Effect of Physical Properties on Spray Models

In this work the modeling aspects of fuel vaporization are studied. To start with, the effects of vaporization model on engine simulations are studied. This is done by using two different fuel surrogates. Next a set of non-reacting spray simulations were performed under different ambient and operating conditions and for two different fuels. This was done for spray model validation and to look at the effect of vaporization model on liquid penetration length. Following an observed discrepancy in one of the spray cases, effect of ambient temperature on liquid length, two sensitivity analyses were performed. These analyses take into account the effects of each spray-sub model on vaporization and effects of spray breakup constants on liquid penetration. Using the results from the sensitivity analyses and linearized stability theory an empirical correction factor was developed to correct the spray behavior at low ambient temperatures. This factor corrects the Rayleigh-Taylor breakup time based on the fuel viscosity and empirical data for liquid length. To validate the correction factor a set of reacting and non-reacting cases were run with different fuels and it was observed that with the empirical correlation, the results are in good agreement with experimental data, which is encouraging.