Numerical Simulation of Spray Break-Up from Cavitating Nozzle Flow by Combined Eulerian– Eulerian and Volume-of-Fluid Methods

The present study shows new results from the recently proposed method for numerical simulations of the spray break-up of cavitating liquid jets. A three-component system consisting of liquid, vapor and gas is applied for the volume-of-fluid simulation of the liquid disintegration in order to track the liquid–gas interface. To keep the numerical effort moderate, the liquid–vapor interface is not resolved by the computational grid, there mass and momentum transfer are described within the Eulerian-Eulerian framework. The numerical method is applied on a simplified injector-like geometry from the literature operated with gasoline at low pressure difference. For quantification of the detached spray ligaments, a new evaluation algorithm has been developed and implemented into the applied CFD code. It scans the liquid volume fraction field for separated ligaments, and determines their position, size and velocity. Additionally the ligament extensions along the principal axes of inertia are determined in order to evaluate the non-sphericity of each ligament after break-up. The presented simulation technique allows detailed numerical investigations of the spray formation process on the micro-scale by taking into account nozzle cavitation, turbulence and aerodynamic forces.