Unsteady Pressure and Boundary Layers on an 0012 Airfoil Caused by Aerodynamic Interference
Annual rept. 1 Sep 1981-31 Aug 1982
MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF AERONAUTICS AND ASTRONAUTICS
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Aerodynamic characteristics have been measured for a NACA 0012 airfoil in a non-uniform unsteady flow field. Test parameters studied included reduced frequencies based on semichord of 0 to 6.4 Reynolds number of 700,000 to 1,450,000, and airfoil angles of attack of 0 to 15deg. Quantities measured were upwash velocity fields, turbulent boundary layer velocities and Reynolds stresses, and attached and separated flow pressure distributions. The influence of frequency, pressure gradient, unsteady amplitude and measurement location are discussed. Results are compared with previous results and physical models for steady and unsteady flows. Superposition of unsteady and mean quantities appears to be valid for low pressure gradient attached flow, but becomes increasingly inadequate as separation is approached. Propagation of unsteady pressures in separated flow resembles a superposition of a disturbance convected downstream from the leading edge onto the standing wave patter found in attached flow, but includes numerous additional complexes.
- Fluid Mechanics