Supersonic Nozzle Optimization Design

With restart global algorithm and Gaussian process model,supersonic nozzle contour optimization is investigated to improve the flow quality in the test section of a continuous transonic wind tunnel in China Aerodynamic Research and Development Center.According to the experimental results in the continuous transonic wind tunnel,the optimization problem was defined and the CFD results are verified.The crowding distance notation is introduced to form a restart mechanism,which leads to a highly efficient global algorithm.The relationship between design parameters and aerodynamic performances is modeled with Gaussian process model,which is used in optimization as a surrogate for the real evaluation procedure to reduce the number of evaluation.Two kinds of nozzle optimization methods are proposed: the first one,depending on the potential flow contour of Sivells,the boundary layer correction angle and the test section wall expansion angle are chosen as the designing variables;the second one,cubic spline curves with the optimal interpolating points distribution scheme are used to fit the nozzle contour and the heights of those interpolating points are chosen as the designing variables.The optimization framework can generate a supersonic nozzle contour with better flow quality and more accurate efficiently,the root mean square deviation of Mach number in model area falls from 0.012 to0.001,and axial gradient of Mach number falls from 0.049 to 0.