Flows in T-Junction Piping System (1st Report, Flow Characteristics and Vortex Street Formed by Branch Pipe Flow)

Abstract

Behavior of main and branch pipe flow in a T-junction piping system under the isothermal condition was examined experimentally using flow visualization techniques (the dye injection and smoke method). As a result, it was clarified that flows downstream of the T-junction are classified into three types : stratified flow, deflecting jet, and impinging jet. In the case of the deflecting jet, the flow issuing from the branch pipe into the main duct forms an arch vortex street. Next, the waveform of the axial velocity and its spectrum were measured by using hot wire, and the structure of the vortex was investigated. The frequency with which vortices are shed in an arch vortex street becomes higher with increasing Reynolds number under the condition of a constant velocity ratio and decreases with an increase in velocity ratio. Strouhal number is expressed by an approximate equation under the condition of Reynolds number Re=5000-50000, velocity ratio β=0.33-2.00 and diameter ratio α=2.04-5.20.