Turbulent Contamination of Laminar Flow due to Free Stream Particles

摘要: Laminar Flow technology is known to be detrimentally affected when encountering ice crystals as occurring in cirrus cloud. However, the principle mechanisms leading transition of a laminar boundary layer due small particle travelling through it are not well understood. Moreover, previously-proposed critical parameter had been experimentally verified. Difficulties encountered during efforts re-create naturally laboratory led development an alternative approach. This based on surface moving within fluid that otherwise at rest, thus reversing conventional approach wind tunnel. Proceeding such alleviates investigations particles equilibrium free stream before entering layer, since allows for positioning fixed location while involved processes slowed down. Preliminary computational analysis resulted encouraging data with regard feasibility proposed method. Although, first practical involving newly-developed test facility showed some differences numerical prediction, flow field was obtained, representing workable environment this purpose. Subsequent more detailed measurements surprisingly close match obtained velocity profile compared Blasius solution. Both single hot wires and smoke visualisation were proven unsuitable conducting desired investigations. Subject upgrade employed measurement techniques (e.g. crossed or PIV) fabricated likely produce missing answers wake wall-bounded non-uniform flow.