Work

Acoustic flow resonances in installed rectangular jets

Year: 2024

Type: article

Abstract: Zonal Large Eddy Simulations (LES) of installed rectangular jet flows are performed for conditions of the Central Institute for Aviation Motors (CIAM) experiment. For far-field noise predictions, unsteady flow solutions are coupled with the permeable formulation of the Ffowcs Williams and Hawkings method. The resulting noise predictions are compared with the acoustic measurements of the CIAM experiment, which showed prominent tones typical of acoustic-flow interactions. Good agreement between the modelling and the experiment is demonstrated for the frequency and amplitude of the main tone for a range of observer polar angles. The predicted Over All Sound Pressure Levels (OASPL) show a 1-2dB agreement with the experiment for most observer angles. For cross-validation, acoustic measurements in the CIAM acoustic facility obtained from replacing the rectangular nozzle exhaust together with the embodiment by an isolated round nozzle are compared with predictions of the empirical sJet model calibrated on the NASA (Small Hot Jet Acoustic Rig) SHJAR jet noise database. Spectral and conditional averaging analysis methods are applied to elucidate mechanisms of the acoustic-flow resonance in the installed rectangular jet flow. To investigate the acoustic reflections from the edges of the jet embodiment geometry, several modifications of the baseline rectangular nozzle are considered, such as introducing chevron-like lobes and cuts on the trailing edges of the side walls as well as smoothing the sharp corner points of the wall edges. Following a series of Zonal LES runs with the modified installed nozzle geometries, a tone-less modification of the original installed nozzle was obtained, which shows a significant reduction of noise levels in comparison with the baseline case. The resulting tone-less jet flow is analysed using the conditional averaging method to obtain insights into effective noise sources.

Source: Journal of Sound and Vibration

DOI: 10.1016/j.jsv.2024.118786

Authors: V.А. Shorstov, S.А. Каrabasov, V.Е. Маkarov, А.К. Мironov, V. Gryazev

Institutions: Baranov Central Institute of Aviation Motor Development, Queen Mary University of London, Brunel University of London

Language: English

Topic: Aerodynamics and Acoustics in Jet Flows

Subfield: Aerospace Engineering

Field: Engineering

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $4,070

Funder: Horizon 2020 Framework Programme