ID 88

Three-dimensional SPH simulation of a twin-fluid atomizer operating at high pressure

 

Abstract:

In the context of biofuel production, a twin-fluid atomizer is investigated by the means of the Weakly-Compressible Smoothed Particle Hydrodynamics (WCSPH) method. This configuration consists of a round liquid jet discharging at low velocity into a quiescent cavity. The liquid is atomized by a high-speed turbulent co-flow. This configuration has been studied experimentally as well. In order to reflect the experimental conditions, the liquid is a mixture of Glycerol and water and a constant viscosity is set to 200 mPa s. The ambient pressure is 11 bar and the gas velocity is 58.3 m/s, leading to a gas Reynolds number of 137 000 and a Weber number of 1375. The three-dimensional numerical domain consists of the twin-fluid nozzle and a cavity of 30 mm length and 17.4 mm diameter. The spatial resolution is 33 µm, which leads to 208 million of particles. The simulation is run for 45 ms of physical time using 2000 CPU. The results show that the fiber-mode breakup is well captured by the method. The shape and the dynamics of the fragmented liquid lumps are in very good qualitative agreement with the experimental observations. Further quantitative analyses are performed in terms of time average of the liquid phase, and time evolution of the spray characteristics at the exit of the cavity. Finally, due to the Lagrangian nature of the SPH method, the breakup sequence of each liquid elements can be monitored and collected. Hence, the fragmentation spectrum of this configuration is also presented