Measurements of Jet Noise Aboard US Navy Aircraft Carriers

Aubert, Allan C.; McKinley, Richard L.

doi:10.2514/6.2011-6947

Cited by 19 publications

(7 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A related aspect is the exposure of carrier-deck personnel to extremely high sound pressure levels, which can cause hearing loss and other adverse health effects. 1 Solutions for tactical aircraft are bound to benefit future supersonic business jets that have similar operational characteristics.…”

Section: Introductionmentioning

confidence: 99%

Reduction of Radiation Efficiency in High-Speed Jets

Papamoschou

Xiong

Liu

2014

20th AIAA/CEAS Aeroacoustics Conference

View full text Add to dashboard Cite

The Lighthill acoustic analogy indicates that substantial noise reduction is possible in high-speed jets by reducing the radiation efficiency. This entails reducing the convective Mach number of the eddies whose footprint is sensed in the near pressure field. In dualstream jets, local reduction in convective Mach number is possible by inducing asymmetry in the plume that redistributes the most energetic eddies from the fast inner stream to the slower outer stream on the underside of the jet. Assuming that the convective velocity of the most energetic eddies is the mean velocity at the location of the peak turbulent kinetic energy, a RANS-based acoustic analogy predicts with reasonable fidelity the noise reduction measured experimentally. Importantly, it is shown that the reduction in the source strength is caused primarily by the reduction in radiation efficiency. A large eddy simulation of a single-stream high-subsonic jet allows determination of the convective velocity through space-time correlations throughout the computational domain. The convective velocity at the edge of the jet, defined as the boundary between the inner rotational field and the outer linear pressure field, is close to the mean axial velocity at the location of peak kinetic energy. This provides a tool for RANS-based acoustic analogy models to accurately predict the radiation efficiency and its reduction.

show abstract

Section: Introductionmentioning

confidence: 99%

Reduction of Radiation Efficiency in High-Speed Jets

Papamoschou

Xiong

Liu

2014

20th AIAA/CEAS Aeroacoustics Conference

View full text Add to dashboard Cite

show abstract

“…The skewness is defined as Sk p 03 , where p 0 is the pressure fluctuation and the overbar denotes time averaging. It is presented in the normalized form Sk∕σ 3 , where σ is the standard deviation. Figure 25 plots the directivity of the normalized skewness, in the downward azimuthal direction, associated with the following jets at cycle D: primary flow alone; coaxial flow; and eccentric flow from nozzle DEX2.…”

Section: Pressure Skewnessmentioning

confidence: 99%

“…Today, research on high-speed jet noise is primarily motivated by the need for tactical supersonic aircraft to become more environmentally acceptable. A related aspect is the exposure of carrier-deck personnel to extremely high sound pressure levels, which can cause hearing loss and other adverse health effects [3]. Solutions for tactical aircraft are bound to benefit future supersonic business jets that have similar operational characteristics.…”

mentioning

confidence: 99%

Aeroacoustics of Three-Stream High-Speed Jets from Coaxial and Asymmetric Nozzles

Papamoschou

Johnson

Phong

2014

Journal of Propulsion and Power

View full text Add to dashboard Cite

The development of three-stream variable-cycle turbofan engines for tactical aircraft provides an opportunity for noise reduction by shaping the exhaust of the secondary and tertiary streams. The paper reviews an experimental study of subscale three-stream jets operating at high specific thrust and issuing from rapid-prototyped nozzles. Exhaust conditions at four set points, with variable tertiary pressure ratio and bypass ratio, were determined using thermodynamic cycle analysis. Nozzles were fabricated for each set point and featured coaxial and non-coaxial exit geometries. The operating conditions were simulated using precisely metered helium-air mixtures, and far-field noise surveys were collected using a 24-microphone array. For a low-bypass ratio, a coaxial configuration offers no significant noise benefit compared to the single-stream primary jet. Configurations with offset secondary or tertiary streams offer significant noise reduction in the direction of the thicker flow. For an overall bypass ratio around 0.5, reductions of 5.1 dB in overall sound pressure level and 4.2 dB in effective perceived noise level were attained.

show abstract

“…As an example, we choose the highly intermittent acoustic Mach wave acoustic radiation of a hot turbulent jet. The jet-noise problem is of eminent technical interest for the aviation industry, in particular as it applies to naval aviation: aircraft carrier flight crew personnel operate in one of the world's loudest work environments, and regularly suffer from hearing loss due to overexposure to intermittent noise (Aubert & McKinley 2011). In figure 1, we contrast two time instances of the flow field obtained from a high-fidelity numerical simulation (Brès et al 2017).…”

Section: Introductionmentioning

confidence: 99%

A conditional space–time POD formalism for intermittent and rare events: example of acoustic bursts in turbulent jets

Schmidt

Schmid

2019

J. Fluid Mech.

View full text Add to dashboard Cite

We present a conditional space–time proper orthogonal decomposition (POD) formulation that is tailored to the eduction of the average, rare or intermittent events from an ensemble of realizations of a fluid process. By construction, the resulting spatio-temporal modes are coherent in space and over a predefined finite time horizon, and optimally capture the variance, or energy of the ensemble. For the example of intermittent acoustic radiation from a turbulent jet, we introduce a conditional expectation operator that focuses on the loudest events, as measured by a pressure probe in the far field and contained in the tail of the pressure signal’s probability distribution. Applied to high-fidelity simulation data, the method identifies a statistically significant ‘prototype’, or average acoustic burst event that is tracked over time. Most notably, the burst event can be traced back to its precursor, which opens up the possibility of prediction of an imminent burst. We furthermore investigate the mechanism underlying the prototypical burst event using linear stability theory and find that its structure and evolution are accurately predicted by optimal transient growth theory. The jet-noise problem demonstrates that the conditional space–time POD formulation applies even for systems with probability distributions that are not heavy-tailed, i.e. for systems in which events overlap and occur in rapid succession.

show abstract

Measurements of Jet Noise Aboard US Navy Aircraft Carriers

Cited by 19 publications

References 1 publication

Reduction of Radiation Efficiency in High-Speed Jets

Reduction of Radiation Efficiency in High-Speed Jets

Aeroacoustics of Three-Stream High-Speed Jets from Coaxial and Asymmetric Nozzles

A conditional space–time POD formalism for intermittent and rare events: example of acoustic bursts in turbulent jets

Contact Info

Product

Resources

About