Numerical Study On The Effect Of Boundary Layer Suction On A Transonic Sectorial Compressor Cascade

With the rapid development of aircraft industry in the 21st century,gas turbine engines occupy a pivotal position in the aerodynamics industry.As one of the core components of the compressor,the increase of pressure ratio is quite urgent at this stage.Increasing the pressure ratio is bound to bring about a high load,and the high load makes the cascade of the large-angle corner easier to separate at the suction surface.Once the separation range is large enough,the flow path will be blocked then causes stall or surge.The occurrence of severe separation can cause heavy damage to the compressor.In this paper,the numerical simulation is used to analyze the flow field structure of the transonic sectorial cascade under near-stall conditions.After analyzing the formation mechanism of the corner separation under the near stall condition and verifying the effect of the suction on the cascade of the compressor stage,the boundary layer suction is applied to the transonic diffuser cascade with inlet guide vanes,and the solution includes:streamwise groove suction on upper endwall,streamwise hole suction on upper endwall,radial groove suction on suction surface and both upper endwall and suction surface combination groove;After the numerical simulation,the mechanism of the suction is analyzed by means of the total pressure loss coefficient contour,the limiting streamline and the distribution of pressure coefficient,the analysis aims to find out the effect of suction on the loss of the transonic cascade with guide vanes and the optimal position for suction.First,the upper half of the prototype cascade has a large range of comer separation.The formation of the eorner zone is mainly caused by the mixing and secondary flow of the fluid in the boundary layer between the endwall and the suction surface of the blade,which cause the flow from the pressure surface to deflect and return back to the suction surface at the trailing edge,thereby generating a large-scale corner separation.In order to obtain a better suction effect,it is necessary to analyze the position of the separation starting point and the separation vortex core,and then set the position of the suction groove near the separation starting point and near the separation vortex core.There is an optimal suction flow,the overall performance improvement will be reduced if it is too large or too small.Secondly,using the upper streamwise groove suction can effectively weaken the comer separation,especially when the groove is disposed at a position near the separation starting point(EWI),the effect is optimal with the starting point sucked out and topological structure of the upper endwall near the inlet simplified,and the total pressure loss of the cascade is reduced by 15.82%,and the static pressure ratio is increased by 4.58%.The upper streamwise holes are more suitable for practical application,and it also has a significant effect on weakening corner separation,the overall total pressure loss coefficient of the EWI scheme is reduced by 12.24%compared with the prototype;When the suction radial slot on the suction surface is set near the separation vortex core(SS3),its effect is better than that on the other position of suction surface in the same flow rate,the slot weakens the separation vortex and inhibits the development of the separation subsequent vortex,thus showing better effect of controlling corner separation.The total pressure loss of the cascade is reduced by 16.68%,and the static pressure ratio is increased by 4.73%.However,since the lateral secondary flow in the flow path is enhanced by suction,the passage vortex is correspondingly strengthened,but it has little effect on the overall improvement effect.Thirdly,the combination groove suction simultaneously weakens the low-energy fluid in the boundary layer of the endwall and the suction surface,which combines the advantages of the endwall suction and suction surface suction,the combination groove can simultaneously absorb the boundary layer of both endwall and suction surface,then reduce the mutual blending and thickness of boundary layer,thereby achieving the purpose of weakening the comer separation and decreasing the loss.