Boundary Layer Simulation using Wind Tunnel

Abstract

For understanding the effect of vertical strips (varying configuration viz. c/c spacing and height) placed on the upstream of the surface under taken for studies on the growth of boundary layer, the experiments were carried in the laboratory using Wind tunnel. The variables include vertical strips of heights 20 cm, 30 cm and 40 cm with fixed central spacing of 8 cm c/c. and then 30 cm strips at varying central spacing at 6.5 cm and 14 cm c/c. The wall clearance in each case was kept 2 cm from both sides. The growth of boundary layer was found to be significantly affected on strips configuration. The boundary layer thickness increases with increase in height of the vertical in the range of the experiment. Also, the boundary layer thickness has been found to decrease with increase in c/c spacing of the strips.
In the different section of wind tunnel reading of Boundary layer were taken with main stream velocity (U) which varies 10 to 12 m/s. With the concept of 99% (U) velocity profile is plotted at different location of working section length and the corresponding height is measured for the determination of Boundary layer.
The velocity of fluid increases from zero velocity on the stationary boundary to the free stream velocity of the fluid in the direction normal to the Boundary. This variation in velocity normally takes place in the vicinity of solid Boundary, and this narrow region is termed as Boundary layer. So our main aim is to enhance the Boundary layer thickness which is achieved by using many passive devices like spire, cube as roughness elements and vertical strips of different sizes.
My experiment is based on use of different size of vertical strips. Basically two things occur due to use of strips, one is it allows the formation of Vortex and consequent turbulence and second is it allows the air flow preferably on the upper part of the tunnel (main stream velocity).