Engine power simulation for transonic flow-through nacelles

The results of a numerical simulation of engine-power effects on the transonic flow through a nacelle are presented. The model developed requires only minor modifications to conventional airfoil codes and is suitable for preliminary design applications. A nacelle with an external shape equivalent to a 10-percent-thick symmetric parabolic-arc airfoil and a circular-cylindrical interior (chord-to-diameter ratio = 2) was investigated at Mach 0.92 and 0.98 for N = O (unpowered) and N = 3 (powered), using a 60 x 60 mesh. The analytical approach, model assumptions, and numerical method are discussed. The Cp plots of the results are found to reflect the basic characteristics of powered flows, including the virtual disappearance of the external shock. The extension of this simplified approach to 3D flows (in nonaxisymmetric nacelles) is considered.