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Numerical Simulations of an Unsteady Rocket Launch from the AH-64D Apache Longbow HelicopterRocket and missile firings from attack helicopters can cause main engine compressor stall. Studies of this phenomenon suggest that the main engine ingests either the plume from the rockets or the rocket blast waves. This creates surges at the inlet face, causing a loss of power in the main engine. The objective of this project is to set-up a computational fluid dynamics (CFD) simulation of the AH-64D Apache Longbow helicopter during a rocket launch, in order to qualitatively study the fluid dynamics of the problem. This project presents a progression of three unsteady Navier-Stokes solutions. The first unsteady solution involves only a rocket launch from its launch canister. The second solution is a launch from a canister mounted on the Apache's wing-pylon assembly. The last solution includes the Apache main engine and fuselage. The computations use a series of structured, overset grid systems, which allow for a rocket moving in a prescribed path. The method implements a Roe upwind scheme with LU-SGS (lower-upper factored symmetric Gauss-Seidel). A rotor pressure disk model approximates the helicopter rotor, while the rocket engine exit properties are applied as a prescribed boundary condition. Although the project is only at the half-way point, the first and second CFD simulations suggest the possibility of pressure wave interference. Sudden surges in pressure occur from two sources: at rocket start-up, and as the rocket leaves the canister. Wave patterns set-up by these sources appear to propagate to the location of the engine inlet. However the simplified geometry simulation with the main engine needs to be performed before coming to a conclusion.
Document ID
20020066703
Acquisition Source
Ames Research Center
Document Type
Conference Paper
Authors
Okamoto, Kevin
(MCAT Inst. United States)
Dugue, Earl P. N.
(MCAT Inst. United States)
Ahmad, Jasim
(MCAT Inst. United States)
Rutkowski, Michael
Date Acquired
August 20, 2013
Publication Date
January 1, 1998
Subject Category
Numerical Analysis
Meeting Information
Meeting: 4th Symposium on Overset Composite Grid and Solution Technology
Location: Aberdeen Proving Ground, MD
Country: United States
Start Date: September 23, 1998
End Date: September 25, 1998
Funding Number(s)
CONTRACT_GRANT: NAS2-14109
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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