Abstract: The jets of star-shaped and round nozzles are different.The attenuation characteristics of the two jets were investigated experimentally.The dynamic attenuation mechanism of the jets was discussed.It is found that the star-shaped nozzle jet has a shorter initial section and slower velocity attenuation along the jet centerline in the main region than the round nozzle jet.Within a standoff distance equal to about seven times of equivalent nozzle diameters, the jet centerline velocity of the star-shaped nozzle is lower than that of the round nozzle.When the jet distance is beyond the scope of this critical standoff distance,the jet velocity of the star-shaped nozzle is greater than that of the round jet.The biggest velocity and the dynamic pressure of the star-shaped nozzle jet are in a 20 percent and a 44 percent increase respectively than those of the roand jet.

Key words: star-shaped nozzle, jet, jet distance, velocity field, attenuation, mechanism, experimental study

摘要： 对近期清洗行业出现的星形喷嘴射流进行了淹没条件下的实验研究。利用粒子成像速度场仪对星形喷嘴射流的速度场进行了测量,分析了星形喷嘴的射流衰减机理。实验发现,星形喷嘴射流与普通圆射流相比,其射流初始段较短,但基本段内速度随喷距衰减的速率较低。在7倍于喷嘴直径的喷距以内,星形喷嘴射流的速度低于圆射流速度。随着喷距的进一步增加,星形喷嘴射流的速度高于圆射流速度。在10～12倍于喷嘴直径的喷距范围内,星形喷嘴射流的最大速度和最大动压力分别提高了约20%和44%。该项研究为星形喷嘴射流在石油钻井工程中的应用提供了依据。

关键词: 星形喷嘴, 射流, 喷距, 速度场, 衰减, 机理, 实验研究