Experimental Study of Friction Characteristic in Circular Pipe subject to Low Frequency Pulsating Turbulent Flow

摘要

Friction characteristics subject to low frequency pulsating flow in a circular pipe are studied experimentally. The experiments are carried out for different pulsation frequencies, amplitudes and cycle-average Reynolds numbers. The results shows that when the flow rate fluctuates in sine law with time, the pressure drop fluctuates with the same frequency, however, there is a phase difference between the two, and it changes with the cycle-average Reynolds number but have no variation with amplitude and period. During the acceleration phase of the half cycle a laminar-like flow appears that the friction factor changes linear with the Reynolds number. In addition, an empirical equation for the cycle-average friction factor incorporating the effect of pulsation frequency, amplitude and cycle-average Reynolds number is obtained.