Date of Award

6-26-2026

Date Published

July 2026

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Mechanical and Aerospace Engineering

Advisor(s)

Kasey Laurent

Keywords

Acoustics;Flow control;Rectangular Nozzle;Supersonic;Turbulence;Vortex Shedding

Abstract

Within an experimental rectangular dual-stream supersonic nozzle, a vortex-shedding instability forms at the blunt trailing edge of the splitter plate separating the Mach = 1.23 core flow and Mach = 1.0 bypass flow, with the combined jet further expanded to Mach = 1.6. This instability generates large coherent vortical structures that interact with the downstream recompression shock, inducing oscillations and producing high-frequency acoustic radiation that dominates both the near- and far-field. Active and passive control techniques are applied to suppress the formation of energetic, periodic vortex shedding and thus reduce or eliminate its effects on the flow field. Three control methods are applied to the splitter plate trailing edge: a passive geometric modification, a passive bleed configuration, and an active steady blowing jet array. Far-field acoustic measurements taken within an anechoic chamber, high-speed schlieren and shadowgraph imaging, and scanning stereoscopic particle image velocimetry are used to characterize the vortex shedding and enable comparison of the controlled and baseline flow fields. The interaction between vortex shedding and the downstream shock structure is experimentally identified as the source of shock flapping, which is shown to be the primary mechanism responsible for the observed high-frequency acoustic radiation. This mechanism is proposed to represent a narrowband shock-associated noise process, constituting a limiting case of broadband shock-associated noise. All three control strategies are effective at suppressing the formation of the coherent shedding instability, instead redistributing its energy across a broader range of frequencies. As a result, the far-field acoustic signature is substantially reduced, the shock-shear-layer system of the nozzle is stabilized, and the downstream jet plume development is altered. These results establish a direct experimental link between internal vortex-shedding dynamics, shock motion, and radiated noise in a dual-stream supersonic nozzle, and demonstrate viable strategies for mitigating these effects.

Access

Open Access

Download

Share

COinS