Near and Far-Field Investigations of Supersonic Jet Noise Predictions Using a Coupled LES and FW-H Equation Method

2011 ◽  
Author(s):  
James P. Erwin ◽  
Neeraj Sinha
Keyword(s):  
Supersonic Jet ◽  
Turbine Engines ◽  
Far Field ◽  
Noise Levels ◽  
Physical Acoustics ◽  
Aircraft Carrier ◽  
Eddy Simulation ◽  
Field Investigations ◽  
Large Eddy ◽  
Field Noise

The hot supersonic exhausts of gas turbine engines on military aircraft generate dangerously high noise levels. The noise levels associated with operating these engines are harmful to aircraft carrier deck personnel as well as detrimental to ship and aircraft structures. In this paper, the supersonic jet exhaust is simulated using Large Eddy Simulation (LES), and the Ffowcs Williams and Hawkings (FW-H) equation transforms the LES solution to an acoustic solution in the far-field. A Mach 1.5 laboratory jet test at United Technologies Research Center - Acoustics Research Tunnel is used as validation for the LES/FW-H method. A grid refinement study was performed with the objective of determining the requirements for accurate noise predictions. The finest grid resolution yields the best near and far-field acoustic prediction. A second LES/FW-H validation case is shown for a twin jet experiment that was performed in the anechoic chamber at University of Mississippi’s National Center for Physical Acoustics (NCPA). The LES/FW-H method is applied to the higher complexity heated twin jet with faceted nozzle profiles, demonstrating the applicability of the method over a wider range of flow regimes. The far-field noise prediction agrees very well with the NCPA experiment, including the prediction of broadband shock associated noise and jet screech.

Large Eddy Simulations of Supersonic Impinging Jets

2012 ◽  
Author(s):  
James P. Erwin ◽  
Neeraj Sinha ◽  
Gregory P. Rodebaugh
Keyword(s):  
Impinging Jet ◽  
Impinging Jets ◽  
Far Field ◽  
Nozzle Throat ◽  
Aircraft Carrier ◽  
Eddy Simulation ◽  
Instability Modes ◽  
Large Eddy ◽  
Field Noise ◽  
Short Takeoff And Landing

Supersonic impinging jet flowfields contain self-sustaining acoustic feedback features that create high levels of discrete frequency tonal noise. These types of flowfields are typically found with short takeoff and landing military aircraft as well as jet blast deflector operations on aircraft carrier decks. The US Navy has a goal to reduce the noise generated by these impinging jet configurations and is investing in computational aeroacoustics to aid in the development of noise reduction concepts. In this paper, implicit Large Eddy Simulation (LES) of impinging jet flow-fields are coupled with a far-field acoustic transformation using the Ffowcs Williams and Hawkings (FW-H) equation method. The LES solves the noise generating regions of the flow in the nearfield, and the FW-H transformation is used to predict the far-field noise. The noise prediction methodology is applied to a Mach 1.5 vertically impinging jet at a stand-off distance of five nozzle throat diameters. Both the LES and FW-H acoustic predictions compare favorably with experimental measurements. Time averaged and instantaneous flowfields are shown. A calculation performed previously at a stand-off distance of four nozzle throat diameters is revisited with adjustments to the methodology including a new grid, time integrator, and longer simulation runtime. The calculation exhibited various feedback loops which were not present before and can be attributed to an explicit time marching scheme. In addition, an instability analysis of two heated jets is performed. Tonal frequencies and instability modes are identified for the sample problems.

Far-field noise prediction for jets using large-eddy simulation and Ffowcs Williams–Hawkings method

2016 ◽  
Vol 15 (8) ◽  
pp. 757-780 ◽  
Author(s):  
Iftekhar Z Naqavi ◽  
Zhong-Nan Wang ◽  
Paul G Tucker ◽  
M Mahak ◽  
Paul Strange
Keyword(s):  
Large Eddy Simulation ◽  
Noise Prediction ◽  
Far Field ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Field Noise

Far Field Noise Prediction for Subsonic Hot and Cold Jets Using Large-Eddy Simulation

2014 ◽  
Author(s):  
Zhong-Nan Wang ◽  
Iftekhar Z. Naqavi ◽  
Mahak Mahak ◽  
Paul Tucker ◽  
Xin Yuan ◽  
...  
Keyword(s):  
Large Eddy Simulations ◽  
Noise Prediction ◽  
Far Field ◽  
Temperature Ratio ◽  
Mean Velocity ◽  
Eddy Simulation ◽  
Large Eddy ◽  
The Mean ◽  
Simulation Results ◽  
Field Noise

Large eddy simulations are performed for hot and cold single stream jets with an acoustic Mach number of (Ma = Vj/a∞ = 0.875). The temperature ratio (Tj/T∞) for the hot jet is 2.7 and for the cold jet it is 1.0. Grids with 34 million points are used. The simulation results for the flow field are in encouraging agreement with the mean velocity and Reynolds stress measurements. The Ffowcs Williams-Hawkings (FW-H) equation is used to predict the far-field noise. In this study four cylindrical FW-H surfaces around the jet at various radial distances from the centreline are used. The FW-H surfaces are closed at the downstream end with multiple endplates. These endplates are at x = 25.0D – 30.0D with Δ = 0.5D apart. It is shown that surfaces close to jet get affected with pseudo sound. To avoid pseudo sound, surfaces must be placed in the irrotational region. To account for all the acoustic signals end plates are necessary. However, a simple averaging process to cancel pseudo sound at the end plates is not sufficient.

Wake-Airfoil Interaction as Broadband Noise Source: A Large-Eddy Simulation Study

2005 ◽  
Vol 4 (1-2) ◽  
pp. 93-115 ◽  
Author(s):  
Jérôme Boudet ◽  
Nathalie Grosjean ◽  
Marc C. Jacob
Keyword(s):  
Large Eddy Simulation ◽  
Particle Image ◽  
Broadband Noise ◽  
Far Field ◽  
Acoustic Analogy ◽  
Eddy Simulation ◽  
Naca0012 Airfoil ◽  
Image Velocimetry ◽  
Large Eddy ◽  
Proper Orthogonal

A large-eddy simulation is carried out on a rod-airfoil configuration and compared to an accompanying experiment as well as to a RANS computation. A NACA0012 airfoil (chord c = 0.1 m) is located one chord downstream of a circular rod (diameter d = c/10, Red = 48 000). The computed interaction of the resulting sub-critical vortex street with the airfoil is assessed using averaged quantities, aerodynamic spectra and proper orthogonal decomposition (POD) of the instantaneous flow fields. Snapshots of the flow field are compared to particle image velocimetry (PIV) data. The acoustic far field is predicted using the Ffowcs Williams & Hawkings acoustic analogy, and compared to the experimental far field spectra. The large-eddy simulation is shown to accurately represent the deterministic pattern of the vortex shedding that is described by POD modes 1 & 2 and the resulting tonal noise also compares favourably to measurements. Furthermore higher order POD modes that are found in the PIV data are well predicted by the computation. The broadband content of the aerodynamic and the acoustic fields is consequently well predicted over a large range of frequencies ([0 kHz; 10 kHz]).

Crackle Noise in Heated Supersonic Jets

2013 ◽  
Vol 135 (5) ◽  
Author(s):  
Joseph W. Nichols ◽  
Sanjiva K. Lele ◽  
Frank E. Ham ◽  
Steve Martens ◽  
John T. Spyropoulos
Keyword(s):  
Large Scale ◽  
Supersonic Jet ◽  
Supersonic Jets ◽  
Scale Model ◽  
Positive Pressure ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Total Temperature ◽  
Large Scale Flow ◽  
Large Eddies

Crackle noise from heated supersonic jets is characterized by the presence of strong positive pressure impulses resulting in a strongly skewed far-field pressure signal. These strong positive pressure impulses are associated with N-shaped waveforms involving a shocklike compression and, thus, is very annoying to observers when it occurs. Unlike broadband shock-associated noise which dominates at upstream angles, crackle reaches a maximum at downstream angles associated with the peak jet noise directivity. Recent experiments (Martens et al., 2011, “The Effect of Chevrons on Crackle—Engine and Scale Model Results,” Proceedings of the ASME Turbo Expo, Paper No. GT2011-46417) have shown that the addition of chevrons to the nozzle lip can significantly reduce crackle, especially in full-scale high-power tests. Because of these observations, it was conjectured that crackle is associated with coherent large scale flow structures produced by the baseline nozzle and that the formation of these structures are interrupted by the presence of the chevrons, which leads to noise reduction. In particular, shocklets attached to large eddies are postulated as a possible aerodynamic mechanism for the formation of crackle. In this paper, we test this hypothesis through a high-fidelity large-eddy simulation (LES) of a hot supersonic jet of Mach number 1.56 and a total temperature ratio of 3.65. We use the LES solver CHARLES developed by Cascade Technologies, Inc., to capture the turbulent jet plume on fully-unstructured meshes.

Numerical Investigation of 3-D Supersonic Jet Flows Using Large-Eddy Simulation

2012 ◽  
Vol 11 (7-8) ◽  
pp. 783-812 ◽  
Author(s):  
S.-C. Lo ◽  
K. M. Aikens ◽  
G. A. Blaisdell ◽  
A. S. Lyrintzis
Keyword(s):  
Large Eddy Simulation ◽  
Numerical Investigation ◽  
Supersonic Jet ◽  
Jet Flows ◽  
Eddy Simulation ◽  
Large Eddy

Flight Effects on the Far-Field Noise of a Heated Supersonic Jet

AIAA Journal ◽  
10.2514/2.203 ◽  
1997 ◽  
Vol 35 (6) ◽  
pp. 952-957 ◽  
Author(s):  
A. Krothapalli ◽  
P. T. Soderman ◽  
C. S. Allen ◽  
J. A. Hayes ◽  
S. M. Jaeger
Keyword(s):  
Supersonic Jet ◽  
Far Field ◽  
Field Noise
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