High-efficiency design of a mixed-flow pump has been carried out based on numerical analysis of a three-dimensional viscous flow.For analysis,the Reynolds-averaged Navier-Stokes equations with a shear stress transport...High-efficiency design of a mixed-flow pump has been carried out based on numerical analysis of a three-dimensional viscous flow.For analysis,the Reynolds-averaged Navier-Stokes equations with a shear stress transport turbulence model were discretized by finite-volume approximations.Structured grid system was constructed in the computational domain,which has O-type grids near the blade surfaces and H/J-type grids in other regions.The numerical results were validated with experimental data for the heads and hydraulic efficiencies at different flow coefficients.The hydraulic efficiency at the design flow coefficient was evaluated with variation of the geometric variables,i.e.,the area of the discharge and length of the vane in the diffuser.The result has shown that the hydraulic efficiency of a mixed-flow pump at the design condition is improved by the modification of the geometry.展开更多
As the geometry of the volute of turbocharger compressor is non-axisymmetric,it causes a distortion at the outlet of the diffuser and influences the upstream components.A distortion model in which a pressure distortio...As the geometry of the volute of turbocharger compressor is non-axisymmetric,it causes a distortion at the outlet of the diffuser and influences the upstream components.A distortion model in which a pressure distortion was applied as outlet boundary condition was established to simulate the distortion induced by the volute.It turned out to be sufficient to impose a circumferentially asymmetric pressure distribution at the outlet of the diffuser to replace the volute.Based on the distortion model which was verified,the influence of the amplitude of the distortion on the performance of centrifugal compressor was studied in detail.The results show that the distortion severely harms aerodynamic stability of the investigated compressor.The larger the amplitude of the distortion,the worse the performance of the compressor.The distortion induced by asymmetric volute propagates to upstream components and causes local flow separation at part of diffuser and impeller,and then causes the compressor surge.When the amplitude of the volute distortion is 10%,the stable flow range of the centrifugal compressor decreases to near zero.To authors’knowledge,the relationship between the compressor performance and distortion amplitude is first obtained quantitatively,which provides evidence to improve the performance of turbocharger compressor by decreasing the distortion induced by asymmetric volute.展开更多
Enhancing stall margin has a great importance for the development of turbo compressors. The application of circumferential grooved casing treatment(CGCT) is a useful method of increasing the stable operating range of ...Enhancing stall margin has a great importance for the development of turbo compressors. The application of circumferential grooved casing treatment(CGCT) is a useful method of increasing the stable operating range of the compressor, and the effectiveness of this kind of casing treatment have been proved by numerous experiments. In this paper, a single circumferential casing groove is placed along the shroud side of the vaned diffuser. To clarify the effect of circumferential groove on the centrifugal compressor stability and corresponding flow mechanism, numerical investigations with different radial location, axial depth and radial width were carried out to compare the results. The computational fluid dynamics(CFD) analyses results show that the centrifugal compressor with a single circumferential groove in diffuser passage can extend stable operating range while the efficiency over the whole operating range decreases a little. Efforts were made to study blade level flow mechanisms to determine how the circumferential groove impacts the compressor's stall margin(SM) and performance. Some comparisons of the flow features with different parameter of grooved casing treatment are performed, and the results indicate that the low energy flow in the tip clearance is sucked into the groove and the area of the low energy fluid region shrinks, which helps to improve the stall margin of the centrifugal compressor. The numerical results showed that a combination of position,width and depth of circumferential groove will maximize stall margin improvement(SMI) of the centrifugal compressor.展开更多
基金supported by the Korea Institute of Industrial Technology Evaluation and Planning (ITEP) grant funded by the Ministry of Knowledge Economy (Grant No.10031771)
文摘High-efficiency design of a mixed-flow pump has been carried out based on numerical analysis of a three-dimensional viscous flow.For analysis,the Reynolds-averaged Navier-Stokes equations with a shear stress transport turbulence model were discretized by finite-volume approximations.Structured grid system was constructed in the computational domain,which has O-type grids near the blade surfaces and H/J-type grids in other regions.The numerical results were validated with experimental data for the heads and hydraulic efficiencies at different flow coefficients.The hydraulic efficiency at the design flow coefficient was evaluated with variation of the geometric variables,i.e.,the area of the discharge and length of the vane in the diffuser.The result has shown that the hydraulic efficiency of a mixed-flow pump at the design condition is improved by the modification of the geometry.
基金supported by the National Natural Science Foundation of China(Grant No.51176087)
文摘As the geometry of the volute of turbocharger compressor is non-axisymmetric,it causes a distortion at the outlet of the diffuser and influences the upstream components.A distortion model in which a pressure distortion was applied as outlet boundary condition was established to simulate the distortion induced by the volute.It turned out to be sufficient to impose a circumferentially asymmetric pressure distribution at the outlet of the diffuser to replace the volute.Based on the distortion model which was verified,the influence of the amplitude of the distortion on the performance of centrifugal compressor was studied in detail.The results show that the distortion severely harms aerodynamic stability of the investigated compressor.The larger the amplitude of the distortion,the worse the performance of the compressor.The distortion induced by asymmetric volute propagates to upstream components and causes local flow separation at part of diffuser and impeller,and then causes the compressor surge.When the amplitude of the volute distortion is 10%,the stable flow range of the centrifugal compressor decreases to near zero.To authors’knowledge,the relationship between the compressor performance and distortion amplitude is first obtained quantitatively,which provides evidence to improve the performance of turbocharger compressor by decreasing the distortion induced by asymmetric volute.
基金国家自然科学基金资助项目(51305477)Part of the work was carried out under the Collaborative Research Project of the Institute of Fluid Science+1 种基金Tohoku UniversityJapan
基金National Natural Science Foundation of China(No.51776155)
文摘Enhancing stall margin has a great importance for the development of turbo compressors. The application of circumferential grooved casing treatment(CGCT) is a useful method of increasing the stable operating range of the compressor, and the effectiveness of this kind of casing treatment have been proved by numerous experiments. In this paper, a single circumferential casing groove is placed along the shroud side of the vaned diffuser. To clarify the effect of circumferential groove on the centrifugal compressor stability and corresponding flow mechanism, numerical investigations with different radial location, axial depth and radial width were carried out to compare the results. The computational fluid dynamics(CFD) analyses results show that the centrifugal compressor with a single circumferential groove in diffuser passage can extend stable operating range while the efficiency over the whole operating range decreases a little. Efforts were made to study blade level flow mechanisms to determine how the circumferential groove impacts the compressor's stall margin(SM) and performance. Some comparisons of the flow features with different parameter of grooved casing treatment are performed, and the results indicate that the low energy flow in the tip clearance is sucked into the groove and the area of the low energy fluid region shrinks, which helps to improve the stall margin of the centrifugal compressor. The numerical results showed that a combination of position,width and depth of circumferential groove will maximize stall margin improvement(SMI) of the centrifugal compressor.
