Abstract:

ESDU 05022 gives an introduction to the principles of dynamic similarity and its application to wind-tunnel testing, with particular reference to the testing of transport configurations in the transonic speed range. Inherent limitations that prevent the complete achievement of dynamic similarity in a wind-tunnel test are described. Scale effects arising from the influence of Reynolds number on the boundary layer are discussed and particular reference is made to transition, separation and shock wave-boundary layer interaction. Phenomena associated with wind-tunnel testing but which may be interpreted, erroneously, as a genuine Reynolds number dependency in the flow under examination (pseudo Reynolds-number effects) are also discussed.