Simulations of Plain-Orifice Injection of Gelled Propellants Under Manifold Crossflow Conditions

Abstract

Unsteady Navier–Stokes simulations are used to study the static and dynamic discharge characteristics of shear-thinning fluids passing through plain-orifice atomizers fed by a crossflow. The crossflow velocity is varied to assess implications of feeding fluid in a multi-element injector fed from a common manifold. Large and distinct horseshoe vortices are periodically generated near the inlet lip and convected along the length of the orifice passage. As these and other vortical structures pass through the orifice exit plane, they create small and distinct mass-flow pulsations. These pulsations are characterized for a variety of orifice length-to-diameter ratios, Reynolds numbers, manifold crossflow velocities, and fluid rheologies. Using candidate gels as testing fluids, it is typically observed under the unsteady flow conditions that discharge coefficient ranges from 0.5 to 0.6, Strouhal numbers are around 0.3, and oscillation magnitudes are less than 5% of averaged discharge coefficient.