Comparison of Full-Potential Propagation-Code Computations with the F-5E "Shaped Sonic Boom Experiment" Program

Abstract

The paper addresses the capability of the newlydeveloped full-potential propagation code for predicting the sonic-boom ground signature of the modified F-5E aircraft used in the F-5 “Shaped Sonic Boom Experiment” (SSBE) Program. In the sonic boom computation, the near-field domain is calculated using an Euler solver and the far-field domain is calculated using the full-potential propagation code. At the interface plane between the Euler and the full-potential domains, the velocity components of the Euler solution are transformed into a velocity potential that is used for the initial condition of the full potential solver. Starting with this interface solution the conservative form of the full-potential equation is obtained using a space-marching, upwind scheme. This scheme is augmented by a main block/subblock technique which facilitates the treatment of the varying speed of sound with altitude. Grid adaptation and shock fitting have been applied to the main blocks and sub-blocks of the propagation code. The computational results include three applications. The first application is that of the Susan-Cliff wing-body configuration, where the predicted computational results are successfully compared with the experimental data for mid-field domain. The second application is that of an F-5 aircraft with hypothetical atmospheric conditions. The third application is that of the modified F-5E flight 15, which was conducted on January 13, 2004.