Effects of Periodic Atomization on Combustion Instability in Liquid-Fueled Propulsion Systems

This paper examines the specific role that atomization may play in combustion instability in liquid rocket engines. The effects of mean drop size, drop-size distribution, and atomization periodicity are examined explicitly with a combustion response model, whose results indicate that all of these effects are important. It is shown that periodic atomization results in large variations in the magnitude of the pressure response wben the atomization frequency is within a factor of 10 of the acoustic oscillation frequency. These results are consistent with an explanation of an empirical stability correlation, whereby the nonuniform and unsteady production of drops is a controlling factor in the growth of combustion instabilities. Experimental results from a subscale rocket combustor that support the importance of periodic atomization are also presented. (Author)