A Review of Scale Effects on Surfaces in Unsteady Motion,
ROYAL AEROSPACE ESTABLISHMENT BEDFORD (UNITED KINGDOM)
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The importance of scale effects is recognised generally in steady aerodynamics but is often ignored in unsteady aerodynamics. An attempt is made to remedy this situation by the compilation of a review of information on the influence of Reynolds number from a wide range of unsteady aerodynamic tests, with particular reference to wing flows. The unsteady tests considered here relate to surfaces in unsteady motion and include dynamic tests of aerofoils and wings, pressure measurements, oscillatory control surface derivatives, and stability derivatives. The review suggests that for the recommended model conditions with fixed transition, scale effects are small for fully-attached or well-separated flows, but may be large close to incipient separation. With fixed transition extrapolation from model to full-scale Reynolds numbers is usually possible. In contrast, with free transition, scale effects can be large for both attached and separated flows, and extrapolation from model to full-scale Reynolds numbers is usually extremely difficult.
- Fluid Mechanics