Aerodynamic Admittance Function using Impulse Response Function Approach

Abstract

An explanation described here is how the aerodynamic admittance function(AAF) is to derive by means of impulse response function(IMF) which is modified for two peaks (movement-induced and Karman Vortex-induced) intending to be able to deal with the response condition under higher reduced wind speed. By using the analogy of the Sears function and the flutter derivatives, the relationship between the aerodynamic derivatives(AD) and aerodynamic admittance function is clarified. The equivalent Sears function(ESF) is obtained through Fourier transform of IMF incorporate with some shape parameters. After AD has been approximated, the corresponding AAF, which is the square value of ESF, is achieved. This paper includes the verification that the AAF of thin airfoil estimated applying the formulation is found to agree well with thin airfoil Sears function proposed by Holmes and Liepmann.