Date of Award

Summer 7-1-2022

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Mechanical and Aerospace Engineering

Advisor(s)

Glauser, Mark N.

Keywords

Flow Control, Multistream, Rectangular Jet, Supersonic

Subject Categories

Aerodynamics and Fluid Mechanics | Aerospace Engineering | Engineering | Mechanical Engineering

Abstract

Passive control techniques are applied experimentally to examine different aspects of a supersonic multistream rectangular nozzle representing a modern airframe-integrated variable cycle engine. The flow is comprised of a core stream (M = 1.6) and bypass (M = 1.0) that merge behind a splitter plate and exit through a Single Expansion Ramp Nozzle (SERN) onto an aft-deck. Previous efforts for the nominal nozzle configuration have shown that an instability initiated at the splitter plate trailing edge (SPTE) influences the effectiveness of the third stream as a barrier for the aft-deck and persists through the entire do- main due to its reaction with the shock train. To address this, passive flow con- trol was implemented by introducing sinusoidal spanwise modifications along the splitter plate edge. The SPTE was identified as the highest region of sensitivity via LES. Results on different spanwise wavenumbers indicate reduction of the dominating tone with increasing wavenumber. Additionally, the sinusoidal trailing edge induces streamwise vorticity, which enhances mixing between the two streams and breaks up the shed structures seen previously. A wavenumber corresponding to one simulated was tested experimentally via the use of simultaneous nearfield pressure and velocity in conjunction with farfield acoustics. Farfield acoustic measurements have confirmed the diminishment of the tone for the wavy SPTE. PIV and velocity profiles for mean fields revealed higher plume vectoring for the nominal aft-deck. The shear layers and the region along the aft-deck surface displayed significant enhancement of velocity variability through low order statistics. As a result of this increase, the POD modes werereordered for the wavy SPTE. Wavy modes had smaller spatial structures presented in lower modes, with increased energy content when compared to the same modes in the nominal flow.

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Open Access

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