M.S. Thesis Presentation by Lance Christopher Elwell

(Drs. Minami Yoda and Said Abdel-Khalik, co-advisors)

"Dynamics of Stationary and Obliquely Oscillating Free Plane Jets"


Protecting the first walls of inertial fusion energy power plant chambers from X-ray and neutron damage is crucial for developing commercial fusion energy.  By absorbing the X-rays and ions, and attenuating the neutrons from the fusion event which may damage solid surfaces, thick liquid offers a possible method to significantly decrease chamber size and increase working lifetime, thereby reducing capital costs.  Arrays of obliquely oscillated turbulent free plane jets, which provide a protective pocket surrounding the fusion event, are a fundamental component of the HYLIFE-II thick liquid protection fusion power plant design.  This Masterís thesis involves an experimental investigation of this turbulent free shear flow, which cannot at present be computationally analyzed with confidence.  This project uses flow visualization to determine the jet mean spread rate and to document how various oscillation conditions will affect the jet trajectory.

The Georgia Tech Oscillating Jet Facility is used to study stationary and oscillating plane jets of water issuing from two nozzles, one with a rectangular cross-section of dimensions 1 cm ? 10 cm and one with a cross-section of 0.5 cm x 5 cm, for Reynolds numbers based on jet thickness up to 3.8 x 104.  Jets oscillated at amplitudes from 1 mm to 5 mm, along angles (measured from the longitudinal centerline of the nozzle) from 0o to 90o, and at normalized frequencies (Strouhal number based on jet thickness) from 0.008 to 0.03 are studied. The jet spread rate and trajectory are determined by illuminating the jet with a flashlamp and filming it at 30 Hz using a CCD camera.  A theoretical model of oscillated jet trajectories is developed and tested using the data.  This research will contribute to the development of thick liquid protection for fusion energy power plants by establishing criteria for the oscillation parameters and jet nozzle spacings required for various protective pocket designs.