Production of fine grain limestone by means of focusing and rounding water jets

为了明确水射流和聚焦磨粒射流破碎石灰石的适用性，进行了实验研究，为今后水射流磨的设计提供了基础数据。本文对水射流粉碎的可行性进行了实验研究，主要包括以下四个方面：1。通过冲击力测量估算水射流的入射速度，提出了一种评价水射流冲击岩石表面结构的实用方法，以阐明岩石的断裂机理。分析了圆柱形水射流垂直冲击平面靶板时产生的合力--冲击力，估算了圆柱形水射流的入射速度和表观密度.本文提出了一种适用于分析低速水射流垂直冲击岩石破碎和切割岩石时冲蚀过程的理论。考虑了非穿越和穿越两种情况.磨料水射流的破碎性能。细颗粒岩石被圆柱形水射流加速并撞击固体靶。分析了细颗粒岩石的破碎性能以及铝、低碳钢、硬质合金、氧化铝和锆等固体靶的冲蚀剖面.柯恩达喷嘴的内部流动及对粘性粉末分散的影响本文所研究的柯恩达喷嘴是一种类似于拉瓦尔喷嘴的射流泵。用单根倾斜热线风速仪测量了三维平均流场，并阐明了雷诺应力在粘性粉末分散中的重要作用远大于剪切应力。

In order to make clear the applicability of water jet and abrasive jet of focusing and/or rounding to the fragmentation of limestone, the experimental study has been performed and the fundamental data have been presented for the future design of water jet mill. The present experimental study on the possibility of water jet mill consists of four parts as follows :1. Estimation of incident velocity of water jets by means of impact force measurement.A practical method to evaluate the structure of water jets impinging onto the rock surface has been presented for the clarification of the fracture mechanism of rock. The impact force that is the resultant force imposed upon a plain-target by water jet impinging normally has been analyzed to estimate the incident velocity and the apparenet density of cylindrical water jets.2. Erosion characteristics of rock by water jet impingement.A theory is presented which is applicable to the analysis of erosion process in fragmentation and cutting of rock by a relatively low speed water jet impinging normally onto a rock surface. Both nontraversing and traversing cases are considered.3. Fragmentation performance of abrasive-water jet.Fine grain rocks have been accelerated by cylindrical water jet and impinged against a solid target. The fragmentation performance of fine grain rocks has been analyzed as well as the erosion profile of solid targets : aluminium, mild steel, hard metal, alumina and zirconium.4. Internal flow of coanda nozzle and effect on dispersion of cohesive powders.Coanda nozzle studied in this work is classified as a jet pump with a shape resembling the Laval nozzle. Three-dimensional mean flow has been measured by a single inclined hot-wire anemometer, and it has been clarified that Reynolds stress plays an important roll in dispersing cohesive powders is much greater than the shear stress.