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1
Wadia, A. R., P. N. Szucs e K. L. Gundy-Burlet. "Design and Testing of Swept and Leaned Outlet Guide Vanes to Reduce Stator–Strut–Splitter Aerodynamic Flow Interactions". Journal of Turbomachinery 121, n. 3 (1 luglio 1999): 416–27. http://dx.doi.org/10.1115/1.2841334.
Testo completoAbstract (sommario):
Large circumferentially varying pressure levels produced by aerodynamic flow interactions between downstream stators and struts present a potential noise and stability margin liability in a compression component. These interactions are presently controlled by tailoring the camber and/or stagger angles of vanes neighboring the fan frame struts. This paper reports on the design and testing of a unique set of swept and leaned fan outlet guide vanes (OGVs) that do not require this local tailoring even though the OGVs are closely coupled with the fan frame struts and splitter to reduce engine length. The swept and leaned OGVs not only reduce core-duct diffusion, but they also reduce the potential flow interaction between the stator and the strut relative to that produced by conventional radial OGVs. First, the design of the outlet guide vanes using a single blade row three-dimensional viscous flow analysis is outlined. Next, a two-dimensional potential flow analysis was used for the coupled OGV–frame system to obtain a circumferentially nonuniform stator stagger angle distribution to reduce the upstream static pressure disturbance further. Recognizing the limitations of the two-dimensional potential flow analysis for this highly three-dimensional set of leaned OGVs, as a final evaluation of the OGV–strut system design, a full three-dimensional viscous analysis of a periodic circumferential sector of the OGVs, including the fan frame struts and splitter, was performed. The computer model was derived from a NASA-developed code used in simulating the flow field for external aerodynamic applications with complex geometries. The three-dimensional coupled OGV–frame analysis included the uniformly staggered OGV configuration and the variably staggered OGV configuration determined by the two-dimensional potential flow analysis. Contrary to the two-dimensional calculations, the three-dimensional analysis revealed significant flow problems with the variably staggered OGV configuration and showed less upstream flow nonuniformity with the uniformly staggered OGV configuration. The flow redistribution in both the radial and tangential directions, captured fully only in the three-dimensional analysis, was identified as the prime contributor to the lower flow nonuniformity with the uniformly staggered OGV configuration. The coupled three-dimensional analysis was also used to validate the design at off-design conditions. Engine test performance and stability measurements with both uniformly and variably staggered OGV configurations with and without the presence of inlet distortion confirmed the conclusions from the three-dimensional analysis.
2
Jonsson, Isak, Valery Chernoray e Radheesh Dhanasegaran. "Infrared Thermography Investigation of Heat Transfer on Outlet Guide Vanes in a Turbine Rear Structure". International Journal of Turbomachinery, Propulsion and Power 5, n. 3 (1 settembre 2020): 23. http://dx.doi.org/10.3390/ijtpp5030023.
Testo completoAbstract (sommario):
Aerothermal heat transfer measurements in fluid dynamics have a relatively high acceptance of uncertainty due to the intricate nature of the experiments. The large velocity and pressure gradients present in turbomachinery application add further complexity to the measurement procedure. Recent method and manufacturing development has addressed some of the primary sources of uncertainty in these heat transfer measurements. However, new methods have so far not been applied in a holistic approach for heat transfer studies. This gap is bridged in the present study where a cost-effective and highly accurate method for heat transfer measurements is implemented, utilising infrared thermography technique (IRT) for surface temperature measurement. Novel heat transfer results are obtained for the turbine rear sturcture (TRS), at engine representative conditions for three different outlet guide vane (OGV) blade loading and at Reynolds Number of 235000. In addition to that, an extensive description of the implementation and error mitigation is presented.
3
Mårtensson, Hans. "Harmonic Forcing from Distortion in a Boundary Layer Ingesting Fan". Aerospace 8, n. 3 (24 febbraio 2021): 58. http://dx.doi.org/10.3390/aerospace8030058.
Testo completoAbstract (sommario):
Integrating a fan with a boundary layer ingestion (BLI) configuration into an aircraft fuselage can improve propulsion efficiency by utilizing the lower momentum airflow in the boundary layer developed due to the surface drag of the fuselage. As a consequence, velocity and total pressure variations distort the flow field entering the fan in both the circumferential and radial directions. Such variations can negatively affect fan aerodynamics and give rise to vibration issues. A fan configuration to benefit from BLI needs to allow for distortion without large penalties. Full annulus unsteady computational fluid dynamics (CFD) with all blades and vanes is used to evaluate the effects on aerodynamic loading and forcing on a fan designed to be mounted on an adapted rear fuselage of a Fokker 100 aircraft, i.e., a tail cone thruster. The distortion pattern used as a boundary condition on the fan is taken from a CFD analysis of the whole aircraft with a simplified model of the installed fan. Detailed simulations of the fan are conducted to better understand the relation between ingested distortion and the harmonic forcing. The results suggest that the normalized harmonic forcing spectrum is primarily correlated to the circumferential variation of inlet total pressure. In this study, the evaluated harmonic forces correlate with the total pressure variation at the inlet for the first 12 engine orders, with some exceptions where the response is very low. At higher harmonics, the distortion content as well as the response become very low, with amplitudes in the order of magnitude lower than the principal disturbances. The change in harmonic forcing resulting from raising the working line, thus, increasing the incidence on the fan rotor, increases the forcing moderately. The distortion transfers through the fan resulting in a non-axisymmetric aerodynamic loading of the outlet guide vane (OGV) that has a clear effect on the aerodynamics. The time average aerodynamic load and also the harmonic forcing of the OGV vary strongly around the circumference. In particular, this is the case for some of the vanes at higher back pressure, most likely due to an interaction with separations starting to occur on vanes operating in unfavorable conditions.
4
Barker, A. G., e J. F. Carrotte. "Compressor Exit Conditions and Their Impact on Flame Tube Injector Flows". Journal of Engineering for Gas Turbines and Power 124, n. 1 (1 marzo 1999): 10–19. http://dx.doi.org/10.1115/1.1383773.
Testo completoAbstract (sommario):
Within a gas turbine engine the flow field issuing from the compression system is nonuniform containing, for example, circumferential and radial variations in the flow field due to wakes from the upstream compressor outlet guide vanes (OGVs). In addition, variations can arise due to the presence of radial load bearing struts within the pre-diffuser. This paper is concerned with the characterization of this nonuniform flow field, prior to the combustion system, and the subsequent effect on the flame tube fuel injector flows and hence combustion processes. A mainly experimental investigation has been undertaken using a fully annular test facility which incorporates a single stage axial flow compressor, diffuser, and flame tube. Measurements have been made of the flow field, and its frequency content, within the dump cavity. Furthermore, the stagnation pressure presented to the core, outer and dome swirler passages of a fuel injector has been obtained for different circumferential positions of the upstream OGV/pre-diffuser assembly. These pressure variations, amounting to as much as 20 percent of the pressure drop across the fuel injector, also affect the flow field immediately downstream of the injector. In addition, general variations in pressure around the fuel injector have also been observed due to, for example, the fuel injector position relative to pre-diffuser exit and the flame tube cowl.
5
Luo, Lei, Chenglong Wang, Lei Wang, Bengt Sundén e Songtao Wang. "Endwall heat transfer and aerodynamic performance of bowed outlet guide vanes (OGVs) with on- and off-design conditions". Numerical Heat Transfer, Part A: Applications 69, n. 4 (30 novembre 2015): 352–68. http://dx.doi.org/10.1080/10407782.2015.1081021.
Testo completo
6
Chikere, Aja O., Hussain H. Al-Kayiem e Zainal Ambri A. Karim. "Thermal Diffusion Performance of a Diffuser by various Guide Vanes configurations". MATEC Web of Conferences 225 (2018): 03018. http://dx.doi.org/10.1051/matecconf/201822503018.
Testo completoAbstract (sommario):
The use of vane-less diffuser with large diffusion angle has shown a setback in the diffusion process of high temperature working fluids. The hot gas flow was characterized as a jet-like flow. This paper presents problem, encountered practically, using a vane-less diffuser with large diffusion angle and how the problem is solved by CFD simulation. The investigated thermal diffuser has a length of 0.3 m, an inlet to outlet crosssectional area ratio of 1:25 and diffusion angle of 115.44o. To resolve the jet-like flow problem and poor distribution of the flow temperature at the diffuser outlet, the study suggested the use of guide-vanes into the diffuser. The study employed CFD simulation by ANSYS-FLUENT software to analyze the flow and thermal process in the diffuser. Three different shapes of guide vanes; block-shaped, oval-shaped and airfoil-shaped were considered in this study and at different vanes diffusion angles, as well as vane-less case, which was adopted as the bench mark case. The simulation results of the velocity, temperature and pressure at the diffuser outlet were compared for all cases. It was found that the guide vanes with symmetrical airfoil profile provided the best performance with most uniform distribution at the outlet of the diffuser. Also, the airfoil-shaped guide vanes resulted in lower pressure losses compared to the block-shaped and oval-shaped guide vanes. According to the analysis results, the diffuser was redesigned to improve the diffusion and temperature distribution across the diffuser outlet.
7
Carrotte, J. F., K. F. Young e S. J. Stevens. "Measurements of the Flow Field Within a Compressor Outlet Guide Vane Passage". Journal of Turbomachinery 117, n. 1 (1 gennaio 1995): 29–37. http://dx.doi.org/10.1115/1.2835641.
Testo completoAbstract (sommario):
A series of tests have been carried out to investigate the flow in a Compressor Outlet Guide Vane (OGV) blade row downstream of a single-stage rotor. The subsequent flow field that developed within an OGV passage was measured, at intervals of 10 percent axial chord, using a novel design of miniature five-hole pressure probe. In addition to indicating overall pressure levels and the growth of regions containing low-energy fluid, secondary flow features were identified from calculated axial vorticity contours and flow vectors. Close to each casing the development of classical secondary flow was observed, but toward the center of the annulus large well-defined regions of opposite rotation were measured. These latter flows were due to the streamwise vorticity at inlet to the blade row associated with the skewed inlet profile. Surface static pressures were also measured and used to obtain the blade pressure force at three spanwise locations. These values were compared with the local changes in flow momentum calculated from the measured velocity distributions. With the exception of the flow close to the outer casing, which is affected by rotor tip leakage, good agreement was found between these quantities indicating relatively weak radial mixing.
8
Zhu, Honggeng, e Rentian Zhang. "Numerical Simulation of Internal Flow and Performance Prediction of Tubular Pump with Adjustable Guide Vanes". Advances in Mechanical Engineering 6 (1 gennaio 2014): 171504. http://dx.doi.org/10.1155/2014/171504.
Testo completoAbstract (sommario):
Aiming at the performance defect of tubular pump with fixed guide vanes, a design scheme of tubular pump with adjustable guide vanes is proposed, so that the inlet setting angle of guide vanes can be flexibly adjusted to coordinate with the operation conditions of pump, to ensure the inlet setting angle of guide vanes changing with the outlet flow angle of the impeller. The three-dimensional time-averaged incompressible Navier-Stokes equations are adopted to numerically simulate the internal flow field of a tubular pump with fixed and adjustable guide vanes, respectively. Computed results indicate that with the design of adjustable guide vanes and at off-design flow rates the flow conditions inside the diffuser of tubular pump can be improved effectively, and its hydraulic losses can be reduced. When the impeller blade angles are fixed the best efficiency points are within 0.51% while adjusting setting angles of guide vanes within a certain range. Under off-design conditions the hydraulic efficiency of tubular pump with adjustable guide vanes can be obviously improved by 1.70% at 0.75 Q0 and 2.19% at 1.20 Q0, when the blade angle is 0 degrees and the angle of guide vanes is adjusted to be 2 degrees smaller and larger, respectively.
9
Han, Fenghui, Zhe Wang, Yijun Mao, Jiajian Tan e Wenhua Li. "Experimental and numerical studies on the influence of inlet guide vanes of centrifugal compressor on the flow field characteristics of inlet chamber". Advances in Mechanical Engineering 12, n. 11 (novembre 2020): 168781402097490. http://dx.doi.org/10.1177/1687814020974909.
Testo completoAbstract (sommario):
Inlet chambers (IC) are the typical upstream component of centrifugal compressors, and inlet guide vanes in the IC have a great impact on its internal flow and aerodynamic loss, which will significantly influence the performance of the downstream compressor stages. In this paper, an experimental study was carried out on the flow characteristics inside a radial IC of an industrial centrifugal compressor, including five testing sections and 968 measuring points for two schemes with and without guide vanes. Detailed distributions of flow parameters on each section were obtained as well as the overall performance of the radial IC, and the causes of the flow loss inside the IC and the non-uniformity of flow parameters at the outlet section were investigated. Besides, numerical simulations were performed to further analyze the flow characteristics inside the radial IC. The experimental and numerical results indicate that, in the scheme without guide vanes, sudden expansions in the spiral channel and flow separations in the annular convergence channel are the major sources of flow loss and distortions generated in the radial IC; while in the scheme with guide vanes, the flow impacts, separations and wakes caused by the inappropriate design of guide vanes are the main reasons for the flow loss of the IC itself and the uneven flow distributions at the IC outlet.
10
Harris, Jonah, Bharat Lad e Sina Stapelfeldt. "Two-Dimensional Investigation of the Fundamentals of OGV Buffeting". International Journal of Turbomachinery, Propulsion and Power 7, n. 2 (2 aprile 2022): 13. http://dx.doi.org/10.3390/ijtpp7020013.
Testo completoAbstract (sommario):
The increased demands of compact modern aero engine architectures have highlighted the problem of outlet guide vane (OGV) buffeting in off-design conditions. This structural response to aerodynamic excitations is characterised by increased vibration, risking structural fatigue. Investigations focused on understanding, mitigation and avoidance are therefore of high priority. OGV buffet is a type of transonic buffet caused by unsteady shock movement, but the exact parameters driving it are not fully understood. To try and understand them, this paper examines the buffet of a quasi-2D OGV geometry. Parametric studies of the incidence angle and inlet Mach number were performed. Forcing frequencies for both studies were found to be close to the experimentally detected frequency of vibration in the first bow mode, which demonstrates that buffet is driven by quasi-2D flow features. Increasing the inlet Mach number increased the dominant forcing frequency, whereas increasing the incidence yielded little change. Profiles of unsteady pressure amplitudes were shown to smoothly increase in magnitude with an increasing incidence and inlet Mach number.
11
Zhang, Huiyan, Fan Meng, Lei Cao, Yanjun Li e Xinkun Wang. "The Influence of a Pumping Chamber on Hydraulic Losses in a Mixed-Flow Pump". Processes 10, n. 2 (19 febbraio 2022): 407. http://dx.doi.org/10.3390/pr10020407.
Testo completoAbstract (sommario):
In this study, entropy generation theory based on computational fluid dynamics (CFD) is used to study the influence of a pumping chamber type (guide vane and volute scheme) on the spatial distribution of hydraulic loss in a mixed-flow pump. The CFD data of the mixed-flow pump with a volute is validated by external characteristic test data under Q = 561.4–1598.6 m3/h. The results show that the efficiency and the head of the guide vanes scheme are lower under Q = 800–1200 m3/h, which resulted from a higher total entropy production (TEP) in the pumping chamber and outlet pipe. The high total entropy production rate (TEPR) inside the guide vanes can be found near the leading edge of the hub side and trailing edge of the rim side due to flow separation, which reduces the recovery efficiency of kinetic energy of the guide vanes. The high TEPR inside outlet pipe can be seen near the inlet, caused by back flow. However, the efficiency and head of the volute scheme are lower, under Q = 1200–1600 m3/h, owing to the fact that the volute cannot effectively convert kinetic energy into pressure energy and thus the high TEPR can be found near outlet of volute and inlet of outlet pipe. These results can provide useful suggestions to the matching optimization of the impeller and pumping chamber in a mixed-flow pump.
12
Lei, Zhijun, Hanliu Deng, Xiaoqing Ouyang, Yanfeng Zhang, Xingen Lu, Gang Xu e Junqiang Zhu. "Numerical Research on the Jet Mixing Mechanism of the De-Swirling Lobed Mixer Integrated with OGV". Energies 16, n. 11 (29 maggio 2023): 4394. http://dx.doi.org/10.3390/en16114394.
Testo completoAbstract (sommario):
The outlet guide vane (OGV) is integrated with the lobed mixer to improve the exhaust system’s performance with a high core inlet swirl. The best location for integrating the OGV is along the central line of the lobe’s trough and near the exit plane of the lobed mixer. Two types of lobed mixers (the scalloped reference lobed mixer and the scalloped de-swirling lobed mixer) integrating with/without OGVs, are numerically researched under eight inlet swirl conditions ranging from 0° to 35°. The simulation used the Reynolds-Averaged Navier-Stokes (RANS) method with Shear Stress Transport (SST) model based on an unstructured mesh of 30 million cells. The reserved outlet flow angle of the de-swirling lobed mixer is beneficial for enhancing the strength of downstream streamwise vortices and accelerating the jet mixing. After integrating with OGV: it can significantly suppress the leakage vortex between the lobe trough and the central body and the backflow downstream of the central body; on the other hand, it can further increase the strength and scale of streamwise vortices by expanding the radial range of inner secondary flow, thereby accelerating mixing and reducing total pressure loss & thrust loss. Under the design condition, the integrated de-swirling lobed mixer can increase thrust by 3.18% and reduce the mixing loss by 31.17% compared with the reference lobed mixer. Even under non-design conditions, the integrated de-swirling lobed mixer can still use upstream inlet swirl to enhance the streamwise vortices and accelerate the jet mixing within the conditions studied in this paper. The outlet jet uniformity of the integrated de-swirling lobed mixer is better than that of the integrated reference lobed mixer for the case with the same core inlet swirl. Compared with the latter, the former also has better tolerance to the attack angle, especially for the negative attack angle conditions. Under the condition with a core inlet swirl of 35°, the thrust loss of the integrated de-swirling lobed mixer is 2.15% lower than that of the integrated reference lobed mixer.
13
Huang, Ping, Yajing Xiao, Jinfeng Zhang, Haikun Cai e Haiqin Song. "The Influence of Flow Rates on Pressure Fluctuation in the Pump Mode of Pump-Turbine with Splitter Blades". Applied Sciences 10, n. 19 (26 settembre 2020): 6752. http://dx.doi.org/10.3390/app10196752.
Testo completoAbstract (sommario):
This paper takes a pump-turbine as the research subject and, based on the Computational Fluid Dynamics (CFD) numerical method and combined with test data, investigates the pressure fluctuation characteristics in the pump mode and analyzes the pressure fluctuation characteristics at 0.75 Qd, 1.0 Qd and 1.25 Qd when the guide vane opening is 17.5°. The results showed that the protruding frequencies of pressure fluctuation in the bladeless region were mainly 5 fn, 10 fn and 20 fn, and the main frequencies in the runner area and near the outlet wall of the draft tube were 16 fn and 5 fn, respectively. At different heights for the guide vanes, the pressure fluctuation in the bladeless region had significant differences, and the pressure fluctuation near the bottom ring was the most intense. The amplitude of the rotor–stator interaction frequency continuously attenuates from the bladeless region to the outlet of the stay vanes, and the amplitude attenuation of each frequency is mainly concentrated in the area of the guide vanes. In this paper, the influence of different flow rates on the pressure fluctuation in the pump mode is analyzed, which provides a theoretical reference for the stability and further study of pump-turbines.
14
Ji, Dongtao, Weigang Lu, Bo Xu, Lei Xu e Tao Jiang. "Study on the Energy Loss Characteristics of Shaft Tubular Pump Device under Stall Conditions Based on the Entropy Production Method". Journal of Marine Science and Engineering 11, n. 8 (29 luglio 2023): 1512. http://dx.doi.org/10.3390/jmse11081512.
Testo completoAbstract (sommario):
This study aimed to reveal the energy loss characteristics of each part of the shaft tubular pump device (STPD) under stall conditions. Numerical simulations were conducted by using the SST k-ω turbulence model with curvature correction, and the reliability of the simulation results was verified by a model test. The entropy production method was used to evaluate and visualize the energy loss. The results show that turbulent entropy production (TEP) is the main source of energy loss in each component of the STPD, and the TEP increases significantly with the deterioration of stall. The energy loss in the impeller is mainly concentrated near the shroud and hub, while in the guide vanes it is mainly concentrated near the shroud and suction surface of the blades. In addition, with the deterioration of stall, the energy loss in the inlet of the impeller and guide vanes increases significantly. Influenced by the backflow from the impeller, there is a significant amount of energy loss at the outlet segment of the inlet passage, and the location of the high-energy-loss region is consistent with the backflow region. Affected by the flow separation vortex at the tail of the guide vanes, the energy loss in the outlet passage is mainly concentrated at the inlet segment.
15
Al-Obaidi, Ahmed Ramadhan. "Influence of guide vanes on the flow fields and performance of axial pump under unsteady flow conditions: Numerical study". Journal of Mechanical Engineering and Sciences 14, n. 2 (16 giugno 2020): 6570–93. http://dx.doi.org/10.15282/jmes.14.2.2020.04.0516.
Testo completoAbstract (sommario):
Influence of different guide vanes on structural of flow field and axial pump performance under unsteady flow is carried out using numerical method. A three-dimensional axial flow pump model is numerically simulated using computational fluid dynamics (CFD) method with four number of impeller blades and 3, 4, 5 and 6 guide vanes depend on the SIMPLE code, standard turbulence k-ε model as well as sliding mesh method (SMM). The static, dynamic, total pressures, shear stress, velocity magnitude and turbulent kinetic energy are the important features which affecting instability operation in the pump. By monitoring above parameters and setting different measurement pressure points, the average pressures in the pump are discussed and the effect of guide vanes on the average pressure is analyzed. The results demonstrate that the numerical calculations can provide good accurately prediction for the characteristics of internal flow in the pump. The numerical results are closed to experimental results the minimum errors of pressure differences can reach 2.5% and the maximum errors 6.5%. The guide vanes have more effect on the flow field and pressure variations especially at outlet region in the axial pump. As compared with the using various guide vanes, the pressure increases as number of vanes increase that can lead the performance of pump also increases. Pressure differences in the pump at variety mass flow for vane 6 is higher than other vanes 3, 4 and 5 by 14.13, 11.35 and 3.85% for flow of 5 L/min. Further, the dynamic pressure differences for design flow between different vanes 6, 5, 4 and 3 are about by 2.87, 7.26 and 8.51% respectively.
16
Jiang, P. M., e A. Whitfield. "Investigation of Vaned Diffusers as a Variable Geometry Device for Application to Turbocharger Compressors". Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 206, n. 3 (luglio 1992): 209–20. http://dx.doi.org/10.1243/pime_proc_1992_206_179_02.
Testo completoAbstract (sommario):
The potential of guide vanes as a variable geometry device, placed in the conventional vaneless diffuser, to extend the operating range of a turbocharger compressor is investigated. Vaned diffusers are not normally employed in turbocharger applications as the consequent reduction in operating range is more damaging than the beneficial improvement in peak efficiency and pressure ratio. The variable geometry concept considered here is primarily one in which the guide vanes are introduced at the near surge flow conditions. The leading edge vane angle is set to accept the highly tangential flow at the near surge conditions, and the vane is then used to guide the fluid towards the radial direction in order to reduce the long flow path through the diffuser. Four types of vane arrangements are considered: (a) 12 and 6 full length vanes, with inlet vane angles of 75° and 80°; (b) 6 short inlet vanes to give a high aspect ratio; (c) 12 and 6 short vanes located in the outer half of the vaneless diffuser passage; and (d) double-row vane rings. It is shown that short vanes deployed at the diffuser outlet not only improve the efficiency and pressure ratio but also extend the high flow operating range. Further, the introduction of short inlet vanes with an inlet angle of 80° improves the peak pressure ratio and efficiency, and extends the near surge operating range.
17
Li, Wei, Mingjiang Liu, Leilei Ji, Yulu Wang, Muhammad Awais, Jingning Hu e Xiaoyan Ye. "Research on the Matching Characteristics of the Impellers and Guide Vanes of Seawater Desalination Pumps with High Capacity and Pressure". Journal of Marine Science and Engineering 10, n. 1 (15 gennaio 2022): 115. http://dx.doi.org/10.3390/jmse10010115.
Testo completoAbstract (sommario):
This paper presents the matching characteristics of impellers and guide vanes of high capacity and pressure seawater desalination pumps by using computational fluid dynamics (CFD). The single-stage pump is numerically calculated, and its external characteristics are consistent with the test results of model pump. Taking this scheme as a prototype, the research is carried out from three aspects: (i) the impeller blade outlet width; (ii) the number of impeller and guide vane blades; and (iii) the area ratio of impeller outlet to guide vane inlet. The results indicate that the blade outlet width significantly affects the pump head and efficiency. Appropriately increasing the number of guide vane blades or changing the number of impeller blades can improve efficiency and expand the high-efficiency area. Additionally, increasing the throat area of the guide vane has the opposite effect on the large flow and small flow area of the pump. An optimized hydraulic model design scheme is obtained.
18
Maatooq, Jaafar, e Zainab Zghaier. "Hydraulic performance of abrupt outlet transition structure with strip guide vanes at subcritical flow". MATEC Web of Conferences 162 (2018): 03009. http://dx.doi.org/10.1051/matecconf/201816203009.
Testo completoAbstract (sommario):
For some stream structures such as barrages, regulators, as well as change of channel cross section, the downstream expansion transitions structures are the common requirement. Eddies, as a result of the flow separation in such structures leads to destruction the bed and sides of the downstream channel. Head loss, on the other hand, produced through the expansion is important because it affects the stage at downstream. This study is restricted to developing the hydraulic performance of abrupt outlet transition at subcritical flow for both decreasing the head losses besides spreading the flow transversely to achieve regular velocity across the width as much as possible. New appurtenances, is adopting to install at specified configuration into a sudden transition. The appurtenances consisted of two successive rows of thin plates used as guide vanes to direct and spread the flow across the width with more uniformity. The guide vanes also keep the head losses at minimum possible. This attempt, through the results, proved that it has considerable hydraulic and economic advantages as compared to using a flared wall. Greater uniformity in velocity distributions of flow across the width, shorter length, and 70% lesser head loss are the results of the hydraulic performance of abrupt expansion transition equipped with two sets of strip vanes as compared to that with the plain one.
19
Yang, Fan, Hao-ru Zhao e Chao Liu. "Improvement of the Efficiency of the Axial-Flow Pump at Part Loads due to Installing Outlet Guide Vanes Mechanism". Mathematical Problems in Engineering 2016 (4 febbraio 2016): 1–10. http://dx.doi.org/10.1155/2016/6375314.
Testo completoAbstract (sommario):
In order to investigate the influence of adjustable outlet guide vane on the hydraulic performance of axial-flow pump at part loads, the axial-flow pump with 7 different outlet guide vane adjustable angles was simulated based on the RNG k-ε turbulent model and Reynolds time-averaged equations. The Vector graphs of airfoil flow were analyzed in the different operating conditions for different adjustable angles of guide vane. BP-ANN prediction model was established about the effect of adjustable outlet guide vane on the hydraulic performance of axial-flow pump based on the numerical results. The effectiveness of prediction model was verified by theoretical analysis and numerical simulation. The results show that, with the adjustable angle of guide vane increasing along clockwise, the high efficiency area moves to the large flow rate direction; otherwise, that moves to the small flow rate direction. The internal flow field of guide vane is improved by adjusting angle, and the flow separation of tail and guide vane inlet ledge are decreased or eliminated, so that the hydraulic efficiency of pumping system will be improved. The prediction accuracy of BP-ANN model is 1%, which can meet the requirement of practical engineering.
20
Meng, Fan, Yanjun Li, Jia Chen, Lei Xu e Yalin Li. "The Effect of Airfoil Camber on Pressure Fluctuation in Bidirectional Axial-Flow Pump". Processes 10, n. 3 (25 febbraio 2022): 468. http://dx.doi.org/10.3390/pr10030468.
Testo completoAbstract (sommario):
To obtain the influence of airfoil camber on the internal pressure fluctuation of a bidirectional axial-flow pump, the unsteady Reynolds time-averaged Navier–Stokes (URANS) equation was solved to predict the internal flow structure under three airfoil camber cases. The airfoil camber was quantitatively controlled by airfoil camber angle. The pressure standard deviation was used to define the local pressure fluctuation intensity (PFI) inside the impeller and guide vane. Fast Fourier transform was applied to analyze the frequency-domain characteristics of the pressure signal near the impeller–straight pipe interface and impeller–guide vanes interface. The results were validated by the external characteristic test. Under the forward condition, the area of high PFI near the outlet and leading edge of the impeller increased with a decrease in airfoil camber angle, and that near the leading edge of the guide vanes shifted to the middle section with a decrease in airfoil camber angle. The main frequency of the pressure signal near the impeller–guide vanes interface was the blade-passing frequency (BPF), and the main frequency amplitude increased with a decrease in airfoil camber angle. Under the reverse condition, the high PFI area near the inlet and the leading edge of the impeller declined with the decrease in airfoil camber angle. The main frequency of the pressure signal near the impeller–straight pipe interface and impeller–guide vanes interface was the BPF, and the main frequency amplitude decreased with a decrease in airfoil camber angle.
21
Horlock, J. H. "The Use of Circumferentially Varying Stagger Guide Vanes in an Axial Flow Pump or Compressor". Journal of Turbomachinery 112, n. 2 (1 aprile 1990): 294–97. http://dx.doi.org/10.1115/1.2927652.
Testo completoAbstract (sommario):
An actuator disk analysis is given of the flow through a guide vane and rotor combination. It is shown that changes in total pressure across the rotor are in general related to circumferential variations in guide vane outlet angle. In particular known variations in inlet total pressure may be eliminated by suitable circumferential changes in guide vane stagger.
22
Witte, Hauke, Christoph Bode e Jens Friedrichs. "Potential of Static Pressure Recovery of Rotor-Only Low-Pressure Axial Fans". International Journal of Turbomachinery, Propulsion and Power 8, n. 3 (8 settembre 2023): 33. http://dx.doi.org/10.3390/ijtpp8030033.
Testo completoAbstract (sommario):
Typically installed in a rotor-only configuration, low-pressure axial fans discharge directly into a free atmosphere and the discharge shows a strong swirl component. Since such designs, without guide vanes, cannot convert the dynamic pressure in the swirl component back into static pressure, the dynamic pressure is usually considered a loss. However, the radial equilibrium shows that a significant part of the kinetic energy contained in this swirl component is recovered as static pressure in the free atmosphere. This additional pressure increase has been sparsely researched. A comparison between two configurations with and without outlet guide vanes allows for the formulation of an evaluation criterion of the rotor-only configuration. Utilizing this evaluation criterion, the investigation of velocity profiles corresponding to generic rotor designs shows promise in terms of pressure recovery for new designs.
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Posson, Hélène, e Stéphane Moreau. "Effect of Rotor Shielding on Fan-Outlet Guide Vanes Broadband Noise Prediction". AIAA Journal 51, n. 7 (luglio 2013): 1576–92. http://dx.doi.org/10.2514/1.j051784.
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Sonoda, Toyotaka, e Heinz-Adolf Schreiber. "Aerodynamic Characteristics of Supercritical Outlet Guide Vanes at Low Reynolds Number Conditions". Journal of Turbomachinery 129, n. 4 (19 agosto 2006): 694–704. http://dx.doi.org/10.1115/1.2720868.
Testo completoAbstract (sommario):
As a part of an innovative aerodynamic design concept for a single stage low pressure turbine, a high turning outlet guide vane is required to remove the swirl from the hot gas. The airfoil of the vane is a highly loaded compressor airfoil that has to operate at very low Reynolds numbers (Re∼120,000). Recently published numerical design studies and experimental analysis on alternatively designed airfoils showed that blade profiles with an extreme front loaded pressure distribution are advantageous for low Reynolds number conditions. The advantage even holds true for an increased inlet Mach number at which the peak Mach number on the airfoils reaches and exceeds the critical conditions (Mss>1.0). This paper discusses the effect of the inlet Mach number and Reynolds number on the cascade performance for both a controlled diffusion airfoil (CDA) (called baseline) and a numerically optimized front loaded airfoil. The results show that it is advantageous to design the profile with a fairly steep pressure gradient immediately at the front part in order to promote early transition or to prevent too large laminar—even shock induced—separations with the risk of a bubble burst. Profile Mach number distributions and wake traverse data are presented for design and off-design conditions. The discussion of Mach number distributions and boundary layer behavior is supported by numerical results obtained from the blade-to-blade flow solver MISES.
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Ye, Changliang, Dongsen An, Wanru Huang, Yaguang Heng e Yuan Zheng. "Investigation on Stall Characteristics of Centrifugal Pump with Guide Vanes". Water 15, n. 1 (21 dicembre 2022): 21. http://dx.doi.org/10.3390/w15010021.
Testo completoAbstract (sommario):
Stall usually occurs in the hump area of the head curve, which will block the channel and aggravate the pump vibration. For centrifugal pumps with guide vanes usually have a clocking effect, the stall characteristic at different clocking positions should be focused. In this paper, the flow field of the centrifugal pump under stall conditions is numerically simulated, and the rotor–stator interaction effects of the centrifugal pump under stall conditions are studied. The double-hump characteristic is found in the head curve by using SAS (Scale Adaptive Simulation) model. The hump area close to the optimal working condition is caused by hydraulic loss, while the hump area far away from the optimal working condition point is caused by the combined action of Euler’s head and hydraulic loss. The SAS model can accurately calculate the wall friction loss, thus predicting the double-hump phenomenon. The pressure fluctuation and head characteristics at different clocking positions under stall conditions are obtained. It is found that when the guide vanes outlet in line with the volute tongue, the corresponding head is the highest, and the pressure fluctuation is the lowest. The mechanism of the clocking effect in the centrifugal pump with guide vanes is obtained by simplifying the hydrofoil. It is found that when the downstream hydrofoil leading edge is always interfered with by the upstream hydrofoil wake, the wake with low energy mixes the boundary layer with low energy, which causes small-pressure pulsation. The results could be used for the operation of centrifugal pumps with guide vanes.
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Ngo, Tu Thien, Tianjun Zhou, Junho Go, Hap Van Nguyen e Geun Sik Lee. "Improvement of the Steel-Plate Temperature During Preheating by Using Guide Vanes to Focus the Flame at the Outlet of a Gas Torch". Energies 12, n. 5 (5 marzo 2019): 869. http://dx.doi.org/10.3390/en12050869.
Testo completoAbstract (sommario):
The temperature distribution on a steel plate during a preheating process was comparedusing gas torch models with and without guide vanes. Numerical simulations were done usingANSYS FLUENT software, and experiments were done using thermal images obtained by aTVS-200EX infrared thermal camera. Liquefied petroleum gas (LPG) was used as fuel for the gastorch in the simulation and experiment. The temperature distribution on the steel plate and theflame region were first compared. The temperature increase caused by the flame concentrationwith the guide vanes was 65 C. The transient and steady-state temperature distribution on theback side of the steel plate were then examined. The results showed good agreement between thesimulation and experimental results. At steady state, the back-side temperature deviation of thesteel plate between the numerical simulation and experimental results was approximately 4.9%.The effects of the equivalence ratio (Φ), Reynolds number (Re), and the downstream distance ratioof the combustion gas from the torch outlet to the steel plate (H/d) on the temperature distributionwere also investigated. The highest temperature distribution was found in stoichiometriccombustion. The temperature of the plate increased as the Reynolds number increased from 2368 to4876 but decreased as the distance ratio (H/d) increased from 25 to 75. The guide vane angles at thegas torch outlet were from 30 to 60 degrees, and the angle of 40 degrees resulted in the highesttemperature of the steel plate.
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Xiao, Wei, Shaocheng Ren, Liu Chen, Bin Yan, Yilin Zhu e Yexiang Xiao. "Analysis of the Flow Behavior and Pressure Fluctuation of a Pump Turbine with Splitter Blades in Part-Load Pump Mode". Energies 17, n. 10 (16 maggio 2024): 2402. http://dx.doi.org/10.3390/en17102402.
Testo completoAbstract (sommario):
The internal flow of a pump turbine is unstable in part-load pump mode for small guide-vane openings, and the strong vibration caused by pressure pulsation is related to the safe and stable operation of the unit. A pump turbine with a six-splitter-blade runner was chosen for unsteady simulation analyses. A standard k-epsilon turbulence model was adopted to study the unsteady flow and pressure pulsation in part-load pump mode. The predicted results show that the flow in the draft tube and the runner with splitter blades was relatively stable and the flow of the blade-to-blade channel was symmetrical. When the inlet and outlet velocity distribution of the vanes was not uniform, a vortex began to form in the stay-vane domain. The reason for this vortex formation is explained, and it is pointed out that the existence of the vortex and backflow leads to uneven velocity distribution. The unsteady calculation results showed that the pressure-pulsation peak-to-peak amplitudes in the vaneless area and guide vanes were much higher than those of other monitor points because of rotor–stator interference between the rotating runner and the vanes. In addition, the pulsation characteristics of the monitor points at different circumferential positions in the vaneless region were quite different. In the vaneless area, the velocity gradient along the circumferential direction was very large, and there was a phenomenon of backflow. Also, the pressure pulsation was 0.2 times that of the runner rotational frequency, and the blade-passing frequency was a third-order frequency. At the outlet of the guide vane, the pressure pulsation was mainly of a low frequency with a complex vortex flow. Finally, the pressure pulsation began to decrease rapidly in the stay-vane region.
28
Xu, Lei, Tao Jiang, Chuan Wang, Dongtao Ji, Wei Shi, Bo Xu e Weigang Lu. "Experiment and Numerical Simulation on Hydraulic Loss and Flow Pattern of Low Hump Outlet Conduit with Different Inlet Water Rotation Speeds". Energies 15, n. 15 (25 luglio 2022): 5371. http://dx.doi.org/10.3390/en15155371.
Testo completoAbstract (sommario):
The rotation speed of water at the inlet of the low hump outlet conduit has a great effect on its hydraulic performance. Therefore, the influence of different inlet water rotation speeds on hydraulic loss and flow pattern of low hump outlet conduit is studied in this paper. By solving RANS equations and the RNG k-ε turbulence model, the hydraulic loss and 3D flow field of the low hump outlet conduit were calculated under different inlet water rotation speeds. To verify the numerical results, the model tests of low hump outlet conduit with different guide vanes were conducted. The results show that along with the growth of inlet water rotation speed, the hydraulic loss of outlet conduit will firstly decrease by degrees and then increase dramatically, the vortex location moves from the whole bottom of the descent segment to the right bottom of descent segment and the vortex area becomes smaller, the flow pattern of the whole conduit is improved obviously. The hydraulic loss and flow field of numerical simulation are consistent with those of the model test. Because of its great influence on hydraulic performance, inlet water rotation speed must be taken into consideration in the hydraulic optimization design of guide vane and low hump outlet conduit.
29
SHIBA, Masata, Masanori KUDO, Kotaro SATO, Kazuhiko YOKOTA e Koichi NISHIBE. "Oscillation Characteristics of Flow Downstream of Annular Guide Vanes with an outlet Pipe". Proceedings of the Fluids engineering conference 2016 (2016): 0212. http://dx.doi.org/10.1299/jsmefed.2016.0212.
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Khaletskiy, Yu D., e Ya S. Pochkin. "Fan noise reduction of an aircraft engine by inclining the outlet guide vanes". Acoustical Physics 61, n. 1 (gennaio 2015): 101–8. http://dx.doi.org/10.1134/s1063771014060098.
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OHASHI, Yuki, Masanori KUDO, Kotaro SATO, Kazuhiko YOKOTA e Koichi NISHIBE. "1605 Flow Characteristics Downstream of Annular Inlet Guide Vanes with an Outlet Pipe". Proceedings of Conference of Hokuriku-Shinetsu Branch 2016.53 (2016): _1605–1_—_1605–5_. http://dx.doi.org/10.1299/jsmehs.2016.53._1605-1_.
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Cheng, Xiaorui, Boru Lv, Chenying Ji, Ningning Jia e Dorah N. "Influence of Circumferential Placement Position of Guide Vanes on Performance and Dynamic Characteristics of Nuclear Reactor Coolant Pump". Mathematical Problems in Engineering 2020 (29 febbraio 2020): 1–12. http://dx.doi.org/10.1155/2020/3786745.
Testo completoAbstract (sommario):
In order to study the influence of the circumferential placement position of the guide vane on the flow field and stress-strain of a nuclear reactor coolant pump, the CAP1400 nuclear reactor coolant pump is taken as the research object. Based on numerical calculation and test results, the influence of circumferential placement position of the guide vane on the performance of the nuclear reactor coolant pump and stress-strain of guide vanes are analyzed by the unidirectional fluid-solid coupling method. The results show that the physical model and calculation method used in the study can accurately reflect the influence of the circumferential placement position of the guide vane on the nuclear reactor coolant pump. In the design condition, guide vane position has a great influence on the nuclear reactor coolant pump efficiency value, suction surface of the guide vane blade, and the maximum equivalent stress on the hub. However, it has a weak effect on the head value, pressure surface of the guide vane blade, and the maximum equivalent stress on the shroud. When the center line of the outlet diffuser channel of the case is located at the center of the outlet of flow channel of the guide vane, it is an optimal guide vane circumferential placement position, which can reduce the hydraulic loss of half of the case. Finally, it is found that the high stress concentration area is at the intersection of the exit edge of the vane blade and the front and rear cover, and the exit edge of the guide vane blade and its intersection with the front cover are areas where the strength damage is most likely to occur. This study provides a reference for nuclear reactor coolant pump installation, shock absorption design, and structural optimization.
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Wang, Shicheng, Junhu Yang e Guobin Xu. "Optimization of geometrical parameters of positive guide vane for multi-stage pump as turbine based on orthogonal test". Journal of Physics: Conference Series 2854, n. 1 (1 ottobre 2024): 012059. http://dx.doi.org/10.1088/1742-6596/2854/1/012059.
Testo completoAbstract (sommario):
Abstract Multi-stage pumps as turbines (PAT) are commonly employed in the petrochemical, coal chemical, and other process industries to recover liquid residual pressure energy. This study focused on improving the performance of multi-stage PAT, specifically targeting the slope of the power-flow(P-Q) curve and hydraulic efficiency at the rated flow point. A two-stage PAT was selected as the research object for this study. According to the relationship between the power and the geometrical parameters of the positive guide vane derived based on the basic equation of the multi-stage PAT, four parameters of the positive guide vane were selected as the test factors for the orthogonal experimental study. A four-factor, three-level orthogonal table of type L9(34) was established. Using Fluent software and the RNG k-ε turbulence model to carry out numerical calculations of constant flow, the results showed that: for the slope of the P-Q curve, the influence of geometric parameter factors of the positive guide vane are in the order of the throat area, the outlet placement angle, the positive guide vanes number, and the base circle diameter; and for the hydraulic efficiency, the influence of geometric parameter factors of the positive guide vane are in the order of the throat area, the positive guide vanes number, the outlet placement angle, and the base circle diameter of the positive guide vane. At the rated flow point, the P-Q curve of the optimized solution decreased by 0.24, resulting in a flatter curve and a 0.3% increase in hydraulic efficiency. There was little change in the vicinity at the rated flow point. The best efficiency point of the optimized scheme is biased toward the high flow rate, the efficiency is increased by 1.85%, and the best efficiency zone is wider. Therefore, selecting appropriate positive guide vane geometry parameters can flatten the P-Q curve, improve internal flow, and enhance hydraulic efficiency.
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Čudina, M. "Noise generation in vane axial fans due to rotating stall and surge". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 215, n. 1 (1 gennaio 2001): 57–64. http://dx.doi.org/10.1243/0954406011520517.
Testo completoAbstract (sommario):
A characteristic of axial flow fans is instabilities in their performance and noise in partial load operation. These instabilities are a consequence of rotating stall created in the rotor blade and/or in the guide vane cascade. At some operating conditions the rotating stall caused the appearance of a surge representing the lowest region of fan operating stability. The rotating stall and especially surge caused a steep increase in the emitted noise and lowered the performance of the fan. The present paper highlights the rotating stall generation phenomenon and its influence on the emitted total noise level and noise spectra for axial flow fans with inlet and outlet guide vanes.
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Zhang, Huiyan, Fan Meng, Yunhao Zheng e Yanjun Li. "The Cavitation-Induced Pressure Fluctuations in a Mixed-Flow Pump under Impeller Inflow Distortion". Machines 9, n. 12 (30 novembre 2021): 326. http://dx.doi.org/10.3390/machines9120326.
Testo completoAbstract (sommario):
To reduce cavitation-induced pressure fluctuations in a mixed-flow pump under impeller inflow distortion, the dynamic pressure signal at different monitoring points of a mixed-flow pump with a dustpan-shaped inlet conduit under normal and critical cavitation conditions was collected using high-precision digital pressure sensors. Firstly, the nonuniformity of the impeller inflow caused by inlet conduit shape was characterized by the time–frequency-domain spectra and statistical characteristics of pressure fluctuation at four monitoring points (P4–P7) circumferentially distributed at the outlet of the inlet conduit. Then, the cavity distribution on the blade surface was captured by a stroboscope. Lastly, the characteristics of cavitation-induced pressure fluctuation were obtained by analyzing the time–frequency-domain spectra and statistical characteristic values of dynamic pressure signals at the impeller inlet (P1), guide vanes inlet (P2), and guide vanes outlet (P3). The results show that the flow distribution of impeller inflow is asymmetric. The pav values at P4 and P6 were the smallest and largest, respectively. Compared with normal conditions, the impeller inlet pressure is lower under critical cavitation conditions, which leads to low pav, pp-p and a main frequency amplitude at P1. In addition, the cavity covered the whole suction side under H = 13.6 m and 15.5 m, which led the pp-p and dominant frequency amplitude of pressure fluctuation at P2 and P3 under critical cavitation to be higher than that under normal conditions.
36
Jin, Weiya, Zijian Mao, Shuiqing Zhou, Tianle Zhang, Yinjie Hu e Zhenghui Wu. "Research on Multi-Optimal Project of Outlet Guide Vanes of Nuclear Grade Axial Flow Fan Based on Sensitivity Analysis". Applied Sciences 12, n. 6 (16 marzo 2022): 3029. http://dx.doi.org/10.3390/app12063029.
Testo completoAbstract (sommario):
Nuclear grade axial flow fans are widely used in nuclear power plants for ventilation and heat dissipation and have the advantages of high efficiency and high flow rates. A nuclear grade axial flow fan with OGVs (outlet guide vanes) can recover the kinetic energy of the dynamic impeller outlet winding to increase the ventilator pressure, thus improving the ventilator efficiency; therefore, the OGVs play an essential role in the performance of the axial flow fan. Based on accurate numerical simulations, an MRGP approximation model was developed to analyse the factors affecting the OGVs duct and optimise the guide vane structure, combined with the Sobol method for sensitivity analysis. The experiments and numerical simulations show that the total pressure of the optimised model increases by 154 Pa, and the noise decreases by 4.1 dB. The multi-objective optimisation method using the parametric approach and combining it with the MRGP model is highly reliable. It provides a key design direction for optimising nuclear grade axial flow fans.
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Sznajder, Janusz. "Simulations of Hot-Gas Flow in Internally Cooled Cascade of Turbine Vanes". Journal of KONES 26, n. 2 (1 giugno 2019): 151–58. http://dx.doi.org/10.2478/kones-2019-0044.
Testo completoAbstract (sommario):
Abstract An experiment in cooling of gas turbine nozzle guide vanes was modelled numerically with a conjugate viscous-flow and solid-material heat conduction solver. The nozzle vanes were arranged in a cascade and operated in high-pressure, hot-temperature conditions, typical for first turbine stage in a flow of controlled-intensity, artificially-generated turbulence. The vane cooling was internal, accomplished by 10 channels in each vane with cooling-air flow. Numerical simulations of the experiment were conducted applying two turbulence models of the k-omega family: k-omega-SST and Transition SST implemented in the ANSYS Fluent solver. Boundary conditions for the simulations were set based on conditions of experiment: total pressures and total temperature on inlet to cascade, static pressure on the outlet of the cascade and heat flux on the surface of cooling channels. The values of heat flux on the surface of cooling channels were evaluated based on Nusselt numbers obtained from experiment and varied in time until steady-state conditions were obtained. Two test cases, one with subcritical outlet flow, and another one, with supercritical outlet flow were simulated. The result of experiment – distributions of pressure, surface temperature, and heat transfer coefficients on the vane external surface were compared to results of numerical simulations. Sensitivity of the vane surface temperatures and heat transfer coefficients to turbulence models and to boundary-condition values of parameters of turbulence models: turbulence energy and specific dissipation of turbulence energy was also studied.
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Acharya, N., S. Gautam, S. Chitrakar, C. Trivedi e O. G. Dahlhaug. "Application of hydro-abrasive erosion model from IEC 62364:2019 standard in Francis turbines". IOP Conference Series: Earth and Environmental Science 1079, n. 1 (1 settembre 2022): 012008. http://dx.doi.org/10.1088/1755-1315/1079/1/012008.
Testo completoAbstract (sommario):
Abstract Hydro-abrasive erosion in hydraulic turbines is critical and one of the prominent issue due to its association with maintenance costs and production losses in the hydropower plant. IEC 62364:2019* standard guide focuses mainly on hydroelectric powerplant equipment and provides the standard on particle abrasion rates on several combinations like operating conditions, component materials properties, water quality among many factors. With the consideration of different critical parameters, a theoretical model of abrasion rate on hydraulic turbines is proposed by IEC 62364:2019. Present study is conducted to elucidate the several terms used in the theoretical model of abrasion rate for Francis turbine as per the guidelines. The work has taken account into run-off river (RoR) hydropower plant consisting of Francis runner operating in sediment laden rivers in the Himalayan area. Theoretical expected erosion depth for runner inlet, runner outlet, guide vanes facing plates and labyrinth seals is calculated. Characteristic velocities of runner (Wrun) and guide vanes (Wgv) were estimated to be 32.26 m/s and 35.05 m/s respectively. Particle load was calculated based upon the sampling data available from the site. Measurement data from field observation during overhauling was used for comparison with the data calculated from empirical relation. For 229 hours operation of turbine, observed abrasion depth varies from 8.1 mm in guide vanes to 1.5 mm in labyrinth ring corresponding to calculated values of 7.53 mm and 1.89 mm for same components. Results shows good correlation among calculated values from IEC and measured values from the site. An optimized solution can thus be devised based on the evaluation of hydro-abrasive erosion along with energy production and maintenance expenses. *IEC 62364:2019. Hydraulic machines - Guidelines for dealing with hydro-abrasive erosion in Kaplan, Francis, and Pelton turbines. Edition 2.0 (March 2019) International Electrotechnical Commission, Geneva, Switzerland [1]
39
Zhang, Ling, Peng Jie Huang, Hai Qiang Li e Yun Peng Diao. "CFD Analysis of Impeller Internal Flow Field in Multistage Pump with Inducer". Advanced Materials Research 1070-1072 (dicembre 2014): 1937–40. http://dx.doi.org/10.4028/www.scientific.net/amr.1070-1072.1937.
Testo completoAbstract (sommario):
Based on the three-dimensional Reynolds-Averaged N-S equations and the standard k-ε turbulence model, the inner flow of a multistage vane water centrifugal pump was simulated. The distribution law of inner flow was analyzed by using the SIMPLEC algorithm and multiple reference frame (MRF) model provided by CFD software Fluent. The pressure and velocity distribution law in impeller and vane diffuser are obtained. Results indicated that the lowest pressure area , where cavitation was easy to occur, was in the inlet of the first impeller blade back. There is reverse flow in outlet of impeller. An area of low pressure can be seen in the inlet of return guide vanes. The guide vane could reduce fluid velocity and eliminated fluid rotating component.
40
Polacsek, C., A. Cader, M. Buszyk, R. Barrier, F. Gea-Aguilera e H. Posson. "Aeroacoustic design and broadband noise predictions of a fan stage with serrated outlet guide vanes". Physics of Fluids 32, n. 10 (1 ottobre 2020): 107107. http://dx.doi.org/10.1063/5.0020190.
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Roger, Michel, e Benjamin François. "Combined analytical models for sound generation and transmission in cambered axial-flow outlet guide vanes". European Journal of Mechanics - B/Fluids 61 (gennaio 2017): 218–25. http://dx.doi.org/10.1016/j.euromechflu.2016.10.006.
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Zhai, Lulu, Chao Lu, Jia Guo, Zuchao Zhu e Baoling Cui. "Flow Characteristics and Energy Loss of a Multistage Centrifugal Pump with Blade-Type Guide Vanes". Journal of Marine Science and Engineering 10, n. 2 (28 gennaio 2022): 180. http://dx.doi.org/10.3390/jmse10020180.
Testo completoAbstract (sommario):
Multistage pumps with blade-type guide vanes are widely used in offshore oil production, the petrochemical and coal-chemical industries, and nuclear power fields for its advantages of large flow rate, high pressure, and excellent operation stability. However, the internal flow of this kind of pump is complex; in particular, the hydraulic, flow, and pressure pulsation characteristics of the different stages are quite different, which has a great impact on the design and performance predictions of this kind of pump. Thus, in this paper, the hydraulic performance, unsteady flow characteristics, evolution of vortex structures and pressure pulsation characteristics in a 10 stage centrifugal pump are investigated numerically. The results show that inverse flow, jet-wake flow, and rotor-stator interaction flow are the key factors causing energy loss and efficiency decline at every stage and in the whole pump. The vortex evolution at the rotor–stator interaction regions is actually the process that the vortex structures fall off and impact on the pressure surface at the leading edge of the guide vane blade at a frequency that equals to the impeller blade passing frequency. Furthermore, under the actions of the guide vane with confluence cavity, the pressure pulsation within the final-stage guide vane contains low-frequency components with large bandwidths, which mainly results from the confluence flow disturbance at the outlet of the cylindrical guide passage.
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Pandey, A., S. Gautam, S. Chitrakar, N. Acharya e P. L. Bijukchhe. "Numerical Investigation of Flow Behaviour and Erosion Potential in the Side-Wall Clearance Between Guide Vane and Runner". IOP Conference Series: Materials Science and Engineering 1279, n. 1 (1 marzo 2023): 012009. http://dx.doi.org/10.1088/1757-899x/1279/1/012009.
Testo completoAbstract (sommario):
Abstract In the hydropower plants exposed to excessive sediment concentration, the components of Francis turbines, especially the regions of Guide Vanes (GVs) and Runner Vanes (RVs) are severely eroded. The side-wall clearance between GV and runner is present in these turbines to separate the rotating and stationary components. The height difference between the runner inlet and GV outlet covers, introduced during the fabrication or assembly process might play a crucial role in accelerating the erosion process in these components. This study is focused on numerical analysis of simplified geometries that replicate different scenarios of the height difference and consequent flow behaviour in the side-wall clearance of Francis turbines. The numerical analysis is done in OpenFOAM using the available solver adopting the finite volume method (FVM). The numerical study is compared with the experimental results obtained from Rotating Disc Apparatus (RDA). The numerical analysis shows the vortex formation in the side-wall clearance region which traps the sediment particles. Such vortex formation causes erosion in the region. The vortex formation and flow behaviour in different height difference scenarios vary with each other and so does the erosion pattern in the experimental results.
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Liu, Zhen, Xiangyuan Zhu, Jiying Liu, Moon Keun Kim e Wei Jiang. "A Numerical Investigation of the Influence of Diffuser Vane Height on Hydraulic Loss in the Volute for a Centrifugal Water Supply Pump". Buildings 14, n. 8 (24 luglio 2024): 2296. http://dx.doi.org/10.3390/buildings14082296.
Testo completoAbstract (sommario):
The energy efficiency of water supply systems in high-rise residential buildings has become a significant concern for sustainable development in recent times. This work presents a numerical investigation on the influence of diffuser vane height on flow variation and hydraulic loss in the volute for a water supply centrifugal pump. Experiments and numerical simulations were conducted with four different vane height ratios. The numerical results were validated against experimental data. The hydraulic losses of different flow components were numerically evaluated at varying guide vane blade heights. The changes in flow patterns within the volute and the resulting discrepancies in hydraulic losses due to variations in the inlet flow conditions at different blade heights were studied. The findings indicate that the total pressure drop within the volute is affected significantly. Compared to traditional guide vanes, the reduced height vanes can reduce the hydraulic loss in the volute by nearly 75%. Once the vane height is reduced, the high-pressure gradient is improved, and the small-scale vortex vanishes. The influence area of the large-scale vortex in the volute outlet pipe decreases, leading to a weakening of the deflection of the main flow and ultimately resulting in reduced hydraulic loss.
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Li, Xiaojun, Tao Ouyang, Yanpi Lin e Zuchao Zhu. "Interstage difference and deterministic decomposition of internal unsteady flow in a five-stage centrifugal pump as turbine". Physics of Fluids 35, n. 4 (aprile 2023): 045136. http://dx.doi.org/10.1063/5.0150300.
Testo completoAbstract (sommario):
A five-stage centrifugal pump is utilized to investigate the interstage flow characteristics of the multistage centrifugal pump as turbine (PAT). The simulation results of performance are verified by comparing with the experimental results. Owing to the distinct structural attributes, significant differences in flow occur between the first stage and the other stages of the multistage PAT. To enhance the understanding of these disparities and explore their repercussions, this study focuses on analyzing the flow within the impellers in the first and second stages by a deterministic analysis. The main conclusions are as follows: The discrepancies in the inflow conditions are the major reason for the dissimilarities in the flow of impellers between stages. The impact loss generated by the misalignment between the positive guide vane outlet angle and the impeller inlet angle leads to flow deviation between impeller passages and affects the internal flow pattern. The unsteadiness under low flow rates is mostly produced by the spatial gradient of the blade-to-blade nonuniformities, which is relevant to the relative position between blades and the positive guide vanes. At high flow rates, especially in the second-stage impeller, the pure unsteady term is the primary cause of flow unsteadiness as a result of the flow separation induced by interactions between the blades and the positive guide vanes. This study can provide some references for the practical operation and performance optimization of the multistage PATs in the future.
46
Ru, Songnan, Shaozheng Zhang, Kaitao Zhou, Xingxing Huang, Wenlong Huang e Zhengwei Wang. "Numerical Study on the Flow and Structural Characteristics of a Large High Head Prototype Pump-Turbine under Different Operating Conditions". Processes 11, n. 10 (13 ottobre 2023): 2970. http://dx.doi.org/10.3390/pr11102970.
Testo completoAbstract (sommario):
During the operation of pumped storage power stations, complex operating conditions can lead to different internal flow characteristics, which can cause different vibration characteristics or even damage to the structural components of the pump-turbine units. The time–frequency characteristics of the structural components’ response are of great significance for the safe operation of the unit. In this study, a three-dimensional flow field and structural field model of a large high head prototype pump-turbine is built in order to study the flow and the flow-induced dynamic response characteristics in different turbine operating conditions. The analyzed results show that the maximum deformation occurs at the inner head cover, and the maximum value of stress is located at the fillets on the outlet side of the stay vanes. Under the 50% load condition, the vortices in the runner caused by changes in the opening of the guide vanes result in the main response frequency of 4 fn of the stationary components. The research results can provide references for the structural optimization design of other pump-turbine units.
47
Wang, Xiuli, Yonggang Lu, Rongsheng Zhu, Yuanyuan Zhao e Qiang Fu. "Study on pressure pulsation characteristics of reactor coolant pump during the idling transition process". Journal of Vibration and Control 25, n. 18 (21 giugno 2019): 2509–22. http://dx.doi.org/10.1177/1077546319858856.
Testo completoAbstract (sommario):
The idling characteristic of the reactor coolant pump is one of the important indicators for the safe operation of the nuclear power system. The idling transition process of the reactor coolant pump under the power failure accident condition belongs to the transient flow process. During most of the time of the idling transition process, the parameters of flow, rotating speed, and head are all nonlinear changes, and the study of the idling change law is extremely difficult. This paper introduces the nonlinear inertia transient phase of the reactor coolant pump and the principle of wavelet analysis. Based on the experimental results of the idling transition process, the polynomial fitting of the flow curve and the rotating speed curve is fitted, and the idling transient equation is established which is a boundary condition for computational fluid dynamics simulation of the nonlinear idling transient stage of the reactor coolant pump with different types of guide vanes. The signal fluctuation of pressure pulsation time-domain change at the volute outlet in different sub-bands is analyzed by means of a fast, discrete wavelet transform, and the effects of different vane optimizations in different idling stages are analyzed. It was found that the pressure fluctuation amplitude of each sub-frequency range of pump outlet in the model of the shunt guide vane is significantly smaller than that of the normal guide vane.
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Wang, Chun Lin, Chang Jun Li, Jian Ding e Dong Liu. "Circulation Distribution of High Specific Speed Mixed-Flow Pump". Applied Mechanics and Materials 130-134 (ottobre 2011): 1982–85. http://dx.doi.org/10.4028/www.scientific.net/amm.130-134.1982.
Testo completoAbstract (sommario):
The load distribution of the impeller and the shape of blade bone surface as well as the pump performance are determined by the circulation distribution from the impeller inlet to the outlet. However, perfect conclusions about optimal forms of the circulation distribution have not been seen yet. In this paper, three kinds of circulation distributions were studied. Three mixed flow pump impellers with high specific speed were designed according to the circulation distributions, and the models of the three pumps were built and modeled in the commercial CFD code ANSYS-CFX 11.0. The flow field in the pumps has been investigated using large eddy simulation (LES). Experiment was carried out on one model. And the performance curves predicted by LES were compared with the experimental data, and good agreements were achieved. The results show that: there is a low pressure area at impeller outlet. The pressure distribution along the circumferential direction was asymmetry at the front-end area of guide vanes, but it becomes uniform at the end of guide vane. The bearing pressure on the pressure side of the model 2 is lower, and the pressure distribution of model 1 is more asymmetry and there is a clear low pressure area at outlet of blade; Cavitation performance of model 2 is better, and the maximum efficiency is also the highest, but the hump is more serious; Model 1 has a widest area of high effective area.
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Luo, Can, Hao Liu, Li Cheng, Chuan Wang, Weixuan Jiao e Di Zhang. "Unsteady Flow Process in Mixed Waterjet Propulsion Pumps with Nozzle Based on Computational Fluid Dynamics". Processes 7, n. 12 (3 dicembre 2019): 910. http://dx.doi.org/10.3390/pr7120910.
Testo completoAbstract (sommario):
The unsteady flow process of waterjet pumps is related to the comprehensive performance and phenomenon of rotating stall and cavitation. To analyze the unsteady flow process on the unsteady condition, a computational domain containing nozzle, impeller, outlet guide vane (OGV), and shaft is established. The surface vortex of the blade is unstable at the valley point of the hydraulic unstable zone. The vortex core and morphological characteristics of the vortex will change in a small range with time. The flow of the best efficiency point and the start point of the hydraulic unstable zone on each turbo surface is relatively stable. At the valley point of the hydraulic unstable zone, the flow and pressure fields are unstable, which causes the flow on each turbo surface to change with time. The hydraulic performance parameters are measured by establishing the double cycle test loop of a waterjet propulsion device compared with numerical simulated data. The verification results show that the numerical simulation method is credible. In this paper, the outcome is helpful to comprehend the unsteady flow mechanism in the pump of waterjet propulsion devices, and improve and benefit their design and comprehensive performance.
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Mandoc, Andrei Cristian, Raluca Lucia Maier, Constantin Gheorghe Opran, Vicenzo Delle Curti e Giuseppe Lamanna. "BIOMIMETIC CELLULAR STRUCTURES FOR TURBINE SYSTEM COMPONENTS". International Journal of Modern Manufacturing Technologies 14, n. 2 (20 dicembre 2022): 151–58. http://dx.doi.org/10.54684/ijmmt.2022.14.2.151.
Testo completoAbstract (sommario):
The research aim is to investigate cellular structures inspired from nature, in order to improve the internal structural resistance of turbine system components (e.g. hydroelectric and gas turbine blades, OGV-Outer Guide Vanes, nacelles, gearboxes) with reduced mass. The investigations were conducted at laboratory level, utilizing two 3D printing technologies to acquire the desired cellular structures which were further tested for tensile, bending and impact resistance. The first selected technology was Fused Deposition Modelling with Continuous Filament Fabrication to obtain 3D printed parts, which can be reinforced with continuous carbon, glass, or Kevlar fibers. The second technology used is Digital Light Processing 3D printing, which uses photopolymer liquid resin that cures under digital light source. The main motivation of utilizing the 3D printing technologies is the desire of implementing rapid prototyping in the final manufacturing of the turbine system components with structural topological optimization and improved structural and dynamic efficiency through biomimetic inspired structures. Conventional polymeric composite manufacturing technologies are sometimes restrictive in the geometries they can produce, and there is a chance that additive manufacturing can step in and help create internal structures that could not be obtained through conventional manufacturing methods. New developed structural architectures could be manufactured for a specific application through 3D printing which allows for a high level of customization parameters, including the possibility to use continuous carbon, glass and Kevlar fiber to create the geometrical pattern. All these, combined with conventional composite manufacturing technologies, could lead to obtain better end results.