The Effect of Weber Number on Spray and Vaporization Characteristics of Liquid Jets Injected in Air Crossflow

Abstract

This paper details a numerical investigation conducted to systematically evaluate the effects of aerodynamic Weber number, in the range from 68 to 136, on spray characteristics and gaseous fluid dynamics when liquid jets are injected in high-temperature air crossflow. The momentum flux ratio and air temperature for all the cases studied in this research effort are 9 and 573 K, respectively. The computations are conducted using an Eulerian–Lagrangian framework, where the gas phase is modeled by the compressible form of the Navier–Stokes equations and the liquid phase is treated in the Lagrangian frame with appropriate models to account for jet injection and breakup phenomena. A modified version of two-way coupling, which takes into account the finite size of the dispersed phase, is used to account for the exchange of mass, momentum, energy and species between the two phases. Turbulence closure is achieved using the large eddy simulation technique. As a first step, the framework is validated against measurements for non-vaporizing and vaporizing conditions—our results agree well with experimental data. Next, three computations in the range of Weber numbers mentioned above are conducted—the effect of Weber number is quantified in terms of the spatiotemporal evolution of the mass fraction of the vaporized liquid, detailed distributions of droplet sizes, their velocities, and volumetric fluxes. It is found that with an increase in the Weber number, the droplet sizes and the penetration depth monotonically decreased. As a result, at higher Weber number conditions, the vaporized liquid in the domain increases due to the overall enhancement in the effective surface area of the liquid phase.