Abstract:

According to the assumption of high Mach numbers the secondorder equation for unsteady flow reduces to a form analogous to that for steady flow. As an approximation, a particular solution is derived from the assumption of local two-dimensionality instead of the approximate three-dimensional particular solution.In treatment of the unsteady problem for delta wings with low, aspect ratio and supersonic leading edges, the non-linear pressure relation and the modified reference flow parameters are adopted to take the effect of mean angles of attack into account. Analytical expressions are obtained for the first order expansion of the unsteady velocity potential. They conduce to simplifying the calculation of stability derivatives to a great extent.Stability derivatives for flat .plate, double-wedge or biconvex delta wings oscillating at low frequencies are given respectively. Since the corresponding experimental data are unavailable, the obtained results, are merely compared with those of Hui's flat plate1"4'1, and both results are in good agreement.