Noise predictions for high subsonic single and dual-stream jets in flight

Swati Saxena, Philip John Morris

Research output: Chapter in Book/Report/Conference proceedingConference contribution

2 Scopus citations

Abstract

This paper presents numerical jet noise predictions for single and dual-stream jets in ight. The goal of the present work is to study flight effects in high subsonic Mach number jets. To perform the turbulent flow simulation, a parallel unsteady Reynolds-averaged Navier-Stokes (URANS)-Large Eddy Simulation (LES) solver is used. A modified Detached Eddy Simulation (DES) model is used to generate the turbulent flow downstream of the nozzle. A structured multi-block grid approach is used to attain a reasonable grid resolution with high order spatial discretization. Solutions of the Ffowcs Williams and Hawkings (FW- H) equation are used to predict the jet noise spectra at far-field observer locations. The flow parameters and the noise prediction results are compared with PIV and microphone measurements. The computational domains have grid points ranging from 5 million to 9 million and include 14 to 26 blocks. A baseline single stream convergent nozzle and a dual-stream coaxial convergent nozzle are used for the flow and noise analysis. Calculations for the convergent nozzle are performed at a high subsonic jet Mach number of Mj = 0.9. The parallel flow constitutes the flght effect which is simulated with a co-flow Mach number, Mcf varying from 0 to 0.28. The statistical properties of the turbulence and heated jet effects (TTR = 2.7) are studied and related to the noise characteristics of the jet. Both flow and noise predictions show good agreement with the PIV and microphone measurements. The flight velocity exponent, m is calculated from the noise reduction in overall sound pressure levels and relative velocity (10Log10[Vj=(Vj - Vcf)]) at all observer angles. There is a distinct variation of the flight velocity exponent with angle: it increases gradually from 3.0 at lower polar angles (relative to the inlet) ~ 50 to 105° to about 6.0 at ~ 110 to 150°. A scaling method using the exponent is shown to provide good collapse of the spectra obtained in forward flight.The coaxial nozzle is a Boeing designed convergent nozzle with an area ratio of As=Ap = 3.0, where the primary nozzle extends beyond the secondary nozzle. This conflguration is representative of the large turbofan engines in commercial service. The jet flow conditions are: Mpj = 0.9 and Msj = 0.95 with heated core flow, TTRp = 2.26 and unheated fan flow. Only one co-flow case with Mcf = 0.2 is used. The subscripts p and s represent the primary (core) nozzle and the secondary (fan) nozzle, respectively. The preliminary flight effect findings for the dual-stream jet suggest a different trend of ight velocity exponentas compared to single stream jet, though only limited predictions are available.

Original languageEnglish (US)
Title of host publication18th AIAA/CEAS Aeroacoustics Conference (33rd AIAA Aeroacoustics Conference)
StatePublished - 2012
Event18th AIAA/CEAS Aeroacoustics Conference 2012 (33rd AIAA Aeroacoustics Conference) - , United States
Duration: Jun 4 2012Jun 6 2012

Other

Other18th AIAA/CEAS Aeroacoustics Conference 2012 (33rd AIAA Aeroacoustics Conference)
CountryUnited States
Period6/4/126/6/12

All Science Journal Classification (ASJC) codes

  • Aerospace Engineering
  • Mechanical Engineering
  • Acoustics and Ultrasonics

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  • Cite this

    Saxena, S., & Morris, P. J. (2012). Noise predictions for high subsonic single and dual-stream jets in flight. In 18th AIAA/CEAS Aeroacoustics Conference (33rd AIAA Aeroacoustics Conference)