Aerodynamic analysis of a distortion screen with a three-dimensional viscous fluid dynamics code

A time-dependent flow solver for the Euler equations and thin-layer Navier-Stokes equations has been adapted for the study of duct flow through wire-mesh screens. A computer program has been developed to analyze the flow properties produced by a pressure-distortion screen typically used in turbine engine testing.

The two-dimensional and three-dimensional finite-difference codes, developed by Pulliam and Steger, have been modified to include source terms in the governing equations to model a distortion screen with a given porosity distribution. The source terms are derived from empirical data to simulate the effects of drag forces produced by the distortion screen on the fluid flow. These codes are based on the implicit approximate factorization algorithm of Beam and Warming.

A three-dimensional grid is generated to define the computational mesh for the flow region of a cylindrical duct containing a distortion screen. The grid extends for a limited distance upstream from the screen to the entrance of a compressor inlet face containing an engine bulletnose.

Sample cases have been examined to allow quantitative verification of the solution technique by comparison with measured screen calibra tion data. A comparison has also been made to an inviscid analytical solution of parallel flow through and around a flat screen placed normal to the flow. The results have proven to be consistent with the measured data within an acceptable degree of error.