The Influence of Two-dimensional Stream Shear on Airfoil Maximum Lift

Download or read book The Influence of Two-dimensional Stream Shear on Airfoil Maximum Lift written by Robert J. Vidal and published by . This book was released on 1961 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effects of stre m v locity gradient on airfoil maximum lift are defined with experiment l da a ob ained in a simulated two-dimensional slipstream. The experime t l results show that w en po itioned near the slips ream plane of symmetry, the airfoil m ximum lift vari s markedly with location in the slipstream. In movi g he irfoil from abov to below the slipstream plane of symmetry through a total distance corresponding to the airfoil thickne s, force data and boundary-lay r observations show that boundary-layer separation is delayed to higher angle of a ck, a d the airfoil maximum lift is doubled. It is concluded that the destalling effect ob erved in t nonu ifor lipstream is o associated wit slipstream bou ry interferenc but stems from the influence of e large local slipstream shear on airfoil characteristics The effects of uniform no uniform shear on airfoil lift and pres ure dis ribution are discussed, within the framework of existing first-order, small-shear theory, to show that t ese effects of shear tend to promote stall. A Pohlhausen calculation of th laminary boundary layer in a stream with s ar is used to identify an to as ess the eff cts of stream shear on boundary-layer separation criteria.