Broadband shock noise reduction in turbulent jets by water injection

Kandula, Max

doi:10.1016/j.apacoust.2008.12.001

Cited by 22 publications

(15 citation statements)

References 13 publications

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“…Absorption by water droplets is exploited 22 to reduce the sound reflected off the ground by the Space Shuttle when launched, 1 as this can damage instruments, although other effects (such as the entrainment of the liquid into the flow and its evaporation) are also important. [23][24][25] This is because the reduction of the sound source level of the jet (by decreasing jet transfer through momentum transfer between liquid and gaseous phases, and reduction in jet temperature through partial vaporization of the water) 26,27 are probably more important than the acoustic absorption that occurs during transmission. Literature features many poetical and fictional descriptions of how sound is changed in fog, although these perceptions also rely on more effects than are demonstrated here.…”

Section: Discussionmentioning

confidence: 98%

Demonstration comparing sound wave attenuation inside pipes containing bubbly water and water droplet fog

Leighton

Jiang

Baik

2012

The Journal of the Acoustical Society of America

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This paper describes a demonstration and explanation of sound absorption in water due to bubbles, and in air due to a fog of water droplets. It is suitable for 10-12 year olds, but the paper indicates where further exploration of the simplifications in the explanations provided for that age range would allow the demonstration to be used for undergraduate and Masters-level teaching. Applications to submarines, the space shuttle, and neutron generators are described. The demonstration is designed for transportation in a family-sized car.

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Section: Discussionmentioning

confidence: 98%

Demonstration comparing sound wave attenuation inside pipes containing bubbly water and water droplet fog

Leighton

Jiang

Baik

2012

The Journal of the Acoustical Society of America

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“…The fact that only a single shock-cell/vortex interaction is considered here indicates that the shock noise intensity obtained by the present formulation is essentially omnidirectional. It is believed that the present investigation would be helpful in our understanding of supersonic jet noise [51,52] and its suppression by active control such as water injection [53][54][55].…”

Section: Resultsmentioning

confidence: 99%

A Theoretical Basis for the Scaling Law of Broadband Shock Noise Intensity in Supersonic Jets

Kandula

2011

Advances in Acoustics and Vibration

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A theoretical basis for the scaling of broadband shock noise intensity in supersonic jets was formulated considering linear shockshear wave interaction. Modeling of broadband shock noise with the aid of shock-turbulence interaction with special reference to linear theories is briefly reviewed. A hypothesis has been postulated that the peak angle of incidence (closer to the critical angle) for the shear wave primarily governs the generation of sound in the interaction process with the noise generation contribution from off-peak incident angles being relatively unimportant. The proposed hypothesis satisfactorily explains the well-known scaling law for the broadband shock-associated noise in supersonic jets.

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“…It was pointed out by Kandula [25] that the effect of microjet injection in reducing jet noise was mainly by turbulence modification with no appreciable changes in the mean flowfield (velocity and temperature), and that water injection at relatively high MFR reduced jet noise by reducing the jet mean velocity and temperature. The prediction of turbulent jet mixing noise reduction with water injection [25] was recently extended to broadband shock noise [33]. Also, the spectral attenuation of sound with regard to turbulent jet mixing noise was investigated [34].…”

Section: Introductionmentioning

confidence: 99%

Suppression of High Mach Number Rocket Jet Noise by Water Injection

Sankaran¹,

Ignatius²,

Ramkumar³

et al. 2009

Journal of Spacecraft and Rockets

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The present work experimentally investigates suppression of the sound level from an underexpanded jet of Mach number 2.8 by water injection. The jet is produced by a solid rocket motor being static test fired. Water is injected from a radial distance of 5.2 jet diameters, at different axial locations from the exit of the nozzle, at two different angles of injection relative to the downstream jet axis. The ratio of mass flow rates of water to the nozzle exhaust gas (referred to as the mass flow rate ratio) and the injection pressure are varied independently. Acoustic measurements are performed at a radius of 30 jet diameters, over angles in the range of 30-130 deg, relative to the downstream jet axis. Sound levels continuously decrease by 10 dB with the increase in the angle of observation. With water injection, higher levels of reduction in sound are observed in the upstream quadrant. Injection closer to the nozzle exit leads to better reduction, mainly due to suppression in the high-frequency range when observed from downstream, but it is almost in the entire frequency range as observed at the upstream locations. At intermediate mass flow rate ratios, an optimum injection pressure exists for maximum noise suppression, due to the penetration of water to the potential core and its evaporation there at high injection pressures. The results affirm that the validity of many past studies obtained on water injection to suppress noise levels on simulated jets can be extended to an actual rocket situation.

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Broadband shock noise reduction in turbulent jets by water injection

Cited by 22 publications

References 13 publications

Demonstration comparing sound wave attenuation inside pipes containing bubbly water and water droplet fog

Demonstration comparing sound wave attenuation inside pipes containing bubbly water and water droplet fog

A Theoretical Basis for the Scaling Law of Broadband Shock Noise Intensity in Supersonic Jets

Suppression of High Mach Number Rocket Jet Noise by Water Injection

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