planes. At the midplane they were approximately the same as for conventional centrifugal pumps; however, at the exit plane the slip factors are larger than for centrifugal pumps.