BOUNDARY LAYER ON FLAT PLATE WITH LEADING EDGE PATTERNS

Abstract

THE DEVELOPMENT OF STREAMWISE COUNTER-ROTATING VORTICES IN THE BOUNDARY LAYER OF A FLAT PLATE HAS BEEN EXPERIMENTALLY INVESTIGATED BY MEANS OF SMOKE-WIRE FLOW VISUALIZATION AS WELL AS THE HOT-WIRE ANEMOMETRY. DIFFERENT LEADING EDGE PATTERNS SUCH AS TRIANGULAR, SINUSOIDAL AND NOTCHED PATTERNS WITH IDENTICAL WAVELENGTH AND AMPLITUDE WERE USED TO PRODUCE UNIFORM SIZE VORTICES. IN ADDITION, THE EFFECT OF THE AMPLITUDE AND WAVELENGTH ON THE VORTEX STRUCTURE WAS STUDIED FOR THE TRIANGULAR LEADING EDGE. IT WAS FOUND THAT STREAMWISE COUNTER-ROTATING VORTICES IN THE FORM OF MUSHROOM-LIKE STRUCTURES INITIATED FROM THE TROUGH OF THE PATTERNS. THE NUMBER OF THE PRESET VORTICES WAS EQUAL TO THE NUMBER OF TROUGHS OF EACH PATTERN, EXCEPT FOR THE NOTCHED PLATE. AN ADDITIONAL VORTEX STRUCTURE APPEARED BETWEEN THE MAIN COUNTER-ROTATING VORTICES ON THE NOTCHED PLATE. AN INFLECTION POINT WAS DETECTED ON THE VELOCITY PROFILE AT UPWASH REGION AT THE BEGINNING OF THE VORTEX FORMATION DUE TO THE NON-LINEAR GR