Project overview

This project aims to develop tools to predict and mitigate high-amplitude acoustic tones, known as screech, in turbulent flows issuing from twin rectangular engines.

These tones are known to be deleterious to both personnel (leading to high levels of annoyance and potential hearing loss) and aircraft structure; due to its high amplitude and proximity to natural resonance frequency of some parts, structural failure often occurs as a result of screech. Screech is severely amplified with the presence of a second jet, deeming its mitigation a high priority in tactical aircraft.

Despite being a highly non-linear process, prediction tools based on the linearized Navier-Stokes equations have been successful in predicting several characteristics of screech in a myriad of jet geometries. Here, such an approach is used in association with extensive optical measurements to uncover the mechanism of tone generation and coupling in rectangular twin-jets. The same approach is used to propose nozzle modifications to suppress resonance in these flows, resulting in more silent aircraft and a lower structural failure rate.