Experimental study of mixing layer in a closed compound channel

2013 ◽  
Vol 36 (2) ◽  
pp. 411-420 ◽  
Author(s):  
Jhon Goulart ◽  
Luciano Noleto ◽  
Sérgio V. Möller
Keyword(s):  
Experimental Study ◽  
Mixing Layer ◽  
Compound Channel

scholarly journals NUMERICAL ANALYSIS OF DEVELOPING TURBULENT FLOW IN A CLOSED COMPOUND CHANNEL

2011 ◽  
Vol 10 (1-2) ◽  
pp. 81
Author(s):  
S. I. S. Souza ◽  
J. N. V. Goulart
Keyword(s):  
Mixing Layer ◽  
Flow Instabilities ◽  
Navier Stokes ◽  
Compound Channel ◽  
Narrow Gap ◽  
Layer Formation ◽  
Velocity Difference ◽  
Large Structures ◽  
Ansys Cfx ◽  
Reynolds Average

The study of turbulence characteristics in compound channels is still focus of attention. A lot of experimental results have been produced. Main results have revealed a mixing layer formation between main subchannel and the gap region, implying the flow might be ruled by local scales. The outcomes have pointed to the instabilities of mixing layer are responsible for large structures formation between main channel and narrow gap. Furthermore, the periodical behavior of these structures seems to be ruled by mean mixing layer characteristics, as velocity difference, velocity of convection and mixing layer thickness. By using ANSYS-CFX-12, with unsteady Reynolds Average Navier-Stokes and as turbulence model Spalart-Allmaras (SA), a compound channel was studied. Numerical results predicted velocity profile with high vorticity peaks and flow instabilities starting at L/Dh = 15.

An experimental study of the structure of a compressible, reacting mixing layer

1993 ◽  
Author(s):  
M. MILLER ◽  
T. ISLAND ◽  
B. YIP ◽  
C. BOWMAN ◽  
M. MUNGAL ◽  
...  
Keyword(s):  
Experimental Study ◽  
Mixing Layer

scholarly journals EXPERIMENTAL STUDY OF FLOW STRUCTURES IN A DOUBLE MEANDERING COMPOUND CHANNEL

2000 ◽  
Vol 44 ◽  
pp. 873-878 ◽  
Author(s):  
Kenichiio KOBAYASHI ◽  
Nobuyuki TAMAI ◽  
G.M.Tarekul ISlam
Keyword(s):  
Experimental Study ◽  
Flow Structures ◽  
Compound Channel

Experimental study on evolution of joint velocity PDF in planar mixing layer

2010 ◽  
Vol 34 (8) ◽  
pp. 1122-1132 ◽  
Author(s):  
Chiuan-Ting Li ◽  
Keh-Chin Chang ◽  
Muh-Rong Wang
Keyword(s):  
Experimental Study ◽  
Mixing Layer ◽  
Joint Velocity

Experimental Study on a Notched Nozzle for Jet Noise Reduction

2011 ◽  
Author(s):  
T. Ishii ◽  
H. Oinuma ◽  
K. Nagai ◽  
N. Tanaka ◽  
Y. Oba ◽  
...  
Keyword(s):  
Experimental Study ◽  
Noise Reduction ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Mixing Layer ◽  
Jet Noise ◽  
Computational Prediction ◽  
Pressure Level ◽  
Far Field ◽  
Noise Sources

This paper describes an experimental study on a notched nozzle for jet noise reduction. The notch, a tiny tetrahedral dent formed at the edge of a nozzle, is expected to enhance mixing within a limited region downstream of the nozzle. The enhanced mixing leads to the suppression of broadband peak components of jet noise with little effect on the engine performance. To investigate the noise reduction performances of a six-notch nozzle, a series of experiments have been performed at an outdoor test site. Tests on the engine include acoustic measurement in the far field to evaluate the noise reduction level with and without the notched nozzle, and pressure measurement near the jet plume to obtain information on noise sources. The far-field measurement indicated the noise reduction by as much as 3 dB in terms of overall sound pressure level in the rear direction of the engine. The use of the six-notch nozzle though decreased the noise-benefit in the side direction. Experimental data indicate that the high-frequency components deteriorate the noise reduction performance at wider angles of radiation. Although the increase in noise is partly because of the increase in velocity, the penetration of the notches into the jet plume is attributed to the increase in sound pressure level in higher frequencies. The results of near-field measurement suggest that an additional sound source appears up to x/D = 4 due to the notches. In addition, the total pressure maps downstream of the nozzle edge, obtained using a pressure rake, show that the notched nozzle deforms the shape of the mixing layer, causing it to become wavy within a limited distance from the nozzle. This deformation of the mixing layer implies strong vortex shedding and thus additional noise sources. To improve the noise characteristics, we proposed a revised version of the nozzle on the basis of a computational prediction, which contained 18 notches that were smaller than those in the 6-notched nozzle. Ongoing tests indicate greater noise reduction in agreement with the computational prediction.

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