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The theoretical and experimental work carried out under the NASA /MOD joint aeronautical program has shown that computational uid dynamics (CFD) vortex-generator installation designs successfully managed inlet-duct ow distortion and that signi cant bene ts in ow unsteadiness at the engine face were also present. The main conclusions to date from the collaborative effort between the NASA Lewis Research Center and the Defence Research Agency in Bedford are as follows: 1) Vortex-generator installations can be designed to be effective over a wide range of inlet operating conditions using CFD and formal optimization procedures, 2) reductions in steady-state engine face distortion of up to 80% have been measured in the M2129 inlet S-duct using CFD-designed vortex-generator installations, 3) reductions in ow unsteadiness of up to 80% have been measured in the M2129 inlet S-duct using CFD-designed vortex-generator installations, and 4) the reduced Navier-Stokes code RNS3D is a useful tool to design vortex-generator installations to manage engine-face distortions over a wide range of inlet operating conditions. NomenclatureA = ow area c = vortex-generator chord length D = diameter DC60 = circumferential total-pressure distortion descriptor d = vortex-generator lateral spacing h = vortex-generator blade height M = Mach number Pt = total pressure Pt av = average total pressure Pt max = maximum ring total pressure Pt min = 60 deg-sector minimum ring total pressure Pt 0 = freestream or reference total pressure Q = face-average dynamic pressure R = radial distance X = axial distance from inlet throat vg = vortex-generator spacing angle vg = vortex-generator incidence angle ef = dimensionless engine-face radial distance * = displacement thickness s = installation sector angle Subscripts ef = engine face i = inlet-throat station ring = ring rms = total pressure RMS value sep = separation Received April 3, 1996; presented as Paper 96-3279 at the AIAA / ASME /SAE/

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