Numerical predictions of noise due to subsonic jets from nozzles with and without chevrons

Tide, P. S.; Babu, V.

doi:10.1016/j.apacoust.2008.03.006

Cited by 33 publications

(21 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Tide and Babu [13] have performed unsteady RANS (URANS) type calculations in combination with the Ffowcs Williams -Hawkings (FWH) method to simulate nozzles with and without chevrons. Although no noise spectra for the chevron nozzle jet are presented in their paper, they have shown that URANS could not predict the noise spectra for the baseline nozzle without chevrons.…”

Section: Introductionmentioning

confidence: 99%

High-Fidelity Numerical Simulation of a Chevron Nozzle Jet Flow

Uzun

Jiang

Hussaini

2011

International Journal of Aeroacoustics

View full text Add to dashboard Cite

We report results from the simulation of a moderate Reynolds number cold jet flow exhausting from a chevron nozzle with six symmetric chevrons that have an approximately 18-degree penetration angle. The flow inside the nozzle geometry and the free jet flow outside are computed simultaneously by a high-order accurate, multi-block, large eddy simulation code with overset grid capability. The simulation is performed on 400 million grid points using 2048 processor cores in parallel. The main emphasis of the simulation is to compute the jet flow in maximum detail possible and accurately capture the physical processes that lead to noise generation. It is especially critical to capture the enhanced shear layer mixing due to chevrons that takes place within the first few diameters downstream of the nozzle exit. Our calculations resolve the jet flow field at an unprecedented level of detail. Despite some issues such as an order of magnitude lower simulation Reynolds number (relative to experimental value) and unknown turbulence intensity levels within the experimental nozzle, it is shown that both the near-field jet turbulence and far-field noise predictions are in good agreement with the experimental measurements. Because of the enormous number of grid points required to resolve the near-nozzle region, the computational domain size is constrained to ten nozzle exit diameters downstream of nozzle exit by the limited computational resources. As a result, not all of the low frequency generating noise sources are resolved in the calculation, resulting in some errors in the low frequency range of the predicted noise spectrum. Nevertheless, it is shown that the high frequency noise generation in the near-nozzle region is

show abstract

Section: Introductionmentioning

confidence: 99%

High-Fidelity Numerical Simulation of a Chevron Nozzle Jet Flow

Uzun

Jiang

Hussaini

2011

International Journal of Aeroacoustics

View full text Add to dashboard Cite

show abstract

“…Although Andersson et al (2003) used LES for their numerical simulation of subsonic jets emanating from circular nozzle, the same trend showing sudden spike of Reynolds stresses was noticed. This again was validated by Tide and Babu (2009a, 2009b) after repeating the numerical simulations using Favre averaged Navier–Stokes equations coupled with SST k - ω model on an identical circular nozzle reported by Andersson et al (2003).…”

Section: Resultsmentioning

confidence: 74%

“…Usually, skewness measure values below 0.8 are acceptable. A similar domain and grid was used by Tide and Babu (2009a, 2009b) for their calculations of flow characteristics of jets emanating from chevron nozzles.…”

Section: Problem Description and Solution Methodologymentioning

confidence: 99%

“…This can both intensify and suppress the noise. Two jets, one cold and one hot, were simulated by Tide and Babu (2009a) from nozzles with and without chevrons. They compared plots of u ′ u ′ ¯, v ′ v ′ ¯ and u ′ v ′ ¯ along axial and radial direction of jet with the experimental values and found that unsteady reynolds averaged Navier Stokes (URANS) calculation can be used to predict the trends of flow reasonably well.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Numerical predictions of the flow characteristics of subsonic jet emanating from corrugated lobed nozzle

Paul

Kriparaj

Tide

2020

AEAT

View full text Add to dashboard Cite

Purpose The purpose of this study is to investigate the aerodynamic characteristics of subsonic jet emanating from corrugated lobed nozzle. Design/methodology/approach Numerical simulations of subsonic turbulent jets from corrugated lobed nozzles using shear stress transport k-ω turbulence model have been carried out. The analysis was carried out by varying parameters such as lobe length, lobe penetration and lobe count at a Mach number of 0.75. The numerical predictions of axial and radial variation of the mean axial velocity, u′u′ ¯ and v′v′ ¯ have been compared with experimental results of conventional round and chevron nozzles reported in the literature. Findings The centreline velocity at the exit of the corrugated lobed nozzle was found to be lower than the velocity at the outer edges of the nozzle. The predicted potential core length is lesser than the experimental results of the conventional round nozzle and hence the decay in centreline velocity is faster. The centreline velocity increases with the increase in lobe length and becomes more uniform at the exit. The potential core length increases with the increase in lobe count and decreases with the increase in lobe penetration. The turbulent kinetic energy region is narrower with early appearance of a stronger peak for higher lobe penetration. The centreline velocity degrades much faster in the corrugated nozzle than the chevron nozzle and the peak value of Reynolds stress appears in the vicinity of the nozzle exit. Practical implications The corrugated lobed nozzles are used for enhancing mixing without the thrust penalty inducing better acoustic benefits. Originality/value The prominent features of the corrugated lobed nozzle were obtained from the extensive study of variation of flow characteristics for different lobe parameters after making comparison with round and chevron nozzle, which paved the way to the utilization of these nozzles for various applications.

show abstract

“…Tide and Babu [13] have performed unsteady RANS (URANS) calculations in combination with the Ffowcs Williams-Hawkings (FWH) method to simulate nozzles with and without chevrons. Although no noise spectra for the chevron nozzle jet are presented in their paper, they have shown that URANS could not predict the noise spectra for the baseline nozzle without chevrons.…”

Section: Introductionmentioning

confidence: 99%

Some Issues in Large-Eddy Simulations for Chevron Nozzle Jet Flows

Uzun

Hussaini

2012

Journal of Propulsion and Power

View full text Add to dashboard Cite

Some important issues that were encountered during large-eddy simulations of chevron nozzle jet flows and their noise are discussed. These issues have quite an impact on the predictions of the numerical simulations. The issues are classified into four main topics: 1) generation of realistic nozzle inflow conditions, 2) optimal grid resolution of chevron jet shear layers, 3) limited axial domain size in well-resolved simulations due to limited computational resources, and 4) relatively low simulation Reynolds-number limitation in well-resolved simulations. Solutions to the first three issues are proposed and implemented. The last issue concerning well-resolved simulations at practical high Reynolds numbers is the most difficult one to resolve, as the Reynolds number directly dictates the number of grid points needed in a well-resolved simulation. An approach for fairly well-resolved simulations of high Reynolds number jet flows is outlined. Although this proposed approach still requires a significant number of grid points, it is believed that it should be feasible on the powerful supercomputers of the present day. The practical implementation of the proposed approach for high Reynolds number jet flows remains to be demonstrated through future work.

show abstract

Numerical predictions of noise due to subsonic jets from nozzles with and without chevrons

Cited by 33 publications

References 24 publications

High-Fidelity Numerical Simulation of a Chevron Nozzle Jet Flow

High-Fidelity Numerical Simulation of a Chevron Nozzle Jet Flow

Numerical predictions of the flow characteristics of subsonic jet emanating from corrugated lobed nozzle

Some Issues in Large-Eddy Simulations for Chevron Nozzle Jet Flows

Contact Info

Product

Resources

About