An improved algorithm for velocity field of general configurations ispresentd for low-order panel method based on the internal Dirichlet boundary condi-tion. A direct calculating method for the velocity distribution b...An improved algorithm for velocity field of general configurations ispresentd for low-order panel method based on the internal Dirichlet boundary condi-tion. A direct calculating method for the velocity distribution by means of a limit pro-cess combining with analytic evaluation of higher-order singular integrals instead of theconventional method of doublet strength gradient is devised in order to avoid the diffi-culty of edge extrapolation of doublet strength. The problem of substantialunderpredictions of the induced drag coefficient obtained from the VSAERO analysisdisappears for the present improved algorithm. Illustrative calculations for several testcases such as swept back wing, swept forward wing and wing-body combination showthat the accuracy of results may be improved and is competitive with high-order panelmethod. In addition, the present direct integral method can be used to evaluate the ve-locity distribution for external flow field correctly, where the method of gradient cannot be used at all.展开更多
文摘An improved algorithm for velocity field of general configurations ispresentd for low-order panel method based on the internal Dirichlet boundary condi-tion. A direct calculating method for the velocity distribution by means of a limit pro-cess combining with analytic evaluation of higher-order singular integrals instead of theconventional method of doublet strength gradient is devised in order to avoid the diffi-culty of edge extrapolation of doublet strength. The problem of substantialunderpredictions of the induced drag coefficient obtained from the VSAERO analysisdisappears for the present improved algorithm. Illustrative calculations for several testcases such as swept back wing, swept forward wing and wing-body combination showthat the accuracy of results may be improved and is competitive with high-order panelmethod. In addition, the present direct integral method can be used to evaluate the ve-locity distribution for external flow field correctly, where the method of gradient cannot be used at all.
