STUDY ON THE EFFECT OF THE PRESENCE OF FUEL VAPOR IN THE SURROUNDING GAS ON THE MIXING CONTROLLED VAPORIZATION OF FUEL SPRAY

In different combustion devices, liquid fuel is injected inside the combustion chamber. The liquid fuel spray atomizes, vaporizes, and mixes with the surrounding gas before combustion. The vaporization rate of the injected fuel is very important because it controls the air-fuel mixing and finally the combustion rate. Similar to droplet vaporization, the concentration of fuel vapor in the surrounding gas influences the spray vaporization process. It changes the maximum liquid phase penetration or liquid length (LL) of a vaporizing spray. Hence the liquid length model should consider the ambient fuel concentration effect, but has been ignored up until now. The present work studies the liquid lengths of vaporizing sprays at different fuel vapor concentrations in the surrounding gas. The effects of ambient fuel concentration on heating and vaporization of the spray are analyzed in the context of a mixing controlled vaporization model. The results shows that the fuel concentration in the surrounding gas changes the maximum liquid phase fuel temperature and the specific energy required for vaporization. It is observed that as the ambient fuel concentration effect is ignored in the existing mixing controlled model, it fails to predict liquid lengths when the surrounding gas is mixed with fuel vapor. A modified model is presented where the mass fraction of fuel vapor in the surrounding gas is included in the model. The modified model is able to predict the LL values more accurately when the surrounding gas is mixed with fuel vapor.