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About 357 papers for “diffuser vanes”
Kim F. Young · Loughborough University Institutional Repository (Loughborough University) · 1988
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.
Cited by 2Open access
Wangzhi Zou, Xiao He, Wenchao Zhang et al. · Proceedings of the Institution of Mechanical Engineers Part G Journal of Aerospace Engineering · 2019
The stability considerations of centrifugal compressors become increasingly severe with the high pressure ratios, especially in aero-engines. Diffuser is the major subcomponent of centrifugal compressor, and its performance greatly influences the stability of compressor. This paper experimentally investigates the roles of vanes in diffuser on component instability and compression system instability. High pressure ratio centrifugal compressors with and without vanes in diffuser are tested and analyzed. Rig tests are carried out to obtain the compressor performance map. Dynamic pressure measurements and relevant Fourier analysis are performed to identify complex instability phenomena in the time domain and frequency domain, including rotating instability, stall, and surge. For component instability, vanes in diffuser are capable of suppressing the emergence of rotating stall in the diffuser at full speeds, but barely affect the characteristics of rotating instability in the impeller at low and middle speeds. For compression system instability, it is shown that the use of vanes in diffuser can effectively postpone the occurrence of compression system surge at full speeds. According to the experimental results and the one-dimensional flow theory, vanes in diffuser turn the diffuser pressure rise slope more negative and thus improve the stability of compressor stage, which means lower surge mass flow rate.
Cited by 13
Ogboo Chikere Aja, Hussain H. Al‐Kayiem, Zainal Ambri Abdul Karim · Greater South Information System · 2018
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.
Cited by 0Open access
Tushar Goel, Daniel J. Dorney, Raphael T. Haftka et al. · Deep Blue (University of Michigan) · 2016
The performance of a diffuser in a pump stage depends on its configuration and placement within the stage. The influence of vane shape on the hydrodynamic performance of a diffuser has been studied. The goal of this effort has been to improve the performance of a pump stage by optimizing the shape of the diffuser vanes. The shape of the vanes was defined using Bezier curves and circular arcs. Surrogate model based tools were used to identify regions of the vane that have a strong influence on its performance. Optimization of the vane shape, in the absence of manufacturing and stress constraints, led to a nearly eight percent reduction in the total pressure losses compared to the baseline design by reducing the extent of the base separation.
Cited by 0Open access
Chun Jun Ji, Qi Zhou · Advanced materials research · 2012
the effect of the interference between the diffuser vanes with the volute tongue was studied in this paper, based on the 3-d model of the residual heat removal pump and the numerical flow analysis platform developed with the commercial CFD software NUMECA. Results indicate that poor matching of the diffuser vanes and the volute may cause serious flow losses. The relative position between the diffuser vanes and the volute was optimized by numerical experiments. Final modifications indicate that the efficiency is increased by 6.4%.
Cited by 0
Ikki YANAGIHARA, M. Takahashi, Shinichiro EJIRI et al. · The Proceedings of Mechanical Engineering Congress Japan · 2025
At off-design points, diffuser pumps often experience significantly restricted operating ranges due to the induction of unstable phenomena, such as diffuser rotating stall (DRS), caused by unsteady flow effects. This presents a major issue in various industries. This study aims to suppress the backflow from the diffuser vane outlet to the inlet, which contributes to the development of DRS. A CFD analysis was conducted on a modified diffuser featuring sweep-shaped holes. These holes extend from the leading edge of the diffuser vanes, pass through the vane interior, and exit via the vane's suction surface. The objective of this analysis was to investigate the effectiveness of this design in suppressing DRS. As a result, the number of backflows from the diffuser channel outlet was reduced at the 50% flow rate point. Furthermore, efficiency at the design point improved by a maximum of approximately 1.5%.
Cited by 0Open access
Chun Jun Ji, Qi Zhou · Advanced materials research · 2012
the effect of the interference between the diffuser vanes with the volute tongue was studied in this paper, based on the 3-d model of the residual heat removal pump and the numerical flow analysis platform developed with the commercial CFD software NUMECA. Results indicate that poor matching of the diffuser vanes and the volute may cause serious flow losses. The relative position between the diffuser vanes and the volute was optimized by numerical experiments. Final modifications indicate that the efficiency is increased by 6.4%.
Cited by 0
Prasad Mukkavilli, G. Rama Raju, A. Dasgupta et al. · 2002
Diffusers are found to play a significant role in the performance of centrifugal compressors. Extensive studies have been in progress in various research laboratories for improvement of performance with various types of diffusers. One such effort for study of performance of a centrifugal compressor stage with Low Solidity Diffuser (LSD) vanes is presented in this paper. The study was conducted at a tip mach number of 0.35. An exclusive test rig was set up for carrying out these flow studies. The LSD vane is formed using standard NACA profile with marginal modification at the trailing edge region. The study encompasses the variation of setting angle of the LSD vane and the vane solidity. The effect of solidity and the setting angle on overall stage performance is evaluated in terms of flow coefficient, head coefficient and efficiency normalised with respect to these parameters for the case of vaneless diffuser at design flow. Improvement in performance as well as static pressure recovery was observed with LSD as compared to vaneless diffuser configuration. It is concluded from these studies that there is an optimum solidity and stagger angle for the given stage with LSD vanes for the chosen configuration.
Cited by 10
Qifeng Ni, Anping Hou, Ye Tian et al. · 2013
A single stage centrifugal compressor has been designed for industrial use. Adjustable Inlet Guide Vanes (IGVs) and vaned diffusers were equipped to meet the requirement of large flow range, high efficiency and constant shaft speed. Both numerical calculations and experiments were implemented to get the performance of this new designed centrifugal compressor. The influence of adjustable IGVs and vaned diffusers on the stage performance characteristic was examined by numerical method. It is shown that numerical simulation results are close to the measured results and predict the stall limit well. The new centrifugal compressor has a comparatively high efficiency and wide operating range. Moreover, unilateral adjustment of either IGV pre-whirl angle or vaned diffuser stagger angle enables an increase in stable operating range opposed to the stage configuration with no adjustment. The combination of simultaneous adjustment of the IGVs and diffuser vanes can not only provide even wider flow range but also keep high efficiency. The identical working point can be operated at different IGV pre-whirl angles and diffuser stagger angles, hence the optimum adjustment schedule for the specified operating line was dug up to obtain an optimum efficiency. Detailed flow field analysis was performed to validated the suitable simultaneous adjustment combinations.
Cited by 3
S. M. Gunadal, M. Govardhan · Journal of Mechanical Science and Technology · 2019
Cited by 10
T.Y. Shigemoto · OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information) · 1965
mass flow with vane end clearances open. This decrease in mass flow was mitigated by increasing the vane angle. This was as expected since vane loading and reaction decrease with increasing vane angle. With the vane end clearances filled, there was about a 66% reduction in mass flow when the vane angle was decreased from 40/sup 0/ to 26/sup 0/. For the same decrease in vane angle the stator throat area decreased by about 50%. This result indicates that the rotor losses were increasing with decreasing vane angle. At design equivalent values of speed and pressure ratio, there was a penalty of about 4 points in total efficiency due to the vane end clearances of 1.1 and 1.9% of the vane height for the hub and tip sections, respectively. This penalty remained about constant over the range of vane angles investigated. Significant increases in total efficiency were obtained for both stator-vane end configurations as the vane angle was increased from 26/sup 0/. A peak total efficiency of about 0.91 was obtained at the vane angle of 45/sup 0/ with the vane end clearances filled. Results of static-pressure measurements and rotor-exit surveys showed that the rotor reaction was positive from hub to shroud for the vane angle of 45/sup 0/. Although high negative rotor incidence angles were obtained, the high positive rotor reactions would be expected to minimize the effects of increased losses due to incidence.
Cited by 0Open access
Ning He · International Journal of Fluid Mechanics Research · 2008
This paper presents a computational analysis of a high-speed centrifugal compressor stage where emphasis is focused on both the steady and unsteady flow investigations and on the effect of different number of diffuser vanes on the stage operating range. The simulations were carried out for a centrifugal stage with a backswept impeller and several diffusers with 11, 22 and 33 vanes. For the steady simulations, an averaging approach was used at the interface between the impeller and the diffuser. For the unsteady simulations, geometry scaling was used to deal with the problem of unequal pitch. As the number of diffuser vanes was increased, the pressure recovery coefficient in the semi-vaneless space at surge condition was found to reduce. Also, as the number of diffuser vanes was increased, the flow distortion became more pronounced in the vaneless and semi-vaneless space. It is proposed that this more distorted flow is harmful to the pressure recovery in the semi-vaneless space giving stages with more diffuser vanes narrower flow ranges. It was also found that the diffuser area ratio is not the dominant factor influencing the flow range when the number of diffuser vanes changes.
Cited by 0
H. Simon, Th. Wallmann, T. Mo ̈nk · Journal of Turbomachinery · 1987
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.
Cited by 55
Ying-Yuan Liu (8394045), Gang Yang (288797), Ying Xu (9172) et al. · Figshare · 2020
Cited by 0Open access
G. V. Ramana Murty, T. Ch. Siva Reddy, M. V. S. S. S. M. Prasad et al. · 2004
The results of experimental studies on a centrifugal compressor stage using uncambered constant thickness low solidity diffuser vanes (LSD) are reported in this paper. In the present work, efforts are concentrated for study of stage performance with LSD vanes for a typical compressor stage at a tip mach number of 0.35. The effect of solidity and setting angle on overall stage performance is evaluated in terms of flow coefficient, head coefficient and efficiency. The results were normalised with the data available at design flow using vaneless diffuser. Improvement in performance as well as static pressure recovery was observed with LSD vanes of the chosen configuration as compared to vaneless diffuser configuration. Variation of blade loading is studied from the measurements of static pressure on pressure and suction surfaces of LSD vane.
Cited by 0
Julian Stemmermann, Peter Jeschke · 2025
Abstract The influence of diffuser vanes on the stability behavior of an industrial centrifugal compressor (impeller outlet diameter d2 = 330 mm, machine Mach number Mu2 = 1.1 and pressure ratio πvaneless = 2.35) with IGV and volute is experimentally investigated with two different diffuser configurations: vaneless and vaned. Inlet tip recirculation was analyzed and found to be suppressed by the diffuser vanes on almost all performance curves. The instability phenomena are captured by 29 transient pressure transducers in the impeller and diffuser shroud. These measurements show that mild surge is suppressed by the diffuser vanes at low rotational speeds. The pressure transducers are also used to accurately identify rotating stall. The properties of rotating stall are analyzed in terms of number and rotational speed of the stall cells as well as their streamwise propagation through the compressor stage. The rotating stall properties are significantly influenced by the diffuser vanes. The cells co- and counter-rotate at slower rotational speed with the vaned diffuser. Counter-rotating cells emerge from the diffuser outlet and propagate upstream through the compressor. In contrast, co-rotating stall cells form at the impeller leading edge and propagate downstream through the compressor. In one operating point, there are even co- and counter rotating stall cells present that superpose. These results can be used to prevent potentially damaging operating conditions of future centrifugal compressor stages.
Cited by 0
N. Sitaram, J. M. Issac, M. Govardhan · Journal of Aerospace Sciences and Technologies · 2023
The present paper reports experimental investigations on the effect of diffuser vane height and its position on diffuser wall static pressures of a low speed centrifugal compressor. Apart from the standard types of diffusers, namely, vaneless, vane and low solidity vane diffusers, a partial vane diffuser, whose height is less than the diffuser width is also tested. The vane height of the partial vane diffuser is varied from 0.3, 0.4 and 0.5 times the diffuser width in vane and low solidity vane diffuser configurations. In addition, the effect of vane position is examined by fixing the partial vanes to the hub, shroud or hub and shroud. It is found that there is an optimum height for the diffuser vane height, which is found to be 0.3 times the diffuser width. The effect of position of the partial vanes on the hub or shroud on the diffuser wall static pressures is found to be negligible. However when partial vanes are fixed on the hub and shroud staggered at half spacing, the diffuser performance based on wall static pressures is improved substantially.
Cited by 2Open access
Wei Qin, Hiroshi Tsukamoto · Journal of Fluids Engineering · 1997
The fundamental analysis in the first report was extended to calculate the unsteady flow induced by the interaction between impeller blades and diffuser vanes/volute casing in a diffuser pump. The unsteady flow in the diffuser vane passage, as well as the volute casing, is assumed to be induced by the five kinds of singularities—the bound vortices distributed on the impeller blades, diffuser vanes and volute casing wall, the sources at volute outlet, and the free vortices shed from the trailing edge of diffuser vanes. Calculated unsteady pressures agree with the corresponding experimental data. And the calculated results showed the effects of the flow rate, volute casing and the radial gaps between impeller blade trailing edge and diffuser vane leading edge on the magnitude of unsteady pressure downstream of impeller.
Cited by 14
M. G. Khalafallah, Hindawi Saleh, Shimaa M. Ali et al. · Journal of Engineering and Applied Science · 2021
Abstract The aerodynamic losses in centrifugal compressors are mainly associated with the separated flow on the suction sides of impeller and diffuser vanes. The overall performance of such compressors can be improved by adding splitter vanes. The present work examines the effect of varying the geometrical location of the splitter vanes in the diffuser on the overall performance of a high-speed centrifugal compressor stage of a small gas turbine. To increase the pressure recovery through the diffuser, two radial sets of vanes are used. The first set of vanes (diffuser-1) is equipped with splitter vanes, placed mid-distance between the main vanes, while the vanes of the second set (diffuser-2) are conventional vanes. Flow through the compressor was simulated using the ANSYS 19 workbench program. Flow characteristics and compressor performance were obtained and analyzed for different circumferential positions of the splitting vanes relative to the main vanes of diffuser-1. The study covered seven positions of the splitter vanes including the original design of the diffuser where the splitter vanes were located at mid-distance between the main vanes. The analysis shows that, at design conditions, selecting the position of the splitter vanes to be nearer to the pressure side of the main vanes improves the stage performance. In the present study, locating the splitters at 33% of the angular distance between the main vanes leads to the best performance, and a significant improvement in the overall stage performance is recorded. The pressure recovery coefficient is raised by about 17%, the pressure ratio is increased by about 1.13%, and the stage efficiency is increased by about 2.01%, compared to the original splitter position. Performance improvement is related to the suppression of the flow separation and the more uniformity of flow. On the contrary, further moving the splitter closer to the main blade, the pressure recovery coefficient is decreased by about 2% than the position of 33% of the angular distance, but still higher than the original position by about 15% and a limited improvement in the compressor performance is noticed. Moving the splitter far out the main blade annihilates the static pressure recovery of the diffuser by about 2:7% compared with the original position. So, for the investigated compressor, the best position of the splitter blade in the circumferential direction, which provides the best stage performance in our parametric analysis, is not necessary to be at the mid-angular distance between the diffuser’s main blades, but it is achieved by moving the splitter to about 33% of the angular distance where the diminished loss from the suppressed flow separation is more prevailing and the instigated friction losses from splitter surfaces are less critical.
Cited by 6Open access
M. Zhang, H. Wang, Hiroshi Tsukamoto · 2002
The 2-D vortex method and the commercially available CFD software are applied to calculate unsteady hydrodynamic forces on a diffuser pump impeller and the pressure fluctuations caused by the interaction between the impeller and the diffuser vanes. Calculated pressure and fluid forces on the impeller are compared with measured ones. The numerical analysis yields fairly accurate predictions of the fluid forces and the pressure fluctuations in diffuser passages and the pipe systems. It has been demonstrated that the fluid forces caused by the interaction between the rotor and stator vanes are small when the number of vanes on impeller and diffuser is identical. In this case, however, the local pressure fluctuations are larger in diffuser passages and the pipe systems.
Cited by 10