Numerical Study Of The Influence Of Spherical Dimple On The Aerodynamic Performance Of Transonic Sectorial Compressor Cascade

With the rapid development of modern aviation industry,higher performance indicators have been proposed for aero engines.Compressor as the core component of aero engine,it is necessary to improve the higher pressure ratio and efficiency.The study of compressor cascades is particularly important as a key to improving compressor performance.From the perspective of being close to reality,choosing the mainstream transonic blade type can better keep the prospective of scientific research.Studies have shown that the use of dimple control technologies such as transonic diffuser cascades and reasonable placement of pits on the blade surface can effectively suppress the flow of the wall and the surface layer and achieve the drag reduction effect,which is an effective way to improve the aerodynamic performance of the compressor oneIn this paper,the transonic DMU37 static blade tip is used as the airfoil,and the numerical simulation method is used to investigate the geometrical factors of the spherical pit on the transonic sectorial pressure expansion from the aspects of total pressure loss,limiting streamline,blade surface static pressure distribution and turbulent kinetic energy.The mechanism of aerodynamic performance and loss characteristics of the cascade is used to further analyze the causes of drag reduction.This article analyzes the following aspects:First,the three-dimensional modeling software was used to design the sectorial cascade flow channel,and the feasibility of the numerical method was verified.Explore the flow characteristics and loss mechanism of the sectorial diffuser cascade,and the aerodynamic performance under variable impulse angle.It was found that due to the radial centrifugal force and the circumferential force,the annular diffuser cascades flow up and down asymmetrically,and the lower angle zone is more separated,and the increase of the angle of attack will exacerbate this phenomenon.In the near-stall state,'angular zone separation dominates.Then,based on the prototype cascade,reasonable selection of pit related parameters,including pit spacing and pit position,was performed to perform numerical calculation of the pit cascade.Due to the intervention of the pits on the leaf surface,the flow becomes complicated.The pits can effectively improve the high-loss areas in the corner area and the profile loss,but the total pressure loss at the outlet section increases slightly.From the point of view of changing the pit spacing,the effect of each spacing is complex,and the spacing of 4mm is relatively good.On this basis,choosing three rows of pits near the leading edge can effectively reduce the wake loss at the median diameter of 2.17%.The pit can effectively increase the turbulent kinetic energy and improve the load capacity of the airfoil.However,the excessively high turbulent kinetic energy will cause the flow in the boundary layer to turn early,further deteriorate the mixing with the mainstream,and increase the total loss.Finally,the original cascade and the cascade of the best pit scheme are analyzed under variable conditions.Through the analysis of the loss characteristics of the exit section and the limit streamline of the variable operating conditions,it is found that the pit can effectively reduce its blade loss,but the total loss slightly increases,further confirming the value of the pit for drag reduction.