增压式脉冲水射流多脉冲特性试验研究

Experimental study on multi-pulse characteristics of pressurized pulsed water jet

射流尖端产生的水锤效应有助于硬岩的高效破碎.为进一步明确增压式脉冲水射流初始脉冲(射流尖端)特性,基于超高速成像系统,开展增压式脉冲水射流流场信息采集试验,并以晕轮为标记点,对射流多脉冲尖端的瞬时速度和穿透距离进行定量表征.结果表明:增压式脉冲水射流在单周期传播过程中孕育多重脉冲特征,多脉冲通过追逐-逼近及覆盖动态竞争成为初始脉冲,初始脉冲最大速度发生于第2脉冲之中.同时,多脉冲动态竞争导致射流存在“双峰”水锤优靶点,随着预定冲蚀靶距的增加,初始脉冲峰值速度发生位置由第1脉冲迁移至第2脉冲,这即意味着水锤优靶点由近喷嘴第1靶点迁移至远喷嘴第2靶点.研究结果为进一步利用增压式脉冲水射流初始脉冲提供依据和参考.

The water hammer effect generated by the jet tip contributes to the efficient crushing of hard rock.In order to further clarify the initial pulse(jet tip)characteristics of pressurized pulsed water jet,a high-speed imaging system was used to conduct information collection experiments on the flow field of pressurized pulsed water jet.The halo was used as a marker point to quantitatively characterize the instantaneous velocity and penetration distance of the multi pulse tip of the jet.The results show that the pressurized pulsed water jet nurtures multiple pulse characteristics during the single cycle propagation process,and the multiple pulses become the initial pulse through pursuit approximation and dynamic competition of coverage.The maximum velocity of the initial pulse occurs in the second pulse.At the same time,multi pulse dynamic competition leads to the existence of a“double peak”water hammer optimal target in the jet.As the predetermined erosion target distance increases,the position of the initial pulse peak velocity shifts from the first pulse to the second pulse,which means that the water hammer optimal target shifts from the first target near the nozzle to the second target far from the nozzle.The research results provide a basis and reference for further utilizing the initial pulse of pressurized pulsed water jet.