Supersonic jet noise from launch vehicles: 50 years since NASA SP-8072

Lubert, Caroline P.; Gee, Kent L.; Tsutsumi, Seiji

doi:10.1121/10.0009160

Cited by 25 publications

(17 citation statements)

References 242 publications

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“…Dhamanekar and Srinivasan's findings revealed that the central protrusion on the impinging plate exhibits greater efficacy in attenuating tones within supersonic impinging jets compared to those present in subsonic impinging jets. 38 Recently, Lubert et al 39 conducted a comprehensive review of the research conducted by NASA over the past 50 years on the physics underlying the generation and mitigation of noise from launch vehicles. Different noise reduction techniques for impinging jets can be found in the review articles of Jiang et al, 5 and Salehian and Mankbadi.…”

Section: Introduction and State Of The Artmentioning

confidence: 99%

Acoustic characteristics of jets impinging on permeable plates

Dhamanekar,

Srinivasan

2023

International Journal of Aeroacoustics

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This article explores the acoustic characteristics and the relevant flow features of jets impinging on permeable plates. Noise generated due to the interaction of the jet with permeable plates is compared with jets impinging on an impermeable plate and the corresponding free jet. This study systematically measures various parameters, including pore size, porosity, and pressure drop, to precisely quantify the permeability of the plates using the Forchheimer equation. The focus is on investigating the impact of permeability on noise reduction. An acoustic study is performed by carrying out blow-up and blow-down tests to find the effect of permeability at different nozzle pressure ratios and different nozzle-plate spacings. An extensive directivity study is conducted to find the directionality of acoustic emissions and calculate acoustic power. It is found that the overall sound pressure level is lower for the jets impinging on the permeable plates compared to the impermeable plates in subsonic cases. It is also observed that the insertion of the permeable plates in supersonic jets generates less noise compared to the corresponding free jet. It is found that most of the tones are absent in the case of permeable plates for supersonic jets, whereas the tones are present with lesser amplitude compared to jets impinging on impermeable plates for subsonic and transonic jets. Finally, flow measurement and flow visualization studies are carried out to understand the flow physics responsible for the noise variance. This study illuminates that the passage of flow through the porous plate results in the reduction of wall-jet velocities, thereby suppressing the turbulent mixing noise. The absence of shock oscillations in front of the permeable plate is identified as the cause of the mitigation of impinging tones.

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Section: Introduction and State Of The Artmentioning

confidence: 99%

Acoustic characteristics of jets impinging on permeable plates

Dhamanekar,

Srinivasan

2023

International Journal of Aeroacoustics

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“…There exist many limitations of the current understanding of the acoustic sources during a rocket launch (Lubert et al). 6 A phased array can be a very useful tool in filling these voids.…”

Section: Introductionmentioning

confidence: 99%

Acoustic sources identified using a microphone phased array during a rocket engine test

Panda,

Crowe,

Langford

et al. 2023

International Journal of Aeroacoustics

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A new phased array of microphones, suitable for the harsh environment of a rocket launch, was built and tested during a static firing of an RS-25 engine. It uses 70 piezo-resistive, dynamic pressure sensors, optimally distributed on a 10.5-ft diameter open frame dome structure and has a 200-ft long cable bundle to carry the signals to a weather-protected cabinet containing the data systems. The test stand was imaged using an infra-red camera and a visible wavelength camera, and the beamformed noise maps were superimposed on the photographs. The first-time data from a full-scale engine test stand showed that the plume deflector at the bottom of the engine was the primary noise source. The openings of the test stand around the nozzle exit were also found to be noise sources particularly at higher frequencies. The final goal is to utilize the array during NASA’s Artemis-II launch at Kennedy Space Center.

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“…These waves propagate to the launcher fairing, where they exert strong acoustic loads likely to damage the payload. The sound fields near the rocket structure thus require a specific attention from the aerospace industry, as highlighted in the review by Lubert et al [1]. In order to characterize them, the impingement of the gases exhausted by the engines on the launchpad can be modeled as a jet impinging on a flat plate.…”

Section: Introductionmentioning

confidence: 99%

Presence and properties of acoustic peaks near the nozzle of impinging rocket jets

Varé

Bogey

2022

Acta Acust.

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The presence and properties of acoustic peaks near the nozzle of impinging rocket jets have been investigated. Four jets at a Mach number of 3.1 impinging on a plate at a distance L = 15r0, 20r0, 25r0 and 30r0 from the nozzle, where r0 is the nozzle radius, have been computed using large-eddy simulations. In all cases, upstream-travelling pressure waves are generated by the jet impingement on the plate, with amplitudes decreasing with the nozzle-to-plate distance. The near-nozzle pressure spectra contain peaks, at frequencies not varying much with this distance. For L ≥ 20r0, the spectra are dominated by a low-frequency peak, whereas two additional high-frequency peaks emerge for L = 15r0. The low-frequency peak is associated with the azimuthal mode nθ = 0, whereas the two other ones are due to strong components for modes nθ ≥ 1. As for near-nozzle tones for free and impinging jets at lower Mach numbers, the peak frequencies fall close to the frequency bands of the upstream-propagating guided jet waves, showing a link between the peaks and the latter waves. Regarding the peak levels, they do not change significantly with the nozzle-to-plate distance for the low-frequency peak, but they decrease by 1.5 to 18 dB as the distance increases for the other peaks. Finally, for L ≥ 20r0, the near-nozzle peak frequency is close to that of the strongest shear-layer structures, indicating a connexion between the upstream noise and these structures. For L = 15r0, a shock-leakage mechanism of a near-plate shock is found to generate the upstream noise.

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Supersonic jet noise from launch vehicles: 50 years since NASA SP-8072

Cited by 25 publications

References 242 publications

Acoustic characteristics of jets impinging on permeable plates

Acoustic characteristics of jets impinging on permeable plates

Acoustic sources identified using a microphone phased array during a rocket engine test

Presence and properties of acoustic peaks near the nozzle of impinging rocket jets

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