曲がり円管内振動層流助走区間流れの可視化解析

抄録

Pictures have been presented for oscillatory laminar flow in the inlet region of circular curved pipes with long, straight tangents. Visualization of the flow was realized by the hydrogen bubble method and the time-dependent velocity profiles were grasped with reasonable accuracy. Their features substantiate the behavior of the developing oscillatory flow in dependence on the Womersley number α. Influences of the curvature radius ratio Rc and the Dean number D on the development are also investigated. From LDV measurements executed with reference to the visualization data, moreover, the inlet lengths of both the curved pipe and the upstream tangent are obtained in a wide range of the parameters and the formulas for them are presented as a function of D/α ²·Rc^1/2, which is effective when α>4. The inlet length of the upstream tangent is 1.5 times as long as one of the curved pipe.