基于当地流活塞理论的气动弹性计算方法研究

NUMERICAL METHOD OF AEROELASTICITY BASED ON LOCAL PISTON THEORY

发展了一种高效、高精度的超音速、高超音速非定常气动力计算方法——基于定常CFD技术的当地流活塞理论.运用当地流活塞理论计算非定常气动力,耦合结构运动方程,实现超音速、高超音速气动弹性的时域模拟.运用这种方法计算了一系列非定常气动力算例和颤振算例,并和原始活塞理论、非定常Euler方程结果作了比较.由于局部地使用活塞理论假设,这种方法大大地克服了原始活塞理论对飞行马赫数、翼型厚度和飞行迎角的限制.与非定常Euler方程方法相比,当地流活塞理论的效率很高.

Existing piston theory for supersonic flow can only deal with thin supersonic wing with sharp leading edge at small angles of attack. The unsteady CFD technology basing on Euler/N-S equations can solve the unsteady aerodynamic loads precisely, but it often needs much computational time even just for a simple 3D shapes. This paper presents a local piston theory for calculating supersonic unsteady aerodynamic loads due to structural motion or deformation. A steady flow solution is first obtained by an Euler method. The piston theory is applied locally at each point on the airfoil surface on top of the mean steady flow field to obtain the unsteady pressure perturbations caused by the deviation of the airfoil surface from its mean location. Computations by this method are performed for a number of unsteady flows and flutter results. The results are compared with those by the classical piston theory and fully unsteady Euler calculations. Because the piston theory is used only locally, this method greatly reduces the limitations of the classical piston theory on flight Mach number, airfoil thickness, and angles of attack. Compared to the fully unsteady Euler method, the local-piston theory method is very efficient. Only one steady-state solution is needed for the time-domain unsteady calculations.