Numerical Study for Free-Stream Turbulence Effects on a Single Droplet Vaporization

This investigation reports on the study of the ambient turbulent effects on the droplet vaporization in the fuel spray combustion. For tractability, this discussion considers a single droplet in an infinite turbulent flow.

In this numerical study, the low-Reynolds-number version of k- ε turbulence model was used to represent the turbulence effects. The set of two-dimensional conservation equations which describe the transport phenomena in turbulent flow using the mean flow quantities including the droplet internal laminar motion, are solved numerically with the finite difference procedure of Patankar(SIMPLER). The evaluation of the computational model is provided by two limiting cases: turbulent flow over the solid sphere and the laminar flow over a liquid drop.

The results show that the turbulence effects are noticeable for the vaporization at high turbulence intensity (10-50%) which is encountered in a typical spray. The magnitude of turbulence effects mainly depends on the turbulent intensity. These effects are not sensitive to the Reynolds number in the range of 50 to 200, ambient temperature in the range of 700 to 1000° K and the volatility.