THE paper reviews the problem of the influence of the walls of a closed tunnel in increasing the velocity in the neighbourhood of a model under test. It is shown that, for a perfect fluid, considerations of continuity suffice to establish an exact value of the mean interference velocity for any cross‐section of the tunnel. This mean interference velocity is expressed in terms of the perturbation velocity which would be caused by the same model in the absence of the walls. The linearized theory of subsonic compressible flow is applied and it is shown that the interference velocity for a small two or three dimensional model is increased in proportion to l/β3, where β=√(l—M2) and M is the Mach number. Interference caused by a body with a long parallel middle body, the influence of the wake from a model and of the boundary layer on the tunnel walls are briefly considered.
Duncan, W.J. (1949), "A Simple Approach to Wind Tunnel Constriction Effect: The Problem of the Influence of the Walls in Increasing the Velocity in the Neighbourhood of a Model under Test", Aircraft Engineering and Aerospace Technology, Vol. 21 No. 6, pp. 180-183. https://doi.org/10.1108/eb031771
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