Skewness and shock formation in laboratory-scale supersonic jet data

Gee, Kent L.; Neilsen, Tracianne B.; Atchley, Anthony A.

doi:10.1121/1.4807307

Cited by 26 publications

(29 citation statements)

References 25 publications

(35 reference statements)

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“…Additionally, the skewness of the pressure derivative has a strong lobe with a maximum that aligns with the peak noise direction, and rapidly decreases at higher angles. Both of these results agree with observations from laboratory measurements by Gee et al [29], Krothapalli et al [30], and Barrs and Tinney [31], in addition to agreeing with the trends observed from full scale measurements [32]. The previously documented significant reductions in OASPL are observed in Fig.…”

Section: Heat Simulated Jetssupporting

confidence: 91%

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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Section: Heat Simulated Jetssupporting

confidence: 91%

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

Powers

Kuo

McLaughlin

et al. 2014

20th AIAA/CEAS Aeroacoustics Conference

View full text Add to dashboard Cite

show abstract

“…Additionally, the skewness of the pressure derivative has a strong lobe with a maximum that aligns with the peak noise direction, and rapidly decreases at higher angles. Both of these results agree with observations from laboratory measurements by Gee et al 18 , Krothapalli et al 19 , and Barrs and Tinney 20 , in addition to agreeing with the trends observed from full scale measurements 21 . The previously documented significant reductions in OASPL are observed in Figure 7, but now it can be observed that the polar angle of maximum emission is not altered by the fluidic inserts.…”

Section: B Experimental Approachsupporting

confidence: 91%

Prediction, Experiments and Optimization of High-Speed Jet Noise Reduction Using Fluidic Inserts

Morris¹,

McLaughlin

Powers

et al. 2014

50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference

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This paper describes several components of a study examining noise reduction in high speed heated jets using fluidic inserts. This noise reduction technology is based on the ideas developed by Seiner and his colleagues at NASA Langley Research Center and the University of Mississippi 1 . That approach was based on the introduction of corrugated seals into the diverging section of a convergent divergent nozzle. These corrugations change the effective area ratio so that the jet operates closer to an on-design condition and reduces broadband shock-associated noise. In addition, the corrugations generate streamwise vorticity that breaks up the large scale structures in the jet and reduces mixing noise. The idea behind fluidic inserts, described by Morris et al. 2 is to generate an equivalent effect with low levels of flow injection in the diverging section of the nozzle. This has the considerable advantage that the fluidic inserts can be controlled actively for maximum noise reduction and performance benefits. The present paper describes recent developments in the optimization of the fluidic insert concept. Flow and noise experiments, including the effect of forward flight are described. Numerical simulations are performed to characterize the flow features generated by the fluidic inserts as well as to develop measures of flow characteristics that can be related to the observed noise changes. These measures can be used to develop a cost function in a design optimization procedure.

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“…Rudenko and Chirkin 17 and Webster and Blackstock 18 showed that the probability density function of the waveform remains stationary until shocks form, which suggests that useful measures might be based on the temporal rates of change of the pressure. The statistics (i.e., skewness and/or kurtosis) of the waveform time derivative have been used to characterize the nonlinearity for initial sinusoids, 19 noise in a plane-wave tube, 20 and jet 10,[21][22][23][24][25][26] and rocket 27,28 noise. Baars and Tinney 11 have recently investigated a shock detection algorithm in the context of supersonic jet noise propagation for such metrics as number of shocks per unit time.…”

Section: Introductionmentioning

confidence: 99%

Evolution of the average steepening factor for nonlinearly propagating waves

Muhlestein

Gee

Neilsen

et al. 2015

The Journal of the Acoustical Society of America

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Difficulties arise in attempting to discern the effects of nonlinearity in near-field jet-noise measurements due to the complicated source structure of high-velocity jets. This article describes a measure that may be used to help quantify the effects of nonlinearity on waveform propagation. This measure, called the average steepening factor (ASF), is the ratio of the average positive slope in a time waveform to the average negative slope. The ASF is the inverse of the wave steepening factor defined originally by Gallagher [AIAA Paper No. 82-0416 (1982)]. An analytical description of the ASF evolution is given for benchmark cases-initially sinusoidal plane waves propagating through lossless and thermoviscous media. The effects of finite sampling rates and measurement noise on ASF estimation from measured waveforms are discussed. The evolution of initially broadband Gaussian noise and signals propagating in media with realistic absorption are described using numerical and experimental methods. The ASF is found to be relatively sensitive to measurement noise but is a relatively robust measure for limited sampling rates. The ASF is found to increase more slowly for initially Gaussian noise signals than for initially sinusoidal signals of the same level, indicating the average distortion within noise waveforms occur more slowly.

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Skewness and shock formation in laboratory-scale supersonic jet data

Cited by 26 publications

References 25 publications

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

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

Prediction, Experiments and Optimization of High-Speed Jet Noise Reduction Using Fluidic Inserts

Evolution of the average steepening factor for nonlinearly propagating waves

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