基于流场/声爆耦合伴随方程的超声速公务机声爆优化

Based on the PMB3D solver for large-scale parallel structured CFD grid and the PADJ3D solver for parallel adjoint equation (in-house code), a study of flow/sonic boom coupled adjoint equations is carried out. Firstly, the reliability of the sonic boom calculation for the PMB3D and the reliability of the sonic boom prediction are verified, and the precision of sonic boom signal to the gradient of the near-field input signal is validated. To address the complex extraction of near-field sonic boom signal in multi-block grid, a "sonic boom box" approach is proposed providing cell numbering of near-field sound pressure assembly, grid block numbering, and corresponding process number determination in parallel environment. Then based on the calculated coordinates of sonic boom, the data passed in parallel environment are one-dimensionally sorted, providing input conditions for sonic boom prediction, adjoint equations, and gradient solutions. The Jacobi matrix of linear interpolation is used to transform the gradient information of uniform coordinate system to non-uniform coordinates. Furthermore, the principle of improved interpolation is proposed in accordance to the features of the structural grid, simplifying the variation of the near-field transformation in Jacobi matrix. By recording the assembly unit, the derivative of the sonic boom signal on flow field variable is assembled to the grid cell, and the assembled result is used as the right term for the flow field adjoint equations to obtain the solution of the flow/sonic boom coupled adjoint equations. The level of sonic boom is optimized for small supersonic business jets, and the contours of typical cross-sectional flow field pressure before and after the design are compared and the differences between the two results are analyzed.