NUMERICAL MODELING FOR PRIMARY ATOMIZATION OF LIQUID JETS

In the proposed numerical model for primary atomization, surface-wave dispersion equations are solved in conjunction with the jet-embedding technique of solving mean flow equations of a liquid jet. Two types of wave models, namely linear and approximate nonlinear models, have been considered. In each case, the dispersion equation is solved over the whole wavelength spectrum. This enables the prediction of drop sizes, frequency, and liquid mass breakup rates from the first principles. Presently, the surrounding gas phase motion is prescribed; in the future, it will be computed simultaneously with the liquid surface and jet equations. The present model has been applied to several low-speed and high-speed jets. For low-speed water jets, predicted intact liquid core lengths and wave growth rates are in excellent agreement with available data. For the high-speed case (the liquid oxygen/gas hydrogen coaxial injection element of the Space Shuttle main engine preburner), predicted drop sizes and liquid breakup rates are in good agreement with the results of the coaxial injection combustion model, which have been calibrated against measured data. The present model limitations and possible extensions are also discussed in this paper.