抄録
The interfacial shear stress was evaluated experimentally for a wavy, horizontally-stratified air/water two-phase flow. The experiments were conducted using a 0.7-m high, 12-m long rectangular duct for four different air superficial velocities (jg=4.2 to 6.8m/s) with water superficial velocity fixed at jl=0.3m/s.
The wall shear stress distribution was measured using a Preston tube at five locations along the test section. The wall friction coefficient, derived from the shear stress, deviated from the Blasius smooth-surface correlation with an increase in the wave amplitude, but stayed within ±30% of the correlation. Based on the measured wall shear stress, together with the measured static pressure drop and water level, the interfacial shear stress was evaluated from the one-dimensional steady-state momentum balance for the air flow. The derived interfacial shear stress τi increased with an increase in the wave amplitude which increase with both jg and the distance from the duct inlet L. The interfacial friction coefficient evaluated from τi was 4 to 10 times larger than the smooth-surface value, predicted by the Blasius correlation.
