Numerical Simulation of Transonic Flow over Wing-Mounted Twin-Engine Transport Aircraft

Abstract

A numerical method has been developed for computing the e owe eld around advanced transport aircraft with wing-mounted nacelles. The method is based on a multiblock point-matched grid-generation approach combined with zonal solving strategy for complex e owe eld. In this study the e owe eld is divided into a number of nonoverlapped blocks by a cutout technique. H-type grids are generated independently in each block using an elliptic grid-generation method, in which the control of the grid quality is accomplished by the forcing-function technique of Hilgenstock. The e owe eld is simulated by solving the Euler equations. An explicit three-stage Runge ‐Kutta algorithm based on the Jameson’ s e nite volume scheme for the Euler equations has been developed that is applied to the multiregion H-type grids. The present method has been applied to isolated powered engine nacelles and complex transport aircrafts consisting of low-wing/fuselage with wing-mounted pylon/nacelles. On the wing surfaces the viscous effects are simulated by the employment of the viscous/inviscid interaction (VII) technique of two-dimensional strip boundary layer. In this study the boundary-layer program uses an integral method to calculate turbulent boundary layers. With the concept of an equivalent inviscid e ow, the model of blowing velocity is employed in the VII technique. The effect of the boundary layeron the outer inviscid e ow is represented through a transpiration boundaryconditionderived from theboundary-layerparameters.Themain benee tofthistreatment isthatthegridisgeneratedonlyonceinoverallcomputingprocedure.Computationalresultsandcomparisonswith experimental data are presented. The good agreement indicates that the present method is effective in predicting the e ows about powered engine nacelles and/or complex transport aircrafts.