Abstract

The instability and subsequent atomization of a viscous liquid jet emanated into a high-pressure gaseous
surrounding is studied both computationally and experimentally. Liquid water issued into nitrogen gas at
elevated pressures is used to simulate the flow conditions in a coaxial shear injector element relevant to liquid
propellant rocket engines. The theoretical analysis is based on a simplified mathematical formulation of the
continuity and momentum equations in their conservative form. Numerical solutions of the governing equations
subject to appropriate initial and boundary conditions are obtained via a robust finite difference scheme. The
computations yield real-time evolution and subsequent breakup characteristics of the liquid jet. The experimental
investigation utilizes a digital imaging technique to measure resultant drop sizes. Data were collected for liquid
Reynolds number between 2,500 and 25,000, aerodynamic Weber number range of 50-500 and ambient gas
pressures from 150 to 1200 psia. Comparison of the model predictions and experimental data for drop sizes at
gas pressures of 150 and 300 psia reveal satisfactory agreement particularly for lower values of investigated
Weber number. The present model is intended as a component of a practical tool to facilitate design and
optimization of coaxial shear atomizers.

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