Effects Of Boundary Layer Type Humidity And Porosity Distribution On Transonic Drag Reduction By Passive Shock Wave Boundary Layer Control For A 14 Supercritical Airfoil

Masters Theses in the Pure and Applied Sciences was first conceived, published, SIld disseminated by the Center for Information and Numerical Data Analysis and Synthesis (CINDAS) * at Purdue University in 1957, starting its coverage of theses with the academic year 1955. Beginning with Volume 13, the printing and dissemination phases of the activity were transferred to University Microfilms/Xerox of Ann Arbor, Michigan, with the thought that such an arrangement would be more beneficial to the academic and general scientific and technical community. After five years of this joint undertaking we had concluded that it was in the interest of all con cerned if the printing and distribution of the volumes were handled by an interna and broader dissemination. tional publishing house to assure improved service Hence, starting with Volume 18, Masters Theses in the Pure and Applied Sciences has been disseminated on a worldwide basis by Plenum Publishing Cor poration of New York, and in the same year the coverage was broadened to include Canadian universities. All back issues can also be ordered from Plenum. We have reported in Volume 30 (thesis year 1985) a total of 12,400 theses titles from 26 Canadian and 186 United States universities. We are sure that this broader base for these titles reported will greatly enhance the value of this important annual reference work.

A growing research effort is being mounted in a number of countries into investigations of ideas for drag reduction, some novel and some that were looked at in the past but were not then pursued to the point of application because the economic facts of life were different from and less pressing than they are now. These ideas include means for reducing skin friction drag (e.g. compliant walls, boundary layer control, etc.), induced drag (e.g. winglets), interference drag, transonic shock wave drag (supercritical wings) and supersonic wave drag. In addition the internal aerodynamics of ducting, especially diffusers is receiving attention to improve the performance of engines.

With an approach of the velocity of flight of a ship to the velocity of sound, there occurs a considerable increase of the drag. The reason for this must be found in the boundary layer separation caused by formation of shock waves. It will be endeavored to reduce the drag increase by suction of the boundary layer. Experimental results showed that drag increase may be considerably reduced by this method. It was, also, observed that, by suction, the position of shock waves can be altered to a considerable extent.

At subsonic speeds, full length laminar flow and low drags were obtained up to high length Reynolds numbers on a thin straight, on a swept laminar suction wing and on a suction body of revolution. Moderately increased suction rates in the most critical region of a straight and a swept laminar suction wing enabled full chord laminar flow in the presence of external sound. Theoretical investigatiions are concerned with nonlinear boundary layer oscillations and stability investigations (assuming small disturbances) of a supersonic laminar boundary layer on a flat plate up to high supersonic speeds as well as on a highly swept supersonic low drag suction wing of low wave drag. On a supersonic flat laminar suction plate with and without weak incident shock waves, extensive laminar flow and low equivalent drags were obtained at M = 3 up to length Reynolds numbers of 26 x 1000000. Further supersonic low drag suction experiments on a suction body of revolution, on a 36 degree supersonic yawing wing, as well as on a 72 degree supersonic yawing wing (swept behind the Mach cone) of low wave drag, are described. The latter wing showed full chord laminar flow with a subsonic type pressure distribution at M = 2 and R sub C approximately equal to 1000000. (Author).