Skin-Friction Measurements in An Incompressible Pressure-Gradient Turbulent Boundary Layer. Review of Techniques and Results

摘要

Experimental definition of the local and integral values of friction drag of an aircraft or its elements is one of the basic problems of applied aerodynamics. We also should note the undoubted significance of this value for the development of modern lifting profiles and other aircraft elements, the description of near-wall flows in a form of similarity laws and testing of the numerical techniques of computation of flow around such aircrafts. However, to define this value accurately, one should have a clear conception of the possibilities and efficiency of application of one or another technique for a special case of body flow around. Though any experimental work assumes application of a certain concrete technique, including one for skin friction finding, the available literature information is as a rule uncoordinated, i.e., this information reflects only the level of availability of the technique applied. For this reason the researches like devoted to the development of new techniques and investigation of the efficiency of the known ones under various experimental conditions, become very important. The simplified layout gives a pictorial view of the main techniques of skin friction measurement, existing at the present time. The detailed consideration of these techniques is given in The present paper presents a comparative analysis of a number of direct and indirect measuring techniques wen they are applied in a incompressible turbulent boundary layer of a flat plate under the conditions of formation of a unfavorable (positive) and favorable (negative) streamwise pressure gradients on the plate surface, and also in plate gradient-free flow around.