Dynamic inlet distortion predictions using a CFD/distortion synthesis approach

Abstract

A procedure is presented to predict dynamic inlet distortion using a combined CFD and distortion synthesis method. A prediction of the steady state total pressure pattern at the Aerodynamic Interface Plane (AIP) is first obtained using a CFD Navier-Stokes program incorporating a two-equation turbulence model. A corresponding inlet turbulence pattern is obtained from the CFD solution via a correlation linking root mean square (RMS) inlet turbulence to a formulation of several CFD parameters representative of flow turbulence intensity. A distortion synthesis process is then performed using the CFD predicted steady state total pressure and the derived RMS turbulence patterns to yield predictions of the peak dynamic distortion intensity. Computations of inlet lip surface pressures and steady state inlet recoveries are shown to be in excellent agreement with the flight test data and validate the accuracy of the Navier-Stokes program for this type of complex three dimensional flow. Initial predictions of the peak dynamic distortion patterns compare favorably with the test data and the computed dynamic distortion descriptors are qualitatively accurate at this time.