Aerodynamic Characteristics of Moving Trailing-Edge Controls at Subsonic and Transonic Speeds

摘要

This paper compares oscillatory pressures calculated and measured at high subsonic speeds for a swept back wing of aspect ratio 6 with a part-scan trailing-edge flap. The flap was driven at frequencies of 1 Hz (quasi-steady) and 90 Hz at Mach numbers from 0.40 to 0.95 with both fixed and free transition over a range of Reynolds numbers from 1 million to 4 million. The measured oscillatory pressures depend strongly on the boundary-layer displacement thickness at the hinge line. Hence extrapolation from model to full scale requires great care. In subsonic flow, tests with free transition give the thinnest turbulent boundary layer at the hinge line and come nearest to full scale. However, at transonic speeds transition should be fixed at a safe distance up-stream of the most forward excursion of the shock wave to obtain results appropriate to higher Reynolds number. Tests with flap driven simultaneously at two frequencies (90 Hz and 131 Hz) at subsonic and transonic speeds produce the same oscillatory pressures at 131 Hz as when driven independently. Hence the principle of superposition applies, at least for small amplitude motions with attached flows. (Author)