Numerical investigating flow characteristic of swirling turbulent round jet

Abstract

Swirling waterjet, using swirling and cutting capacity of high velocity waterjet beam, is a kind of technology widely applied in foundation processing, tunnelling, coalbed methane mining, and etc. It is extremely complicated because the existence of high velocity gradient and swirling, nevertheless, knowing unsteady interior flow characteristic and flow pattern which tremendously affects cutting capacity of waterjet is what we concern about. In this article, computational fluid dynamics is utilized to study flow characteristics of swirling turbulent waterjet, convergent nozzle structure with swirling is chosen as prototype and investigational region is selected as waterjet flow could be fully developed, structured mesh and grid number independent is obtained, Reynolds stress turbulence model is employed and standard wall functions is chosen as the near-wall treatment, pressure boundary conditions are applied on inlet and outlet boundaries, the SIMPLE algorithm is employed to couple the pressure and velocity, and time step size and number is selected reasonably. According to numerical simulation results, statistical analysis method, comparative analysis method and dimensionless analysis method is used to analyse central line velocity attenuation, velocity profile of different axial and radial position, flow pattern and vorticity characteristics, influence of different swirling velocity is also investigated, cutting capacity and influence factor of high pressure swirling water jet is evaluated. It is valuable for application of CFD in swirling waterjet field and helpful for understanding interior filed of swirling waterjet flow, meanwhile, this work could also provide reference for further investigation and application about swirling waterjet.