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Contraction design for small low-speed wind tunnelsAn iterative design procedure was developed for 2- or 3-dimensional contractions installed on small, low speed wind tunnels. The procedure consists of first computing the potential flow field and hence the pressure distributions along the walls of a contraction of given size and shape using a 3-dimensional numerical panel method. The pressure or velocity distributions are then fed into 2-dimensional boundary layer codes to predict the behavior of the boundary layers along the walls. For small, low speed contractions, it is shown that the assumption of a laminar boundary layer originating from stagnation conditions at the contraction entry and remaining laminar throughout passage through the successful designs is justified. This hypothesis was confirmed by comparing the predicted boundary layer data at the contraction exit with measured data in existing wind tunnels. The measured boundary layer momentum thicknesses at the exit of four existing contractions, two of which were 3-D, were found to lie within 10 percent of the predicted values, with the predicted values generally lower. From the contraction wall shapes investigated, the one based on a 5th order polynomial was selected for newly designed mixing wind tunnel installation.
Document ID
19880012661
Document Type
Contractor Report (CR)
Authors
Bell, James H. (Stanford Univ. CA, United States)
Mehta, Rabindra D. (Stanford Univ. CA, United States)
Date Acquired
September 5, 2013
Publication Date
April 1, 1988
Subject Category
RESEARCH AND SUPPORT FACILITIES (AIR)
Report/Patent Number
JIAA-TR-84
NAS 1.26:182747
NASA-CR-182747
Funding Number(s)
CONTRACT_GRANT: NCC2-294
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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NameType 19880012661.pdf STI