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The Second Order Terms in Two-Dimensional Tunnel Blockage

Published online by Cambridge University Press:  07 June 2016

L. C. Woods
L. C. Woods*
Affiliation:
formerly New Zealand Scientific Defence Corps, seconded to the Aerodynamics Division of the National Physical Laboratory; now Lecturer, University of Sydney
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Summary

This paper gives a new calculation of the solid and wake blockage for compressible subsonic flow about a symmetrical two-dimensional aerofoil, midway between symmetrically disposed tunnel walls, which need not be straight. Previous calculations have been based on the theory of sources, and the results obtained have usually involved only first order terms. At high subsonic Mach numbers the second order terms become important; they are given in this paper. The theory is based on an integral equation, which is exact for incompressible flow, and which is more accurate than linear pertubation theory in compressible flow. The effect on blockage of a possible increase in the boundary layer displacement thickness on the tunnel wall, due to the presence of the aerofoil, is investigated, and finally a method of calculating the total blockage from wall pressure measurements is given.

Type
Research Article
Information
Aeronautical Quarterly , Volume 4 , Issue 4 , February 1954 , pp. 361 - 372
Copyright
Copyright © Royal Aeronautical Society. 1954

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References

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