Modified Version of LTRAN2: A Calculation Method for Inviscid Transonic Flow About Thin Airfoils in Moderately Slow Unsteady Motion

摘要

A method for strictly slow unsteady motions is modified by including extra unsteady terms in the boundary conditions. The unsteady transonic small perturbation equation and the airfoil, wake and far field boundary conditions are derived heuristically. A radiation condition on the far field boundary which accommodates outgoing disturbances only is presented. Analysis shows that the infinite physical domain surrounding the airfoil can not be mapped onto a finite computational domain. Numerical experiments on an airfoil oscillating in pitch at reduced frequencies 0.05 and 0.1 for a freestream Mach number = 0.85, and zero angle of attack show that radiation condition can reduce the computational domain and the number of grid points.