Experimental investigation of shock manipulation by the use of trailing edge brushes on a supercritical airfoil at transonic speeds

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Throughout the project the degradation of upstream moving pressure waves by the use of trailing edge brushes and their effect on the transonic flow around the supercritical BAC 3-11 airfoil is investigated. The influence of the waves on the formation of the shock is of special interest. Previous schlieren pictures indicate that the bunching of pressure waves is involved in the formation of the shock. The results of preliminary experiments support the theory that the trailing edge brushes can delay the shock formation to higher Mach numbers.Within the single working packages the wave behavior itself will be analyzed, the most effective brush parameters will be defined as well as the overall influence of the waves and the brushes on the airfoil aerodynamics will be deduced. Therefore the diameter and length of the brush, the Mach number and the angle of attack will be systematically varied. Hence empirical design specifications for the brush will be established.Additional experiments will be done in the trisonic wind tunnel at the Institute of Aerodynamics at RTWH Aachen University to validate the results and to make sure there were no influences of wind tunnel interference in the Transonic Shock Tube (STK).The results will be implemented in a physical model of the wave movement based on equations for pressure waves over an oscillating airfoil. Finally there will be the possibility to transfer the design standards of the trailing edge brush and the physical model of the wave movement via similarity rules to real flight conditions.