Effects of inclination on radial distribution of interfacial parameters were investigated for air-water bubbly flow in a pipe with the diameter of 50 mm.The double optical fiber probe method was used for measuring the local parameters of void fraction

interfacial area concentration and bubble passing frequency.Air and water were used as working fluids

with the superficial velocities of 0.002—0.037 m·s-1 and 0.072—0.569 m·s-1

respectively.Three inclination angles of 5°

15° and 30° were selected for the experiments.Four classical distribution types of the core peak

wall peak

intermediate peak and transition appeared under vertical flow condition.While for the inclined condition

bubbles congregate toward the upper wall of the pipe

resulting in the asymmetrical distribution of these parameters.The central broad peak leaned to the upper part of the tube

with its peak value increasing as the inclination angle increased.In the meantime

the peak near the lower wall lowered gradually

even disappeared

while the other one near the upper wall escalated accordingly.The interfacial parameters increased diametrically from ri/R=-0.84 to the peak location around the upper wall

with its variation rate increasing as the inclination angle increased.The Sauter mean diameter under inclined condition were larger than that of vertical flow.