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.

Crackle Noise in Heated Supersonic Jets

2012 ◽  
Author(s):  
Joseph W. Nichols ◽  
Sanjiva K. Lele ◽  
Frank E. Ham ◽  
Steve Martens ◽  
John T. Spyropoulos
Keyword(s):  
Large Scale ◽  
Supersonic Jet ◽  
Jet Noise ◽  
Supersonic Jets ◽  
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 shock-like 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 [1] 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 high-fidelity Large-Eddy Simulation (LES) of a hot supersonic jet of Mach number 1.56 and total temperature 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.

Validation of a High-Order Large Eddy Simulation Solver for Acoustic Prediction of Supersonic Jet Flow

2020 ◽  
Vol 28 (03) ◽  
pp. 1950023
Author(s):  
Weiqi Shen ◽  
Steven A. E. Miller
Keyword(s):  
Large Eddy Simulation ◽  
Large Scale ◽  
Acoustic Radiation ◽  
Supersonic Jet ◽  
High Order ◽  
High Order Accuracy ◽  
Order Of Accuracy ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Mixing Noise

A high-order large eddy simulation (LES) code based on the flux reconstruction (FR) scheme is further developed for supersonic jet simulation. The FR scheme provides an efficient and easy-to-implement way to achieve high-order accuracy on an unstructured mesh. The order of accuracy and the shock capturing capability of the solver are validated with the isentropic Euler vortex and Sod’s shock tube problem. A heated under-expanded supersonic jet case from NASA’s Small Hot Jet Acoustic Rig (SHJAR) database is used for validation. The turbulence statistics along the nozzle centerline and lip-line are examined. We predict the acoustic radiation with the Ffowcs Williams and Hawkings method, which is integrated with our solver. The far-field acoustic predictions show reasonable agreement with the experimental measurement in the upstream and downstream directions, where the shock-associated noise and the large-scale turbulent mixing noise are dominant, respectively.

scholarly journals A Year-Long Large-Eddy Simulation of the Weather over Cabauw: An Overview

2015 ◽  
Vol 143 (3) ◽  
pp. 828-844 ◽  
Author(s):  
Jerôme Schalkwijk ◽  
Harmen J. J. Jonker ◽  
A. Pier Siebesma ◽  
Fred C. Bosveld
Keyword(s):  
Time Series ◽  
Large Eddy Simulation ◽  
Time Scales ◽  
Large Scale ◽  
Measurement Techniques ◽  
Three Dimensional ◽  
Scale Model ◽  
Eddy Simulation ◽  
Wide Range ◽  
Large Eddy

Abstract Results are presented of two large-eddy simulation (LES) runs of the entire year 2012 centered at the Cabauw observational supersite in the Netherlands. The LES is coupled to a regional weather model that provides the large-scale information. The simulations provide three-dimensional continuous time series of LES-generated turbulence and clouds, which can be compared in detail to the extensive observational dataset of Cabauw. The LES dataset is available from the authors on request. This type of LES setup has a number of advantages. First, it can provide a more statistical approach to the study of turbulent atmospheric flow than the more common case studies, since a diverse but representative set of conditions is covered, including numerous transitions. This has advantages in the design and evaluation of parameterizations. Second, the setup can provide valuable information on the quality of the LES model when applied to such a wide range of conditions. Last, it also provides the possibility to emulate observation techniques. This might help detect limitations and potential problems of a variety of measurement techniques. The LES runs are validated through a comparison with observations from the observational supersite and with results from the “parent” large-scale model. The long time series that are generated, in combination with information on the spatial structure, provide a novel opportunity to study time scales ranging from seconds to seasons. This facilitates a study of the power spectrum of horizontal and vertical wind speed variance to identify the dominant variance-containing time scales.

Two-point radiation statistics from large-scale turbulent structures within supersonic jets

2021 ◽  
pp. 1475472X2110054
Author(s):  
Jianhui Cheng ◽  
James D Goldschmidt ◽  
Weiqi Shen ◽  
Lawrence Ukeiley ◽  
Steven AE Miller
Keyword(s):  
Large Scale ◽  
Supersonic Jet ◽  
Jet Flows ◽  
Turbulent Structures ◽  
Instability Waves ◽  
Eddy Simulation ◽  
Instability Theory ◽  
Large Eddy ◽  
Noise Statistics ◽  
Heated Condition

The noise from large-scale coherent turbulent structures within jets remains the dominant source. For the purpose of developing future control systems for the large-scale noise source, we investigate the statistics between upstream and downstream radiating waves. We investigate two off-design supersonic jet flows with instability theory and associated noise radiation, large-eddy simulation (LES), and experiments. We compare the auto-correlation, cross-correlation, coherence, and other statistics predicted by aeroacoustic instability theory. As instability waves are closely connected with the formation of large-scale turbulent structures, they yield insight into large-scale noise statistics. We investigate two nozzles at two supersonic off-design conditions. The first is a biconic nozzle operating at an unheated condition, and the second is a NASA nozzle operating at a heated condition. We find that for these jets, the noise from instability waves is coherent between 0.40 to 0.70 at large-scale radiation frequencies between the downstream and upstream radiation directions.

scholarly journals LARGE-EDDY SIMULATION OF NOISE GENERATED BY PULSED SUPERSONIC JETS

Akustika ◽  
2019 ◽  
Vol 34 ◽  
pp. 136-140
Author(s):  
Pavel Chernyshov ◽  
Vladislav Emelyanov ◽  
Aleksey Tsvetkov ◽  
Konstantin Volkov
Keyword(s):  
Numerical Simulation ◽  
Large Eddy Simulation ◽  
Supersonic Jet ◽  
Supersonic Jets ◽  
Jet Flows ◽  
Noise Generation ◽  
Noise Sources ◽  
Jet Streams ◽  
Eddy Simulation ◽  
Large Eddy

Development of models and methods of modelling and simulation of the mechanisms of noise generation in jet streams plays an important role in various engineering applications due to strict requirements for noise produced by different industrial devices as well as the possibilities of using sound in technological processes. The computational tools of numerical simulation of gas dynamics and aeroacoustics processes in supersonic jet flows are considered, and noise sources and noise generation mechanisms in supersonic jets are discussed. The approach to numerical simulation is based on large-eddy simulation technique allowing to resolve eddy structures in the flowfield and to predict noise generation more accurately compared to the existing tools. The results obtained show the structure of under- and over-expanded supersonic jets and could be used to calculate sources of noise in supersonic flows.

scholarly journals Heat transfer in shallow caves: influence of turbulent convection

2021 ◽  
Vol 2116 (1) ◽  
pp. 012027
Author(s):  
B Qaddah ◽  
L Soucasse ◽  
F Doumenc ◽  
S Mergui ◽  
P Rivière ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Large Scale ◽  
Heat Diffusion ◽  
Scale Model ◽  
Conductive Heat ◽  
Turbulent Structures ◽  
External Temperature ◽  
Eddy Simulation ◽  
Cave Paintings ◽  
Large Scale Flow

Abstract The enhancement of the conservation conditions of cave paintings requires a detailed understanding of heat transfer in such cavities. This article presents a numerical investigation of turbulent free convection in a parallelepipedic cavity. Non-homogeneous wall temperatures are prescribed from a large-scale model taking into account external temperature fluctuations damped by heat diffusion in the rock massif above the cavity. Large Eddy Simulation is performed to solve the turbulent flow fields for a given wall temperature field corresponding to a Rayleigh number of 8.5 x 109. The outcomes of the model are analysed in terms of statistical mean. Results show complex large scale flow patterns with regions of high turbulent intensity. The Q-criterion is used to identify turbulent structures for an instantaneous flow field. Then we analyse the spatial distribution of the conductive heat flux at the walls to locate the regions with intense convection. We show that the conductive flux smaller than the wall-to-wall radiative flux in the major part of the cavity, and close to its value at some spots.

A Comparative Study of Flamelet and Finite Rate Chemistry LES for a Swirl Stabilized Flame

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
C. Fureby
Keyword(s):  
Large Scale ◽  
Small Scale ◽  
Reactor Model ◽  
Finite Rate ◽  
Eddy Simulation ◽  
Transient Nature ◽  
No Formation ◽  
Stirred Reactor ◽  
Large Eddy ◽  
Large Scale Flow

Present-day demands on combustion equipment are increasing the need for improved understanding and prediction of turbulent combustion. Large eddy simulation (LES), in which the large-scale flow is resolved on the grid, leaving only the small-scale flow to be modeled, provides a natural framework for combustion simulations as the transient nature of the flow is resolved. In most situations; however, the flame is thinner than the LES grid, and subgrid modeling is required to handle the turbulence-chemistry interaction. Here we examine the predictive capabilities between LES flamelet models, such as the flamelet progress variable (LES-FPV) model, and LES finite rate chemistry models, such as the thickened flame model (LES-TFM), the eddy dissipation concept (LES-EDC) model, and the partially stirred reactor model (LES-PaSR). The different models are here used to examine a swirl-stabilized premixed flame in a laboratory gas turbine combustor, featuring the triple annular research swirler (TARS), for which high-quality experimental data is available. The comparisons include velocity and temperature profiles as well as combustor dynamics and NO formation.

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