S0510206 二次元オフセット噴流の流動特性([S051-02]噴流,後流およびはく離流れ現象の探求と先端的応用(2),流体工学部門)

抄録

Fluid flow characteristics of two-dimensional offset jet are investigated experimentally. The offset jet is produced by the flow of air which issue from the end of a long parallel channel. The exit Reynolds number Re is changed in 1.5×10^3 to 7.0×10^3, and the offset ratio H/h (H:step height, h:channel height) is changed in 0.5, 1.0 and 1.5. The wall shear stress is measured using a micro flow sensor. Flow visualization is carried out using a CCD camera and laser light. In the laminar flow region downstream of the reattachment point, fluid in the outer region has a counter-clockwise vorticity and fluid in the inner region has a clockwise vorticity, and a lifting-off of the wall jet flow into the ambient fluid is occurred. In the turbulent flow region, the formation of those vortices is not seen. Two peaks exist in the local skin friction coefficient distribution of the laminar flow with H/h=0.5 and 1.0. The 1st peak appears just downstream of the reattachment point, and the 2nd peak appears in the neighborhood of the lifting-off of the wall jet flow. The Strouhal number is almost constant regardless of an offset ratio.