USE OF POTENTIAL FLOW THEORY TO EVALUATE SUBSONIC INLET DATA FROM A SIMULATOR-POWERED NACELLE AT CRUISE CONDITIONS

摘要

Incompressible potential flow theory corrected for compressibility effects, using the Lieblein-Stockman compressibility correction, was used to predict surface and flow field static pressures for a subsonic inlet at cruise conditions. The calculated internal and external surface static pressures were in good agreement with data at most conditions. The analysis was used to de¬termine the capture stream-tube location and static-pressure distribution. Additive drag coef¬ficients obtained from these results were consistently higher than those obtained using one-dimensional compressible flow theory. Increasing the distance between the inlet and boattail increased the cowl drag force. The effect of the boundary layer on internal and external sur¬face static-pressure distributions was small at the design cruise condition. The analytical results may be used as an aid to data reduction and for predicting inlet mass flow, stagantion point location, and inlet additive drag.