Influence of a Hemispherical Noise Reduction Reflector on Transonic Jet Flows

Abstract

High pressure gas venting operations, known as blowdowns, produce significant noise. The simplest means of reducing blowdown noise is to reduce the jet velocity, however, this is often infeasible and/or undesirable in practise. Therefore, the capacity to design devices which provide noise abatement without significantly influencing venting velocities, is of practical interest. One device which has shown some potential for noise abatement is a hemispherical noise reduction reflector, however the influence of these devices on the jet velocity is unknown. Therefore, the present study aims to experimentally investigate the influence of hemispherical noise reduction reflectors on transonic jet flows. Flow measurements found the addition of a reflector did not significantly influence the resulting jet, beyond a slight increase in jet spreading, and therefore a slight reduction in peak velocity as the jet dissipates downstream, attributed to reduced flow entrainment.

A Critical Review of Supersonic Flow Control for High-Speed Applications

“…Various researchers have presented computational methods [65,66] with large-eddy simulations [67][68][69][70][71], high fidelity simulations [72] and 3D simulation [73]. The noise reduction of supersonic jets by nozzle trailing-edge changes was investigated experimentally [74], and hemispherical noise reduction reflectors on transonic jet flows [75] were conducted. Different injection sites, angles, and circumstances were also investigated, resulting in distinct acoustic behavior and flow-field changes [76].…”