Noise reduction in supersonic jets by nozzle fluidic inserts

Morris, Philip J.; McLaughlin, Dennis K.; Kuo, Ching Wen

doi:10.1016/j.jsv.2012.11.023

Cited by 70 publications

(46 citation statements)

References 8 publications

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“…Additionally, the relation between fully expanded jet Mach number and average shock spacing developed by Norum and Seiner 43 below in Eq. (5), was compared to the measured values:…”

Section: Resultsmentioning

confidence: 99%

“…Multiple technologies have been developed with the aim of producing streamwise vorticity to enhance jet mixing. For example, tabs, 2 fluidic injection, 5 notched nozzles, 6 and nozzle cross section 7 have all been used to this end. The primary challenge facing adoption of these technologies is achieving appreciable mixing enhancement without incurring large performance penalties.…”

Section: Introductionmentioning

confidence: 99%

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An experimental investigation of the flow dynamics of streamwise vortices of various strengths interacting with a supersonic jet

2014

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The results of an experimental study involving the introduction of streamwise vorticity into a supersonic jet are presented. Both streamwise and cross stream PIV measurements of a baseline jet and three vortex generator configurations of varied penetration were acquired in the overexpanded, ideally expanded, and underexpanded regimes. Streamwise vortex pairs were shown to persist no further than two diameters downstream independent of initial magnitude. Integration of the modulus of streamwise vorticity was shown to better correlate with secondary flow field modifications than maximum values. Reductions in shock cell spacing and downstream turbulence, and increases in initial spread rate and upstream integrated turbulence were correlated with increases in streamwise vorticity for all operating conditions. Streamwise vorticity was shown to achieve opposite effects on shock strength in the over/under expanded regimes due to introduction of secondary shock structures in the underexpanded case. Additionally, limited effect on potential core length was quantified.

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“…Additionally, the relation between fully expanded jet Mach number and average shock spacing developed by Norum and Seiner 43 below in Eq. (5), was compared to the measured values:…”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

An experimental investigation of the flow dynamics of streamwise vortices of various strengths interacting with a supersonic jet

2014

View full text Add to dashboard Cite

show abstract

“…Future experiments should be performed with direct comparison of equal momentum flux ratio such that the coarse measurement matrix and interpolated contours can be eliminated. In prior studies [7,8] on fluidic inserts, it was conjectured that cold jets could only be used to steer operating conditions for the heat-simulated jets, and the best results would not always occur at the same IPR orṁ ratio . This was hypothesized to be due to the lowered density of the helium-air jets.…”

Section: Heat Simulated Jetsmentioning

confidence: 99%

“…The research reported in this paper describes the results of enhancements made to an approach described in earlier publications [7,8], on nozzles with inserts replaced by fluidic corrugations. This is achieved by carefully distributed blowing in the divergent section of the nozzle.…”

Section: Introductionmentioning

confidence: 99%

Supersonic Jet Noise Reduction by Nozzle Fluidic Inserts with Simulated Forward Flight

Powers

Kuo

McLaughlin

et al. 2014

20th AIAA/CEAS Aeroacoustics Conference

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The noise produced by supersonic, high temperature jets that exhaust from military aircraft is becoming more of a disturbance. Methods to reduce the noise produced from these jets in a realistic full-scale environment is difficult. This study describes the development and analysis of fluidic inserts for supersonic jet noise suppression. Distributed blowing within the divergent section of the military-style convergent divergent nozzle alters the shock structure of the jet in addition to creating streamwise vorticity for the reduction of mixing noise. Enhancements to the fluidic insert design have been performed along with experiments for a large number of injection parameters and core jet conditions. It has been shown that the noise reduction of the fluidic inserts is most heavily dependent on the momentum flux ratio between the injector and core jet. Maximum reductions of approximately 5.5 dB OASPL have been observed with practical mass flow rates and injection pressures. The first measurements with fluidic inserts in the presence of a forward flight stream have been performed. Optimal noise reduction occurs at similar injector parameters in the presence of forward flight. Fluidic inserts in the presence of a forward flight stream were observed to reduce the peak mixing noise by nearly 4 dB OASPL and the broadband shock-associated noise by nearly 3 dB OASPL.

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“…Extensive investigations have been carried out by several researchers to understand such phenomena (Mitchell et al 2007;Leyko et al 2011;Morris et al 2013). Supersonic jets are routinely created in the laboratory by allowing high pressure gas to escape through a convergent-divergent (C-D) nozzle into a low pressure gas region.…”

Section: Introductionmentioning

confidence: 99%

Acetone planar laser-induced fluorescence for supersonic flow visualization in air and nitrogen jet

Shelar

Hegde

et al. 2014

Int J Mech Mater Eng

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Background: Laser based flow visualization techniques are indispensable tools for flow visualization in fluid dynamics and combustion diagnostics. Among these, PLIF is very popular because of its capability to give quantitative information about the flow. This paper reports the acetone tracer-based PLIF imaging of supersonic jet with air and nitrogen as bath gases. Methods: The tracer was seeded in the flow by purging bath gas through the liquid acetone at ambient temperature. Planar laser sheet from frequency quadrupled, Q-switched, Nd:YAG laser (266 nm) was used as an excitation source. Emitted PLIF images of a jet flow field were recorded on ICCD camera. Results: In this study, the dependence of PLIF images intensity on oxygen by comparing nitrogen jet with air in supersonic regime was presented. A lower temperature at the exit of the supersonic jet condenses the tracer which in turn forms droplets. Conclusions: There was a significant decrease in the PLIF image intensity in the case of air. This may be attributed to the oxygen present in the air. It is shown that image adding and Gaussian image processing of PLIF images for steadystate jet improve the quality of images.

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Noise reduction in supersonic jets by nozzle fluidic inserts

Cited by 70 publications

References 8 publications

An experimental investigation of the flow dynamics of streamwise vortices of various strengths interacting with a supersonic jet

An experimental investigation of the flow dynamics of streamwise vortices of various strengths interacting with a supersonic jet

Supersonic Jet Noise Reduction by Nozzle Fluidic Inserts with Simulated Forward Flight

Acetone planar laser-induced fluorescence for supersonic flow visualization in air and nitrogen jet

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