Numerical investigation of flow resistance in cone-straight nozzle

Abstract

High-pressure water jet technology is applied to wellbore cleaning, descaling, auxiliary rock breaking, slit penetration, etc. In petroleum engineering. The cone-straight nozzle structure is widely used in the petroleum industry, and its internal flow resistance remains unclear, which plays an important role in nozzle geometry optimization and is the main research content in this paper. Large Eddy Simulations were used to simulate the near-wall flow field at a relatively low Reynolds number, the flow resistance is analyzed based on the numerical calculation data, and the following conclusions are drawn: The friction resistance is mainly distributed at the end of the converging section and the throat section, and there is a peak value, and the viscous force is mainly distributed in the converging section; the streamline structure can effectively reduce the skin friction resistance, and has little effect on the viscous force, which is more sensitive to the length of the nozzle; the streamline structure can change the trend of the total pressure in the nozzle, but has little effect on the kinetic energy conversion efficiency of the entire nozzle; increasing the fluid viscosity significantly increases the flow resistance in the nozzle. The purpose is to reveal the flow resistance inside the nozzle, investigate the factors affecting the flow resistance and provide theoretical support for the optimization of the nozzle structure.