Understanding supersonic combustion with numerical simulation

The atomization and combustion of liquid fuel in aircraft engines are important processes to consider during engine design. As flight speed increases, researchers must understand these processes in supersonic airflow.

Hung et al. used a method to numerically simulate the atomization of a liquid transverse jet in supersonic gas crossflow, which has not been extensively studied before.

The numerical simulation showed atomization occurred in four separate stages, and the supersonic airflow caused a shock wave in front of the liquid jet. It also revealed the importance of two types of instability during atomization. They found Plateau-Rayleigh instability broke small pieces and ligaments of the jet into tiny droplets, whereas Kelvin-Helmholtz instability deformed the liquid surface and column.

The simulation method used multiple approaches. Weighted essentially nonoscillatory schemes and the Harten-Lax-van Leer Contact approximate Riemann solver simulated the gas flows, and the Chorin projection method simulated the liquid flow. The volume of fluid method simulated the motion of the sharp interface between gas and liquid.

The authors calculated Mach numbers in the gas crossflow and examined how it affected atomization. A higher Mach number increased the number of droplets, enhancing atomization. Increasing the Mach number also corresponded with decreasing shock wave standoff distance and increasing deformation of the interface on the liquid jet’s head.

“The present study will enhance understanding on the issue of supersonic combustion and provide a numerical method for related future research,” said author Xin Zhao.

Next, the authors will study more realistic supersonic combustion by adding the fuel evaporation model and the combustion model to their method.

Source: “Numerical simulation of the atomization of liquid transverse jet in supersonic airflow,” by Junkai Huang, Xin Zhao, and Hao Jiang, Physics of Fluids (2021). The article can be accessed at https://aip.scitation.org/doi/full/10.1063/5.0050520 .

This paper is part of the Selected Papers from the 11th National Congress on Fluid Mechanics of China Collection, learn more here .