Date of Award

December 2017

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Mechanical and Aerospace Engineering

Advisor(s)

Mark N. Glauser

Keywords

Aircraft, Jet, SERN, Supersonic, Turbulence

Subject Categories

Engineering

Abstract

For nearly 80 years, the jet engine has set the pace for aviation technology around the world. Complexity of design has compounded upon each iteration of nozzle development, while the rate of fundamental fluids knowledge struggles to keep up. The increase in velocities associated with supersonic jets, have exacerbated the need for flow physics research. Supersonic flight remains the standard for military aircraft and is being rediscovered for commercial use. With the addition of multiple streams, complex nozzle geometries, and airframe integration in modern aircraft, the flow physics rapidly become more difficult. As performance capabilities increase, so do the noise producing mechanisms and unsteady dynamics. This has prompted an experimental investigation into the flow field and turbulence quantities of a modern jet nozzle configuration.

A rectangular supersonic multi-stream nozzle with aft deck is characterized using time-resolved schlieren imaging, stereo PIV measurements, deck mounted pressure transducers, and far-field microphones. These experiments are performed at the Skytop Turbulence Laboratory at Syracuse University. LES data by The Ohio State University are paired with these experiments and give valuable insight into regions of the flow unable to be probed. By decomposing this complex flow field into two canonical flows, a supersonic rectangular nozzle and a sonic wall jet, a fundamental approach is taken to observe how these two jets interact.

Thorough investigations of the highly turbulent flow field are being performed. Current analytical techniques employed are statistical quantities, turbulence properties, and low-dimensional models. Results show a dominant high frequency structure that propagates through the entire field and is observable in all experimental methods. The structures emanate from the interaction point of the supersonic jet and sonic wall jet. Additionally, the propagation paths are directionally dependent. Further, spanwise PIV measurements observe the asymmetric nozzle to be relatively two-dimensional across half of the jet span.

An investigation into the effect of the aft deck has shown that the jet plume deflection depended on the aft deck length. This deflection is tied to separation and reattachment caused by reflecting oblique shocks. Additionally, low-dimensional models in the form of POD and DMD observe the most energetic and periodic structures in the turbulent flow field. Finally, these experimental results are paired with LES using data fusion techniques to form a more complete view of the flow. The comprehensive dataset will help validate computational models and create a basis for future SERN and aft deck designs.

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