Accession Number : ADA294574

Title :   Stream Breakup by Waves.

Descriptive Note : Final rept.,

Corporate Author : CALIFORNIA UNIV IRVINE COMBUSTION LAB

Personal Author(s) : Samuelsen, G. S. ; Ateshkadi, Arash

PDF Url : ADA294574

Report Date : APR 1995

Pagination or Media Count : 106

Abstract : An imaging technique is used to investigate the fluid dynamics associated with the breakup of a liquid jet by a passing transverse shock wave. This mechanism is believed to be a potential source of combustion instability in liquid propellant rocket engines. Combustion instability is caused by the release of heat in phase with a passing pressure disturbance. The jet/wave interaction causes rapid atomization and propellant redistribution, and enhances mixing, vaporization, and reaction rates. Knowledge of the breakup process aids in prediction of local heat release with respect to the passing wave and provides insight on its viability as a potential instability mechanism. The present shock tube study applies high-speed, high-resolution photography to explore the jet/wave interaction that might be experienced in a large scale liquid oxygen/hydrogen (LOX/H2) engine similar to the Space Shuttle Main Engine (SSME) or other such engines being considered for the next generation of launch systems. Fluid parameters deemed important were simulated as well as possible. Two types of wave induced breakup were examined: a constant velocity flow field (square wave) and an exponentially decaying velocity field (N-wave). Time resolved images of the jet/wave interaction indicate very rapid and fire atomization within 500 microns of impingement. Shock interaction with the primary atomization process produces a substantial change to the breakup mechanism and serves as a principal candidate for the promotion and acceleration of rocket engine instability. Results of the qualitative and quantitative study reveal that the step wave produces a long duration tangential and normal stress on the liquid column as compared to the N-wave. As a result, N-waves decelerate jet displacement and extend the jet breakup time.

Descriptors :   *SHOCK WAVES, *COMBUSTION STABILITY, *LIQUID ROCKET PROPELLANTS, *LIQUID JETS, *ATOMIZATION, DISTRIBUTION, INTERACTIONS, PARAMETERS, REACTION TIME, DISPLACEMENT, FLOW FIELDS, SPACE SHUTTLES, PHOTOGRAPHY, PRESSURE, LIQUID PROPELLANT ROCKET ENGINES, TRANSVERSE WAVES, FLUID DYNAMICS, INSTABILITY, VAPORIZATION, SHOCK TUBES, STEADY FLOW, SQUARE WAVES.

Subject Categories : Combustion and Ignition
      Astronautics

Distribution Statement : APPROVED FOR PUBLIC RELEASE