Development and assessment of an improved droplet breakup model for numerical simulation of spray in a turbulent flow field

Abstract

The present article proposes an improved spray breakup model considering the effect of carrier phase turbulence on both the critical Weber number and the breakup rate. For this aim, the effective surface tension as a new concept was introduced to combine the effects of turbulent and aerodynamic induced breakup. A simple analytical expression has been developed for calculating the effective surface tension according to the local turbulence characteristics of the carrier phase. Afterwards, the proposed effective surface tension was used for calculating the critical Weber number in turbulent flow fields and an excellent agreement was shown in comparison with the available experimental data. In the following, an improved secondary atomization model was developed by implementation of the effective surface tension in the classic Pilch-Erdman model. To assess the capabilities of the new breakup model, it was implemented into a CFD code and the results compared with experimental data and those obtained by the previous breakup models. The present model showed a better agreement with experimental data in predicting the spray tip penetration length and local Sauter mean diameter (SMD). It is concluded that the improved model is effectively more reliable for simulation of spray droplet breakup in turbulent gaseous environments.