Vortex Flow Developed in the Vicinity of a Wall of an Elastic Heaving Airfoils and its Dynamic Behavior

Abstract

A number of studies on wake structures and the characteristics of dynamic thrusts of an unsteady airfoil have been reported. However, behaviors of vortices that from wake structures and processes from generation to development have not been clarified. The authors measured a flow field in the vicinity of a wall including boundary layer of heaving rigid airfoild and elastic airfoil by PIV measurements and clarified the growth process of votices generated in the vicinity of the wall quntitatively. In addition, we measured the acceleration of trailing edge and clarified changes of growth process of vortices generated in the vicinity of the wall by changing of acceleration of trailing edge of heaving aorfoil. The vortices generated in the vicinity of the wall grow up rapidly when acceleration of heaving motion becomes the maximum. Furthermore, the vortices generated in the vicinity of the wall keep growing up until the acceleration of the trailing edge of heaving airfoil becomes the maximum. Therefore, the growth and development of the vortices generated in the vicinity of the wall of heaving airfoil's trailing edge strongly depend on the acceleration variations of the trailing edge.