Simulation and Optical Diagnostics for Internal Combustion Engines

Abstract

Enhancing the predictability of diesel spray numerical simulation, a droplet breakup model has been developed and optimized under non-evaporative diesel spray with a large-eddy simulation. In the spray simulation community, the model called Kelvin–Helmholtz and Rayleigh–Taylor model has been widely used even nowadays, both of which are modeled for high Weber number conditions. While upstream region of spray considers as high Weber number thanks to high injection pressure, downstream of the spray represents by low Weber number region. In this study, a hybrid breakup model which combines the Kelvin–Helmholtz and modified Taylor analogy breakup has been proposed. The Kelvin–Helmholtz and modified Taylor analogy breakup models are used to the primary and secondary breakup models, respectively. For validating the breakup model, one of the unique optical diagnostics techniques has been introduced to capture both macroscopic and microscopic spray characteristics at the same time. The system called super high spatial resolution photography lens is able to capture sufficient area of the spray with having a 5 µm spatial resolution. Spray simulations under non-evaporative condition were performed to validate the Kelvin–Helmholtz–modified Taylor analogy breakup model. It is found that the simulation results of Kelvin–Helmholtz–Modified Taylor analogy breakup are in good agreement with experimental measurements of droplet distribution under non-evaporative spray.