A study on separation control mechanisms of tandemly arranged wing with linear leading edge and leading edge protuberance

Abstract

A study on separation control mechanisms of tandemly arranged wing with linear leading edge (LLE) and leading edge protuberance (LEP) in low Reynolds number was conducted. In this study, to investigate the separation control mechanism, we carried out the visualization experiment using smoke-wire method, the streamwise and spanwise velocity measurements above the upper surface of the backward wing by using hotwire anemometer, and the numerical simulation. From the results of flow visualization experiment, it was found that the high lift coefficient obtained by tandemly arranged wing with LLE and singly and tandemly arranged wing with LEP were caused by reducing the flow separation region. From the results of velocity measurements and numerical simulation, it was found that in the case of wing with LLE, the turbulence generated by forward wing, which had mainly streamwise component with peak frequency of 230Hz and broadband frequency over than 30Hz, controled the flow separation. Whereas in the case of wing with LEP, regardless of the wing arrangement, separation control was brought by the separation bubble that caused by the longitudinal vortices generated by the LEP. It was also found that the turbulence from forward wing affected the position of the valley part where the separation bubble and the strong negative pressure were formed.