Experimental Study on Friction Pressure Drop Characteristics of Simple Harmonic Pulse Flow Pole Point

Friction pressure drop characteristics of the pole points of simple harmonic pulse flow were studied experimentally and theoretically.The comparison between the calculated results through the steady flow friction pressure drop empirical equation showed that the experimental friction pressure drops of crest point are lower than the calculated result,and the cases in trough point are opposite.The difference between the calculated and experimental data increased with the increase of pulse intensity（mean flow rate and pulse amplitude increasing,pulse period decreasing）.The velocity distribution of flow cross section of steady flow,crest and trough points were calculated,and the results showed that the increase of velocity grad along the diameter direction at trough point caused the increase of friction pressure drop.