Aerodynamic Losses And Aerodynamic Noise Of Sawtooth Trailing Edge Blades Of Aero Compressor

The efficiency and noise of aero-engine have always been the focus of attention.Compressor is an important component of aero-engine.Flow loss in the compressor will reduce its efficiency.The efficiency of the compressor directly reflects the loss of air flowing through the compressor.The trailing edge structure of compressor blade has a great influence on its efficiency and noise.The triangular trailing edge sawtooth structure has attracted special attention.For this reason,a typical triangular sawtooth model of the trailing edge of an axial compressor blade is established,and the three-dimensional turbulent flow field in the wake region of the blade with sawtooth trailing edge is simulated by Fluent software.The effects of triangular sawtooth trailing edge blades and non-sawtooth trailing edge blades with different structures on compressor aerodynamic loss and noise were compared and analyzed.The flow loss mechanism and noise reduction mechanism of sawtooth trailing edge blades were analyzed.This paper can provide data support and theoretical basis for optimum design of compressor with high performance,high efficiency and low noise.It has important significance for aerodynamic design and acoustic design of compressor.The main research work is as follows:(1)Firstly,the NACA651210 A compressor blade of an aeroengine is selected as the reference blade and defined as H/W=0.Two typical triangular sawtooth trailing edge blade models are designed,which are H/W=1 and 2,respectively.Then,the meshes of the three models H/W=0,1 and 2 are refined and the corresponding boundary conditions are set up,and the numerical simulation method is given.Large eddy simulation method and the selection of time step are introduced.Finally,the correctness of simulation results and experimental data are compared and verified.(2)In order to investigate the effect of sawtooth trailing edge blade on compressor aerodynamic loss and noise,three models H/W=0,1 and 2 were simulated.The results show that: 1)As for the effect of sawtooth trailing edge blade on compressor aerodynamic loss,with the increase of sawtooth height-width ratio H/W,the velocity in the blade wake region increases.The total pressure loss is reduced by increasing the velocity loss and decreasing the velocity loss.Then the total pressure loss is compared with that of the blade without sawtooth trailing edge.Compared with the blade without sawtooth trailing edge H/W=0,the two blades with sawtooth trailing edge H/W=1 and 2 both play an important role in reducing the total pressure loss,and the total pressure loss coefficients of both blades ? are 0.086;2)Because of the sawtooth structure,the six kinds of sawtooth trailing edge blades(H/W=1,1.2,1.4,1.6,1.8,2)all played a role in reducing the monotone spike noise,of which the sawtooth trailing edge blades H/W=1.2,H/W=1.4 had the smallest noise,and the monotone spike noise of both blades was 65 dB,which reduced the monotone spike noise of 45 dB.(3)On the basis of studying the effect of sawtooth blade on compressor aerodynamic loss and aerodynamic noise,four kinds of sawtooth blade models were added and refined modeling was carried out to explore the structure of sawtooth blade with the least aerodynamic loss and the least noise.The following conclusions were obtained by numerical simulation: 1)Sawtooth blade with sawtooth blade.With the increase of tooth height-width ratio H/W,the velocity loss decreases gradually.The velocity loss of sawtooth trailing edge blade H/W=2 is the smallest,which is 23.88 m/s.The total pressure loss of sawtooth trailing edge blade H/W=1.2 is the smallest,and the coefficient of total pressure loss ? is 0.083;2)Because of the sawtooth structure,the six kinds of sawtooth trailing edge blades(H/W=1,1.2,1.4,1.6,1.8,2)have the smallest total pressure loss.Both of them played a role in reducing monotone spike noise.The noise of sawtooth trailing edge blade H/W=1.2 and H/W=1.4 was the smallest.The monotone spike noise of both blades was 65 dB,and the monotone spike noise of 45 dB was reduced.(4)For the sawtooth trailing edge blade H/W=2 velocity loss is the smallest,and the sawtooth trailing edge blade H/W=1.2,H/W=1.4 noise is the smallest phenomenon,it is necessary to analyze its mechanism.Through the analysis of aerodynamic loss mechanism and noise reduction mechanism,we can see that: 1)the sawtooth trailing edge blade on the aerodynamic loss mechanism,because of the existence of blade trailing edge sawtooth structure.In order to reduce the aerodynamic loss,the flow can flow from the blade pressure surface to the suction surface through the sawtooth slot,so as to control the flow loss.With the increase of the sawtooth height-width ratio H/W,the flow from the pressure surface to the suction surface through the sawtooth slot becomes more and more frequent.When the blade H/W=2,the flow is the most;2)For the sawtooth trailing edge blade,the reduction of the single-tone spike noise is due to the breakdown of the blade spanwise vortices,from large-scale vortices to small-scale vortices.According to the Vortex-Acoustic Equation of Powell,the reduction of the vorticity is beneficial to the reduction of the noise,compared with the blade without sawtooth trailing edge,the sawtooth blade Tooth trailing edge blades have the effect of reducing the single-tone peak noise.With the increase of sawtooth height-width ratio H/W of sawtooth trailing edge blades,H/W=1.2 and H/W=1.4 direction vortex breaking is more thorough,so the two kinds of sawtooth blades have more significant noise reduction effect.(5)From the above study,it can be concluded that the sawtooth height-width ratio H/W of the blade with sawtooth trailing edge should be between 1.2 and 1.4 in order to obtain the optimal design scheme of the compressor with high performance,high efficiency and low noise,considering the performance indexes such as total pressure loss,velocity loss and single-tone spike noise.