Kinematic characteristics of two-phase flows in waterjet cutting

Introduction. In waterjet cutting, a two-phase flow consisting of water and abrasive solid particles moves at a high average speed. Destruction of hard materials and alloys requires a large force and, therefore, a high flow rate. Such flows differ utterly from natural and well-studied flows in hydraulic transport and hydroprocessing. Determination of kinematic characteristics in the waterjet cutting is an independent task. Materials and methods. The results of field studies to determine the essential kinematic characteristics of the two-phase flow are presented. The conditions of transporting the solid particles, the efficiency of their application in cutting as well as the assessment of energy losses. The revelation of features of the two-phase flows and differences from water flows is a part of engineering calculations aimed at the effectiveness of their use in various fields of activity, including firefighting. Results. The calculations of the two-phase flow heterogranularity, the weighted average density of the particles constituting the solid phase, the flow volume density, and actual flow density were carried out. Calculations of the two-phase flow density were performed by а volume-weight method and by integrating the solid particle density distribution in depth. Conclusions. The paper showed that in waterjet cutting the actual density exceeds the flow volume density by 8.5 % what is lower than the values recommended for hydraulic transport. All the engineering calculations must be conducted using the values of the actual flow density. The kinematic characteristics obtained in this work are the basis for the calculation of additional head losses per 1 meter of a firefighting unit hose during transportation.