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Research Papers: Gas Turbines: Aircraft Engine

Far-Field Noise Control in Supersonic Jets From Conical and Contoured Nozzles

[+] Author and Article Information
Jin-Hwa Kim, Martin Kearney-Fischer

Ohio State University, Columbus, OH 43235

Mo Samimy1

Ohio State University, Columbus, OH 43235samimy.1@osu.edu

Sivaram Gogineni

Spectral Energies, LLC, Dayton, OH 45431

1

Corresponding author.

J. Eng. Gas Turbines Power 133(8), 081201 (Apr 07, 2011) (9 pages) doi:10.1115/1.4002811 History: Received June 01, 2010; Revised June 01, 2010; Published April 07, 2011; Online April 07, 2011

Abstract

Plasma actuators are used to control far-field noise in Mach 1.65 jets from contoured and conical supersonic axisymmetric nozzles (henceforth, contoured and conical jets, respectively). The contoured nozzle is designed using the method of characteristics for a shock-free jet. The conical nozzle has converging and diverging conical sections with a sharp throat. Eight plasma actuators, distributed uniformly around the nozzle exit, are used and the jet is forced with azimuthal modes $(m)$ 0–3 and $±4$ and forcing Strouhal numbers ranging from 0.09 to 4.0. The far-field acoustic noise is measured by a linear microphone array covering polar angles from 25 deg to 80 deg relative to the jet axis. In both jets, the lower forcing azimuthal modes ($m=0$ and 1) are less effective than the higher modes ($m=2$, 3, and $±4$), which have similar levels of overall sound pressure level (OASPL) reduction. At shallow angles relative to the jet axis, the reduction in OASPL is about 1.6–1.8 dB at low forcing Strouhal numbers in both jets at the most effective forcing mode of $m=3$. However, the OASPL in the sideline direction is only slightly increased (about 1 dB) for both the contoured and conical jets at $m=3$. The reduction at shallow polar angles is related to the decrease in the peak mixing noise level in both jets. The range of forcing Strouhal numbers providing significant noise reduction and the range of polar angles over which the noise is reduced are both much larger in the conical jet compared with the contoured jet. The screech tones are also reduced or suppressed – most likely due to weakening of naturally occurring structures by forcing.

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Figures

Figure 1

Cross section of contoured (a) and conical (b) nozzles

Figure 2

Schematic of linear microphone array

Figure 3

Schematic of PIV setup

Figure 4

Far-field baseline spectra at 30 deg (a) and 80 deg (b) polar angles for contoured and conical Mach 1.65 jets

Figure 5

Time-averaged schlieren images for the contoured (a) and conical (b) baseline jets

Figure 6

Inner wall pressure profiles for the Mach 1.65 contoured and conical nozzles at the design condition

Figure 7

Ensemble-averaged velocity contours (contoured (a) and conical (b) jets) and (contoured (c) and conical (d) jets) Galilean streamlines

Figure 8

Change in OASPL in the contoured jet for m=0 (a) and 3 (b)

Figure 9

Change in OASPL in the conical jet for m=0 (a) and 3 (b)

Figure 10

ΔOASPL in the peak reduction angle for the contoured jet at 30 deg (a) and the conical jet at 40 deg (b)

Figure 11

Spectra at StDF=0.71 and at m=3 in the contoured jet

Figure 12

Spectra at StDF=1.5 and at m=3 in the conical jet

Figure 13

Spectra at ϕ=30 deg and at m=3 in the contoured jet

Figure 14

Spectra at ϕ=40 deg and at m=3 in the conical jet

Figure 15

Far-field spectra at ϕ=80 deg and at m=3 in the conical jet

Figure 16

Galilean streamlines superimposed on conditionally averaged streamwise velocity at m=3 for the conical jet and at StDF=0.18 (a), 0.7 (b), and 3.0 (c)

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