Experimental Investigation On Moving Surface Boundary Layer Control

Moving Surface Boundary-Layer Control (MSBC) have been widely used in moving belt of wind tunnel for investigation on ground effect. It prevents the initial growth of boundary layer by minimizing relative motion between the surface and free stream, and it injects momentum into the existing boundary layer. It has attractive features. With low power consumption, it can significantly increase lift and delay stall of airfoils, reduce drag of bluff bodies, and it can even suppress the wind induced vibration. Foreign investigators have been trying to applied it to the development of airplanes and vehicles, and suggesting possible application in the next generation of civil engineering structures. They have carried out many programs and been making progress for about two decades. In recent years, domestic researchers have also showed deep concern for MSBC because of the development of aviation and land traffic. The investigation should start with experiment for its importance.The moving surface was provided by rotating cylinders in this paper. Three testing apparatus have been developed for this program. The effects of MSBC on plate and NACA0015 airfoil have been assessed, and the mechanism has been investigated by flow visualization. For the first time, MSBC was applied to locomotive wind tunnel test.The results show that MSBC can obviously enhance lift and reduce drag and delay stall by suppressing or delaying separation of the boundary layer. The performance can be improved further by judicious selection of the rotating cylinder surface condition and the ratio of cylinder surface speed to the freestream velocity. The newly developed apparatus have been proved successful in initiatory stage. It provides important experimental fundament for next program. The adverse flow from lower surface to upper surface at leading edge has been described in this paper for the first time.