Title: COMBINED EFFECT OF SUCTION AND PRESSURE GRADIENT ON SEPARATION OF SUPERSONIC BOUNDARY LAYER
Abstract: The effect of pressure gradient on separation of supersonic compressible boundary layer is studied at two different Mach numbers of 5.0 and 6.0.Moreover, the study of constant suction effect at different locations is performed for flow at Mach number 5.0.The non-similar boundary layer equations for steady compressible flow have been solved with a potential flow velocity distribution corresponding to power law edge Mach number variation.In this study, the changes in Prandtl number and the specific heat with temperature are considered.The resulting conclusion show that the higher adverse pressure gradient is less affected by a constant suction than the lower one. 1-IntroductionThe factors that influence the transition of incompressible and compressible boundary layer flows include pressure gradients, wall roughness, heating or cooling, free steam turbulence, suction or blowing, streamwise curvature, and radiated acoustic noise.The effect of pressure gradients (wall shaping) on laminar flow is of particular interest because it is a passive device for controlling the boundary layers.Previous investigation, have shown that a favorable pressure gradients accelerate the velocity while adverse pressure gradients produce an opposite effectl.The studies in compressible boundary layers are more complicated than in incompressible, the former case is rare, and the most investigations take some restrictions conditions on prandtl number2 , or the relation between the tempreaturel.Self-Similar .solutions for non-zero pressure gradients ,are comprepsible boundary,layers8, Malik3 used a self-similar solution do not exist for the investigated conditions, Recently the nonsimilar solutions were studied2 consideti ng the prandtl number and the specific heat as constants.Flow with suction through a porous wall and cooling are of practical interest.Suction delays both transition to turbulence and boundary layer separation in an adverse pressure gradient.The application of suction at a surface decreases the boundary layer thickness and causes the velocity profile to become more full, that is, the greater the suction, the more deviation of velocity profile from one with inflection point4.