Numerical Study on Variation in Drag Difference by Adding Annular Plug into Flow-Through Nacelle with Integrated Configuration

Abstract

Spillage drag varies with capture area ratio (CAR). However, it is not easy to investigate it experimentally since the shape inside a flow-through nacelle of a testing model needs to be changed. Numerical analyses using computational grids of annular plugs inside the flow-through nacelle were performed to clarify the change in the spillage drag for the flow-through nacelle of a business-jet-geometry testing model. As a result, differences in CAR and the axial component of the aerodynamic coefficient were observed by adding the plug. It was shown that a significant change in CAR is only apparent if the plug is squeezed significantly. However, a large squeeze can cause flow separation inside the nacelle and adversely affect the aerodynamic coefficient. Finally, we showed a range where the difference was little affected by parameters other than the CAR and the preliminary result of the correction of the spillage drag using the CFD data.