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This paper describes numerical implementation of a newly developed hybrid model, T-bbb/7'-TAB, into an existing computational fluid dynamics (CFD) program for primary and secondary breakup simulation of liquid jet atomization. This model extend two widely used models, the Kelvin-Helmholtz (KH) instability of Reitz (blob model) and the Taylor-Analogy-Breakup (TAB) secondary droplet breakup by O'Rourke and Amsden to include turbulence effects. In the primary breakup model, the level of the turbulence effect on the liquid breakup depends on the characteristic scales and the initial flow conditions. For the secondary breakup, a n additional turbulence force acted on parent drops is modeled and integrated into the TAB governing equation. Several assessment studies are presented and the results indicate that the existing KH and TAB models tend to under-predict the product drop size and spray angle, while the current model provides superior results when compared with the measured data.

A new approach to account for finite thermal conductivity and turbulence effects within atomizing droplets of an evaporating spray is presented in this paper. The model is an extension of the T-blob and T-TAB atomizatiodspray model of Trinh and Chen [9]. This finite conductivity model is based on the two-temperature film theory in which the turbulence characteristics of the droplet are used to estimate the effective thermal diffusivity for the liquid-side film thickness. Both one-way and two-way soupled calculations were performed to investigate the performance cf this model against the published experimental data.

Understanding injector dynamics in the presence of strong pressure pulsations in Liquid Fueled Rocket Engines (LFRE) is important due to its strong association with the combustion instability phenomena. Lack of generators of strong periodical pulsations, particularly in the high frequency range, is problematic. To overcome this deficiency, a hydro-mechanical pulsator has been built to generate controlled periodic pressure oscillation, which simulates pressure pulsations in the feed lines of rocket motor injector systems. The present numerical analysis effort utilizes the unsteady Reynolds Averaged Navier-Stokes (URANS) approach, to model the pulsating turbulent flow inside the hydro-mechanical pulsator as a preliminary design study to estimate optimum operating conditions for the proposed experimental study. Numerical results obtained from the study using sliding/deforming grids coupled with a two-layer low-Reynolds number RNG k-ε model indicated that the form of pulsation could be controlled based on the geometry of the orifices of the rotating valve in order to define its main parameters, and in the determination of the optimum geometry for obtaining a sinusoidal harmonic response. The results of the computations to evaluate the effect of varying mass flow rates to examine the influence of change in amplitude and phase characteristics of standard injectors on the boundaries, frequencies and amplitude of high frequency combustion instability are presented in the paper.

This paper describes numerical implementation of a newly developed hybrid model, T-bbb/7'-TAB, into an existing computational fluid dynamics (CFD) program for primary and secondary breakup simulation of liquid jet atomization. This model extend two widely used models, the Kelvin-Helmholtz (KH) instability of Reitz (blob model) and the Taylor-Analogy-Breakup (TAB) secondary droplet breakup by O'Rourke and Amsden to include turbulence effects. In the primary breakup model, the level of the turbulence effect on the liquid breakup depends on the characteristic scales and the initial flow conditions. For the secondary breakup, a n additional turbulence force acted on parent drops is modeled and integrated into the TAB governing equation. Several assessment studies are presented and the results indicate that the existing KH and TAB models tend to under-predict the product drop size and spray angle, while the current model provides superior results when compared with the measured data.