Bleed has traditionally been used to improve the health of the boundary layer in supersonic aircraft engine inlets. However, the use of bleed adds mechanical complexity and increases the size of the inlet needed for a given engine mass flow requirement. Computational fluid dynamics (CFD) simulations in mixed compression inlets and small-scale shock-boundary layer interaction experimental and CFD results have shown that arrays of microdevices have the potential to reduce or eliminate the need for bleed. However, an inlet with microdevice arrays has not been tested in a wind tunnel. To provide baseline inlet data for a future inlet test with microdevices, researchers at the NASA Glenn Research Center tested a family of five external compression inlets in Glenn’s 1- by 1-Foot Supersonic Wind Tunnel. These inlets had neither bleed nor microdevices. The tests were performed under the Fundamental Aeronautics program and a partially reimbursable Space Act Agreement with Gulfstream Aerospace Corporation.
Inlet installed in Glenn’s 1- by 1-Foot Supersonic Wind Tunnel.
The inlets tested, which were based on a design developed by Gulfstream Aerospace Corporation, included a partially isentropic compression surface. The external compression surface was the same for all five inlets; they differed only in the subsonic diffuser length and in the centerbody diameter at the aerodynamic interface plane (AIP). Two subsonic diffuser lengths and three centerbody diameters were studied. The three inlets with the long subsonic diffuser were made with all three AIP centerbody diameters; the two inlets with the short subsonic diffuser were made with only the largest and smallest AIP centerbody diameters.
All inlet testing was done at a tunnel mach number of 1.97. The experimental test results were compared with CFD calculations done by Glenn and Gulfstream Aerospace Corporation. The Wind code was used for Glenn’s CFD calculations, and the Overflow code was used for Gulfstream’s calculations. NASA and Gulfstream CFD results compared well with each other and with the experimental results.
The CFD and experimental results from Glenn’s 1- by 1-Foot Supersonic Wind Tunnel will be used to determine which inlet design will be chosen for possible further study. In addition, a CFD study of this inlet may be done to determine the optimal location for an array of microramps. Then, a larger scale wind tunnel model may be tested in cooperation with Gulfstream Aerospace Corporation.
Find out more about the research of Glenn’s Inlet and Nozzle Branch: http://www.grc.nasa.gov/WWW/RTE/
Glenn contacts:
Dr. Kathleen M. Tacina, 216-433-6660, Kathleen.M.Tacina@nasa.gov
Stefanie M. Hirt, 216-433-6782, Stefanie.M.Hirt@nasa.gov
Bernhard H. Anderson, 216-433-5822, Bernhard.H.Anderson@nasa.gov
Authors:
Dr. Kathleen M. Tacina, Stefanie M. Hirt, Bernhard H. Anderson, Dr. Jason M. Merret, Timothy R. Conners, and Donald C. Howe
Headquarters program office:
Aeronautics Research Mission Directorate
Programs/projects:
Fundamental Aeronautics, Space Act Agreement with Gulfstream
Last updated: December 14, 2007
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