Characterization of the steady and unsteady spray structures of a liquid jet in supersonic crossflow

Abstract

Characterization of the spray resulting from a 1 mm diameter liquid ethanol jet injection into a supersonic air crossflow is presented. The isentropic Mach number at the injection location is 1.94, while the momentum flux ratio is varied between 3 and 13. Steady and unsteady components of the penetration depth are retrieved using backlit imaging perpendicular to the spray at a frame rate of 20 kHz, coupled with a telecentric lens to accommodate the test section's width and ensure equal magnification through the spray's width. Spray width at specific axial locations downstream of injection is measured by imaging Mie scattered light from a planar laser sheet directed perpendicular to the flow direction so that a cross section of the spray is recorded by a camera placed at a known angle between camera axis and flow direction.