Oil Film Interferometry Technique And The Application In Flow Control

In this paper, the relative researches of the boundary layer theory and fluid flow controltechnology have been studied. The backward facing step has been used to simulate the process offluid separation, and numerical simulation and experiments have been used to measure the skinfriction of the plate. According to the complexity flow over the backward facing step, some boundarylayer measurements with different techniques of flow control have been used, so that some reliablephenomenon can be investigated.First, the flow of different velocity has been simulated by numerical calculation, the resultsindicate that the stress coefficient becomes smaller when the distance between the plate’s front isfarther. Then, the shear stress is studied of a blunt body plate with roughness elements and has noroughness elements. The roughness element’s diameter is2.85mm, every10mm put a roughnesselement. In these experiments, two height of the roughness elements are chosen:1.0mm and1.5mm.The results show that the measurements of shear stress of oil film interference method are very closeto the results of CFD simulation. The study can also indicates that the results vary when there aresome roughness elements in the plate. The results show that the ability of the oil film interferometrymethod to measure the shear stress of airfoil and to provide foundations supporting its furtherdevelopment. Last, the Preston tube has been used to take measurements of the speed type ofupstream and downstream over the backward facing step, and then flow control measurements havebeen taken.