Use of Potential Flow Theory to Evaluate Subsonic Inlet Data from a Simulator-powered Nacelle at Cruise ConditionsIncompressible 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 determine the capture stream-tube location and static-pressure distribution. Additive drag coefficients 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 surface 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, stagnation point location, and inlet additive drag. |
Common terms and phrases
additive drag coefficients analysis boundary layer boundary-layer effect calculated capture stream tube Comparison of theoretical compressibility correction compressible flow theory corrected for compressibility cowl drag coefficients cowl drag force cowl external surface cowl pressure distributions cruise conditions Data 180 Theory determined Dimensionless axial location Dinl distributions at free-stream Dmax effects of mass-flow experimental cowl external experimental pressure distributions external cowl external cowl pressure external surface static-pressure ferential angle flow rate flow ratio free-stream Mach 0.75 free-stream Mach number free-stream total pressure incompressible incompressible velocity inlet additive drag inlet and boattail inlet choked inlet drag coefficients inlet highlight inlet mass-flow ratio internal pressure distributions Lewis Research Center maximum nacelle NASA NASA TM number of 0.60 potential flow predict pressure to free-stream ratio and free-stream Ratio of surface shown in figure stagnation point stagnation-point location surface static pressure surface static-pressure distributions theoretical and experimental Turbofan two-dimensional