Understanding jet noise

Karabasov, Sergey A.

doi:10.1098/rsta.2010.0086

Cited by 42 publications

(16 citation statements)

References 36 publications

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“…For example, one of the early approaches based on Lilley's (1972) equation, which is still used in modern noise prediction codes (Khavaran, Bridges & Georgiadis 2005), explicitly accounts for sound interaction with a simplified jet mean flow. More discussion on acoustic analogy methods can be also found in Morris & Farassat (2002), Tam et al (2008), Michel (2009), Morris (2009), Karabasov (2010 and Goldstein (2011).…”

Section: Introductionmentioning

confidence: 99%

An investigation of the mechanisms of sound generation in initially laminar subsonic jets using the Goldstein acoustic analogy

2013

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The details of the sound sources within two initially laminar subsonic jets corresponding to different inflow conditions, one fully laminar and the other with nozzle boundary layer forcing, are studied using the Goldstein acoustic analogy. The statistics of the acoustic analogy equivalent sources are generated from large eddy simulations (LES) and issues associated with the range of validity of these are explored. The predicted comparative importance of various source terms confirms the results of previous studies, with the exception of one extra term that involves the longitudinal and the lateral source components. Agreement within 1 dB over the frequency range from Strouhal number $\mathit{St}= 0. 8$ to $\mathit{St}= 6$, which was shown to best correspond to the validity range of the acoustic source model for the LES data available, is found between noise predictions using the acoustic analogy model and those of a previously conducted LES–ILEE (isotropic linearized Euler equation) control surface method for the nominally laminar inflow jet case. The acoustic analogy is used to determine the source length scales which contribute to noise at different radiated angles to the jet, how they are distributed and how they change with change of inflow conditions. For the vortex pairing frequency, using a new acoustic source decomposition technique based on the correlation length scale, two types of noise sources are found. One source, which corresponds to the peak source amplitude, is located at the upstream end of the jet and is associated with the vortex pairing. The other one, which is the dominant source, is associated with jet mixing at the end of the jet potential core. It is also shown that boundary layer forcing leads to a reduction in the contribution to the noise of the large source length scales in comparison with the fully laminar case.

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Section: Introductionmentioning

confidence: 99%

An investigation of the mechanisms of sound generation in initially laminar subsonic jets using the Goldstein acoustic analogy

2013

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“…Because flow velocities are low for this application and similar in a fan or in a nozzle application, noise should be lower in the latter. This hypothesis can be demonstrated with experimental and analytical studies performed by Karabasov [22].…”

Section: Previous Workmentioning

confidence: 77%

Assessment of the Economic and Environmental Impact of Double Glazed Façade Ventilation Systems in Mediterranean Climates

Valentín

Guardo

Valero³

et al. 2013

Energies

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Free convection is the most often used method in order to reduce solar load gains on a building with double glazed façades (DGFs). However, depending on the climate factors, the thermal performance of a DGF may not be satisfactory and extra energy costs are required to obtain suitable comfort conditions inside the building. Forced ventilation systems are a feasible alternative to improve the thermal performance of a DGF in Mediterranean climates where large solar gains are a permanent condition throughout the year. In this paper the feasibility of using diverse forced ventilation methods in DGF is evaluated. In addition, an economical comparison between different mechanical ventilation systems was performed in order to demonstrate the viability of DGF forced ventilation. Moreover, an environmental study was carried out to prove the positive energetic balance on cooling loads between free and forced convection in DGF for Mediterranean climates. For this investigation, a CFD model was used to simulate the thermal conditions in a DGF for the different ventilation systems. Results obtained for heat flux, temperature and reductions in solar load gains were analyzed and applied for the economic and environmental research.

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“…They all share a general idea to exactly rearrange the governing NS equations into the form of non-homogeneous linear equations and a nonlinear source at the righthand side. For most advanced approaches of this type [35][36][37], the nonlinear source is directly related to the properties of fine-scale solution (space-time scales of the turbulence). In this work, the model based on a hydrodynamic analogy with two-phase flows is proposed for coupling the LL-FH and MD equations.…”

Section: Coupling Of the Landau-lifshitz Fluctuating Hydrodynamics Anmentioning

confidence: 99%

Concurrent multiscale modelling of atomistic and hydrodynamic processes in liquids

Markesteijn

Karabasov

Scukins

et al. 2014

Phil. Trans. R. Soc. A.

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One contribution of 13 to a Theme Issue 'Multi-scale systems in fluids and soft matter: approaches, numerics and applications' . Fluctuations of liquids at the scales where the hydrodynamic and atomistic descriptions overlap are considered. The importance of these fluctuations for atomistic motions is discussed and examples of their accurate modelling with a multi-spacetime-scale fluctuating hydrodynamics scheme are provided. To resolve microscopic details of liquid systems, including biomolecular solutions, together with macroscopic fluctuations in space-time, a novel hybrid atomistic-fluctuating hydrodynamics approach is introduced. For a smooth transition between the atomistic and continuum representations, an analogy with two-phase hydrodynamics is used that leads to a strict preservation of macroscopic mass and momentum conservation laws. Examples of numerical implementation of the new hybrid approach for the multiscale simulation of liquid argon in equilibrium conditions are provided.

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Understanding jet noise

Cited by 42 publications

References 36 publications

An investigation of the mechanisms of sound generation in initially laminar subsonic jets using the Goldstein acoustic analogy

An investigation of the mechanisms of sound generation in initially laminar subsonic jets using the Goldstein acoustic analogy

Assessment of the Economic and Environmental Impact of Double Glazed Façade Ventilation Systems in Mediterranean Climates

Concurrent multiscale modelling of atomistic and hydrodynamic processes in liquids

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