Optimization Platform And Research On Compressor Cascade Flow

With the gas turbine having higher requirements on the performance indicators of multistage axial compressor such as operating efficiency levels and stable working range, the high aerodynamic performance blade, which is an important part of the high performance compressor, has been extensively concerned by the domestic and foreign researchers for a long time.In order to expand the range of varying duty condition and reduce the total pressure loss,the design platform of automatic optimization for compressor blade is constructed in this passage. In the optimization process, the blade shape,optimize selected variables and the objective function are important factors to build the optimization results. First of all, in order to get parametric blade, selecting the middle section of the last stage of a compressor stator blade as an initial blade, fitting the camber of the blade based on the least squares method and Bezier curve, using the modeling method that the medial camber line distribute with the thickness. This method has certain novelty in the shape of the compressor blades. Secondly,the MATLAB script file template is written to generate grid computing program and change the angle of attack, the mesh of the parametric blade will be created by using NUMECA Autogrid5. Flow field calculation is taken based on the SST turbulence model. After obtaining the flow field calculation, the objective function, which has the basis of a set of predecessors and greatly reduce the amount of calculation and could also match the design requirements,is designed. Finally, flow field calculation has been taken by using ANSYS-CFX and the objective function which can give consideration to the total pressure loss under the working condition and the scope of work has been established. The above models are integrated in the ISIGHT software and the optimization has been taken by using the optimized algorithm in the software. Using object-oriented and modular software development method to design a platform of automatic optimization for compressor blade which apply to engineering appliance.In order to optimize the development of the software platform optimized verification,and use this platform for an optimized airfoil. Based on the completion of the design platform of automatic optimization for compressor blade, the optimized design has been taken by taking the blade profile fitted by the media camber line of a multistage axial-flow compressor last stage stator and CDA blade thickness distribution as the original blade profile. The scope of work of optimized blade profile increased by 30%, and the side working range of positive incidence increased by 50%. To further study on the impact of optimization variables used in the optimization of the airfoil surface flow, these parameters and the airfoil transition relations research will be taken.The transition location always affects the profile loss, in order to study the influence of blade parameters on the transition position .In order to study this with the chord length,setting angle, inlet and outlet flow angle, relative leading edge and trailing edge radius unchanged. The maximum relative thickness,deflection of the thickness distribution of the front and the location of the maximum thickness of blade profile has been changed .Meanwhile the turbulence model is SST, and the transition model is Gamma-Theta.Based on the obtained high performance optimized blade profile, the three-dimensional plane cascade has been made by stacking the optimized blade profile along the leading edge. With the change of the length axis ratio, the conclusion can be gotten: the total pressure loss coefficient decreased when the length axis ratio of elliptical leading edge increased.Finally, there is often a case of flow separation in the three-dimensional blade angle of the end zone, and the flow in the end zone is different with which in the mid-section. In order to obtain a optimized blade which suits the end zone,optimize the end wall profile by using the automatic optimization platform. The optimized blade that used the method of optimizing the end wall profile can decrease the total pressure loss coefficient and expands the off-design working range; meanwhile bending the blade near the end wall has been used, with the conclusion: as the increase of the positive bending angle, the flow separation in the end wall of the blade is improved.