The outlet flow fields of a low-speed repeating-stage compressor with bowed stator stages are measured with five-hole probe under the near stall condition when the rotor/stator axial gap varies. The performances of th...The outlet flow fields of a low-speed repeating-stage compressor with bowed stator stages are measured with five-hole probe under the near stall condition when the rotor/stator axial gap varies. The performances of the straight stator stages are investigated and compared to those of the bowed stator stages. The results show that using bowed stator stages could alleviate the flow separation at both upper and low corners of the suction surface and the endwalls, and decrease the losses along the flow passage as well as the outlet flow angle. As the rotor/stator axial gap decreases, although the diffusion capacity of the compressor increases obviously, the outlet flow field in the straight stator stages deteriorates quickly. By contrast, little changes occur in the bowed stator stages, indicating that as the rotor/stator axial gap decreases, improved performance is achieved in the bowed stator stages.展开更多
An extensive numerical investigation is conducted to characterize the flow separation control in a transonic compressor cascade with a porous bleed.The bleed holes are arranged on the suction surface in a single row,t...An extensive numerical investigation is conducted to characterize the flow separation control in a transonic compressor cascade with a porous bleed.The bleed holes are arranged on the suction surface in a single row,two staggered rows and three staggered rows.For each bleed scheme,five bleed pressure ratios are examined at an inlet Mach number of 1.0.The results indicate that the aerodynamic performance of the cascade is significantly improved by the porous bleed.For the single-row scheme,the maximum reduction in total pressure losses is 57%.For the two-staggered-row and three-staggered-row schemes,there is an optimal bleed pressure ratio of 1.0,and the maximum reductions in total pressure loss are 68% and 75%,respectively.The low loss in the cascade is due to the well-controlled boundary layer.The new local supersonic region created by the bleed hole is the key reason for the improved boundary layer.The vortex induced by side bleeding provides another mechanism for delaying flow separation.Increasing the bleed holes could create multiple local supersonic regions,which reduce the range of the adverse pressure gradient that the boundary layer needs to withstand.This is the reason why cascades with more bleed holes perform better.展开更多
For a transonic axial-flow compressor, the numerical simulations, verified against experimental data, were used to study the inherent correlation between the evolutionary process of the vortex structures and the flow ...For a transonic axial-flow compressor, the numerical simulations, verified against experimental data, were used to study the inherent correlation between the evolutionary process of the vortex structures and the flow loss in a compressor stator passage during the throttling process. The flow loss was divided accurately and quantitatively, based on the evolutionary process of the vortex structures. According to the position of the singular points of the vortex structures, the influence of the evolution of the vortex structures on the generation and development of the flow loss was analyzed on a microscale scale. Thereafter, this paper provided the vortex dynamic mechanism of the flow loss, which was important to enrich the theoretical system of the flow field in the compressor. The results show that: the flow loss at the top of the stator tip is caused by the low-energy fluid clusters, which are transported and accumulated by the vortices from the endwall; the transport effect of the pressure separation vortex at the upper half-height only migrates the position of the flow losses, but there is new flow loss generated by its shear action to the endwall. The dominant flow loss during the throttling process concentrates upon the closed separation bubble around the middle of the suction side of the stator.展开更多
This paper is focused on the experimental study of the effects of stator clocking on the performance of a low-speed repeating stage axial compressor with compound-lean stators as well as the one with conventional stat...This paper is focused on the experimental study of the effects of stator clocking on the performance of a low-speed repeating stage axial compressor with compound-lean stators as well as the one with conventional stators （the baseline） for comparison. The experimental results show that as the clocking positions vary, the upstream stator wake enters the following passage at different circumferential positions, and then mixes with the local fluid in the following passage. This is the main reason for the variation of the compressor performance resulted from the stator clocking effects. The variation of the compressor performance due to the clocking effect is less pronounced for the compressor with compound-lean stators than with the baseline. At a certain clocking position, the efficiency of the compressor with compound-lean stators is increased in comparison with that of the baseline, especially on small mass flow rate conditions, e.g., 0.7% at design condition and 3.5% at near-surge condition in this case. The maximum 1.22% and the minimum 0.07% increases in efficiency on design condition are obtained through the combined effects of the stator compound-lean and the stator clocking in this case.展开更多
This article proposes a tandem cascade constructed to tackle the thorny problem of designing the high-loaded stator with a supersonic inflow and a large turning angle. The front cascade adopts a supersonic profile to ...This article proposes a tandem cascade constructed to tackle the thorny problem of designing the high-loaded stator with a supersonic inflow and a large turning angle. The front cascade adopts a supersonic profile to reduce the shock wave intensity turning the flow into subsonic,while the rear cascade adopts a subsonic profile with a large camber offering the flow a large turning angle. It is disclosed that the losses would be minimized if the leading edge of the rear cas- cade lies close to the pressure side of the front cascade at a distance of 20% pitch in pitch-wise direction without either axial spacing or overlapping in axial direction. The 2D numerical test results show that,with the inflow Mach number of 1.25 and the turning angle of 52° ,the total pressure loss coefficient of the tandem cascade reaches 0. 106 ,and the diffusion factor 0. 745. Finally,this article has designed and simulated a high-loaded fan stage with the proposed tandem stator,which has the pressure ratio of 3.15 and the efficiency of 86.32% at the rotor tip speed of 495.32 m/s.展开更多
Numerical investigation of the unsteady flow variability driven by rotorstator interaction in a transonic axial compressor is performed. Two models with close and far axial gap between rotor and stator rows are studie...Numerical investigation of the unsteady flow variability driven by rotorstator interaction in a transonic axial compressor is performed. Two models with close and far axial gap between rotor and stator rows are studied in the simulation. Particular attention is attached to the analysis of mechanisms involved in driving rotor wake oscillation, rotor wake skewing and flow angle fluctuation at rotor exit. The results show that smaller axial gap is favorable to enhance the interaction in the region between two adjacent rows, and the fluctuation of the static pressure difference between two sides of rotor wake is improved by potential field from down stator, which is the driving force for rotor wake oscillation. The interaction between rotor and stator is weakened by increasing axial distance, rotor wake shifts to suction side of rotor blade with 5%-10% of rotor pitch, the absolute value of flow angle at rotor exit is less than that in the case of close interspace for every time step, and the fluctuation amplitude is also decreased.展开更多
基金National Natural Science Foundation of China (50646021)Chinese Specialized Research Fund for the Doctoral Pro-gram of Higher Education (20060213007)
文摘The outlet flow fields of a low-speed repeating-stage compressor with bowed stator stages are measured with five-hole probe under the near stall condition when the rotor/stator axial gap varies. The performances of the straight stator stages are investigated and compared to those of the bowed stator stages. The results show that using bowed stator stages could alleviate the flow separation at both upper and low corners of the suction surface and the endwalls, and decrease the losses along the flow passage as well as the outlet flow angle. As the rotor/stator axial gap decreases, although the diffusion capacity of the compressor increases obviously, the outlet flow field in the straight stator stages deteriorates quickly. By contrast, little changes occur in the bowed stator stages, indicating that as the rotor/stator axial gap decreases, improved performance is achieved in the bowed stator stages.
基金the financial support provided by the National Science and Technology Major Project (2017-Ⅱ-0007-0021)。
文摘An extensive numerical investigation is conducted to characterize the flow separation control in a transonic compressor cascade with a porous bleed.The bleed holes are arranged on the suction surface in a single row,two staggered rows and three staggered rows.For each bleed scheme,five bleed pressure ratios are examined at an inlet Mach number of 1.0.The results indicate that the aerodynamic performance of the cascade is significantly improved by the porous bleed.For the single-row scheme,the maximum reduction in total pressure losses is 57%.For the two-staggered-row and three-staggered-row schemes,there is an optimal bleed pressure ratio of 1.0,and the maximum reductions in total pressure loss are 68% and 75%,respectively.The low loss in the cascade is due to the well-controlled boundary layer.The new local supersonic region created by the bleed hole is the key reason for the improved boundary layer.The vortex induced by side bleeding provides another mechanism for delaying flow separation.Increasing the bleed holes could create multiple local supersonic regions,which reduce the range of the adverse pressure gradient that the boundary layer needs to withstand.This is the reason why cascades with more bleed holes perform better.
基金supported by a project funded by the China Postdoctoral Science Foundation(Grant No.2017M621268)the National Natural Science Foundation of China(Grant Nos.51436002,51506020,and 51706051)
文摘For a transonic axial-flow compressor, the numerical simulations, verified against experimental data, were used to study the inherent correlation between the evolutionary process of the vortex structures and the flow loss in a compressor stator passage during the throttling process. The flow loss was divided accurately and quantitatively, based on the evolutionary process of the vortex structures. According to the position of the singular points of the vortex structures, the influence of the evolution of the vortex structures on the generation and development of the flow loss was analyzed on a microscale scale. Thereafter, this paper provided the vortex dynamic mechanism of the flow loss, which was important to enrich the theoretical system of the flow field in the compressor. The results show that: the flow loss at the top of the stator tip is caused by the low-energy fluid clusters, which are transported and accumulated by the vortices from the endwall; the transport effect of the pressure separation vortex at the upper half-height only migrates the position of the flow losses, but there is new flow loss generated by its shear action to the endwall. The dominant flow loss during the throttling process concentrates upon the closed separation bubble around the middle of the suction side of the stator.
基金National Natural Science Foundation of China (50236020)
文摘This paper is focused on the experimental study of the effects of stator clocking on the performance of a low-speed repeating stage axial compressor with compound-lean stators as well as the one with conventional stators （the baseline） for comparison. The experimental results show that as the clocking positions vary, the upstream stator wake enters the following passage at different circumferential positions, and then mixes with the local fluid in the following passage. This is the main reason for the variation of the compressor performance resulted from the stator clocking effects. The variation of the compressor performance due to the clocking effect is less pronounced for the compressor with compound-lean stators than with the baseline. At a certain clocking position, the efficiency of the compressor with compound-lean stators is increased in comparison with that of the baseline, especially on small mass flow rate conditions, e.g., 0.7% at design condition and 3.5% at near-surge condition in this case. The maximum 1.22% and the minimum 0.07% increases in efficiency on design condition are obtained through the combined effects of the stator compound-lean and the stator clocking in this case.
基金National Natural Science Foundation of China(10577002)Innovation Foundation of BUAA for PhD Graduates
文摘This article proposes a tandem cascade constructed to tackle the thorny problem of designing the high-loaded stator with a supersonic inflow and a large turning angle. The front cascade adopts a supersonic profile to reduce the shock wave intensity turning the flow into subsonic,while the rear cascade adopts a subsonic profile with a large camber offering the flow a large turning angle. It is disclosed that the losses would be minimized if the leading edge of the rear cas- cade lies close to the pressure side of the front cascade at a distance of 20% pitch in pitch-wise direction without either axial spacing or overlapping in axial direction. The 2D numerical test results show that,with the inflow Mach number of 1.25 and the turning angle of 52° ,the total pressure loss coefficient of the tandem cascade reaches 0. 106 ,and the diffusion factor 0. 745. Finally,this article has designed and simulated a high-loaded fan stage with the proposed tandem stator,which has the pressure ratio of 3.15 and the efficiency of 86.32% at the rotor tip speed of 495.32 m/s.
基金National Natural Science Foundation of China (51176013)Ph.D. Programs Foundation of Ministry of Education of China (20091101110014)National High-tech Research and Development Program of China (2007AA050502)
文摘Numerical investigation of the unsteady flow variability driven by rotorstator interaction in a transonic axial compressor is performed. Two models with close and far axial gap between rotor and stator rows are studied in the simulation. Particular attention is attached to the analysis of mechanisms involved in driving rotor wake oscillation, rotor wake skewing and flow angle fluctuation at rotor exit. The results show that smaller axial gap is favorable to enhance the interaction in the region between two adjacent rows, and the fluctuation of the static pressure difference between two sides of rotor wake is improved by potential field from down stator, which is the driving force for rotor wake oscillation. The interaction between rotor and stator is weakened by increasing axial distance, rotor wake shifts to suction side of rotor blade with 5%-10% of rotor pitch, the absolute value of flow angle at rotor exit is less than that in the case of close interspace for every time step, and the fluctuation amplitude is also decreased.
