Split Stream Flow Past a Blunt Trailing Edge with Application to Combustion Instabilities
In shear coaxial injectors, commonly used for cryogenic liquid rocket engines, propellants traveling at different velocities are separated by the inner jet post before they come into contact with each other, mix, and combust. Knowing how the fluids mix and how susceptible they are to hydrodynamic instabilities is paramount for a successful liquid rocket engine. In this study, the wake behind a blunt trailing edge of a long plate, similar to an unwrapped coaxial injector, was studied in a water tunnel. Two fluid streams of different velocities were introduced on opposite sides of the plate. PIV was used to visualize and determine the influence of the velocity ratio of the split stream on the wake behavior. Measurements of the vortex shedding frequency were taken at various velocity ratios and compared with well characterized cases with a uniform free stream. Operating conditions ranged from Reynolds number 6,000 to 22,000 and velocity ratios 0.30 to 1.00.
© 2012 American Institute of Aeronautics and Astronautics. The assistance of the Mechanical Engineering Shop at Caltech and undergraduate and graduate students of Caltech is gratefully acknowledged. The work was supported by the Air Force Research Laboratory, Lester Lees Aeronautics SURF Fellowship, Student Faculty Programs at Caltech, and Graduate Aerospace Laboratories at Caltech.
Accepted Version - TianAIAA2012.pdf