Abstract: The sensitivity partial derivatives of doublet strength density with respect to the parameters of wing planfomi(bi-direction perturbation) which are needed to build the general senaitivity equations can be calculated with analytic method based on the intemal Dirichlet prob-leni fonnufation and analytical differentiation cascaded on singular integral8,and then the solu-tion of doublct strength distribution is generated for any perturbed wing planform by linear extrapolation.Thus the pressure distrlbuti on,lift and pitehing moment coefflcients are deter-mined very rapidly.The comparison between the calculated results of the present perturbation panel method and the corresponding lower-order panel method shows that the present algorithm is of fine accuracy and can substantially reduce computing cost required(CPU time req uired for perturbation extrapolation is two orders of magnitude less than that of the corresponding lower-order panel method).

Key words: panel method, perturbation, wing planforms, Dirichlet problem