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STOVL Jet Recirculation

Michael Malone at Northrop-Grumman's B-2 Division used Gridgen to generate grids for a CFD simulation that accompanied an experimental study of hot gas ingestion for Short Take-Off Vertical Landing (STOVL) vehicles. The test configuration (shown below) consists of two vertical nacelles, shown in grey. The vertical pipes (red) supply the hot nozzle flow which is ejected downward from the nacelles into the ground plane (green). The horizontal pipes (blue) provide suction to simulate an operating jet engine drawing air in through the 180 degree inlets at the top of each nacelle (the interior of the inlets are yellow). Instrumentation, including pitot probes and thermocouples, was installed on the thin plate (orange) mounted between the two nozzle supply pipes.

Downward Facing Nacelles

A closeup of one nacelle is shown below.

Nacelle Close-Up

The multi-block structured grid consisted of a combination of abutting and overlapping blocks. The intricate detail of a few of the symmetry plane meshes is shown below. A quarter-symmetry model was used in the actual CFD analysis and included a total of 8 blocks and approximately 1.8 million grid points.

Overlapping Symmetry Plane Grids

The experimental results are documented in NASA CR-1307 (Sept. 1968) "Recirculation Effects Produced by a Pair of Heated Jets Impinging on a Ground Plane" by Gordon R. Hall and Kenneth H. Rogers. The CFD results are documented in "Airframe/Engine Compatibility Analysis on Advanced Parallel Computing Systems" (NASA contract NAS2-14093), August 1995.