空化水射流破碎岩石的机理研究

Rock erosion mechanism of cavitating water jets

在不同泵压和淹没压力条件下,针对不同类型的空化喷嘴,对空化水射流的空泡云特性和破碎岩石机理进行了一系列实验研究,探讨了空化水射流的空泡云与冲蚀能力之间的相互关系。优化空化喷嘴结构和工作条件以减小泵压,从而降低输入能量。空泡云的可视化研究显示缩放形喷嘴产生的空化云的长度和宽度比收敛形喷嘴的大。研究表明,空化水射流切割破碎岩石主要是由空泡的溃灭引起的,空泡云的长度等于靶距与切割深度之和;在切割破碎岩石时冲蚀效果只在开始几秒内发生,冲蚀深度并不随时间而增大。

A series of experiments relating to bubble cloud and erosion mechanism of cavitating water jets were carried out for different nozzles with different pump pressures and ambient pressures. The objective of this work is to find the relation between the erosion and the bubble cloud, determine drilling parameters such as the feed speed or rotating speed for a water jet drilling system, and explore nozzle operating conditions and nozzle designs to reduce the input energy by reducing the pump pressure. Visualization studies of the bubble cloud show that the length and width of the bubble cloud of the convergent-divergent nozzle are larger than those of the convergent-straight nozzle. The erosion tests confirm that it is the bubble collapse that causes the erosion, and the standoff distance plus the drilling depth equals to the bubble cloud length. In drilling brittle hard rock, erosion happens in the first few seconds, and after that, erosion does not increase with time.