Thermo-acoustic Instability by Increased Hydrogen Content in Impinging Jet Flames of Syngas Fuel - Part I : Noise Radiation Characteristics by Self-excited Oscillation

Abstract The adaptation of high hydrogen content fuels for low emissions gas turbines represents a potential opportunity to reduce the carbon footprint of these devices. The high flame speed of hydrogen air mixtures combined with the small quenching distances poses a challenge for using these fuels in situations where significant premixing is desired. Flashback along the walls (i.e., boundary layer flashback) can be exacerbated with high hydrogen content fuels. In the present work, the ability of a flashback correlation previously developed for round jet flames is evaluated for its ability to predict flashback in an annular flow with and without swirl. Flashback data are obtained for various mixtures of hydrogen and methane and hydrogen and carbon monoxide for all the annular flow configurations. Pressures from 3-8 bar are tested with mixture temperatures up to 750 K. Flashback is induced by slowly increasing the equivalence ratio. The results obtained show that the same form of the correlation developed for round jet flames can be used to correlate flashback behavior for the annular flow case with and without swirl despite the presence of the centerbody. Adjustments to some of the constants in the original model were made to obtain the best fit, but in general, the correlation is quite similar to that developed for the round jet flame. A significant difference with the annular flow configurations is the determination of the appropriate gradient at the wall, which in the present case is determined using a cold flow CFD simulation.

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In‐Flight Far‐Field Measurement of Helicopter Impulsive Noise

Journal of the American Helicopter Society ◽

10.4050/jahs.21.4.2 ◽

1976 ◽

Vol 21 (4) ◽

pp. 2-16

Author(s):

F. H. Schmitz ◽

D. A. Boxwell

Keyword(s):

High Speed ◽

Impulsive Noise ◽

Operating Conditions ◽

Tape Recording ◽

Far Field ◽

Recording Equipment ◽

Radiation Characteristics ◽

Acoustic Data ◽

Noise Radiation ◽

The Subject

A new and highly successful method of collecting far‐field acoustic data radiated by helicopters in forward flight has been developed, utilizing a quiet aircraft flying in formation ahead of the subject helicopter. The lead aircraft, flown as an acoustic probe, was equipped with tape‐recording equipment and an external microphone. Spatial orientation of the helicopter with respect to the monitoring aircraft was achieved through visual flight reference. Far‐field acoustic data defining the impulsive noise radiation characteristics of the UH‐1H helicopter during high‐speed flight and partial ‐power descents have been gathered with this technique. Three distinct types of impulsive waveforms have been identified and correlated with helicopter steady operating conditions.

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Experimental Identification of Noise Radiation Characteristics and Noise Reduction in a Multi-Stage Centrifugal Air Compressor

Transactions of the Korean Society of Mechanical Engineers A ◽

10.3795/ksme-a.2020.44.4.301 ◽

2020 ◽

Vol 44 (4) ◽

pp. 301-312

Author(s):

Je-Heon Han ◽

Yaying Niu ◽

Changwoo Lim

Keyword(s):

Noise Reduction ◽

Radiation Characteristics ◽

Air Compressor ◽

Noise Radiation ◽

Experimental Identification ◽

Multi Stage

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Investigation on Impinging Jet Flames : Region and Mechanism of their stabilization

Bulletin of JSME ◽

10.1299/jsme1958.20.733 ◽

1977 ◽

Vol 20 (144) ◽

pp. 733-740

Author(s):

Atsushi SAIMA ◽

Morimasa HIGAKI

Keyword(s):

Impinging Jet ◽

Jet Flames

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Characterization of impinging jet flames

Combustion and Flame ◽

10.1016/s0010-2180(98)00084-4 ◽

1999 ◽

Vol 116 (4) ◽

pp. 671-674 ◽

Cited By ~ 39

Author(s):

Y ZHANG ◽

K BRAY

Keyword(s):

Impinging Jet ◽

Jet Flames

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The Nonlinearity during Start-Oscillation of Thermo-Acoustic Instability in Rijke-Type Combustor

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.204-210.1158 ◽

2011 ◽

Vol 204-210 ◽

pp. 1158-1161

Author(s):

Guo Neng Li ◽

Chen Yang Zang ◽

Kai Li

Keyword(s):

Acoustic Waves ◽

Nonlinear Effects ◽

Resonance Mode ◽

Limit Cycle Oscillation ◽

Main Resonance ◽

Acoustic Instability ◽

Short Period ◽

Excited Oscillation ◽

Cycle Oscillation ◽

Pressure Perturbations

In order to study the nonlinearity during the start-oscillation of thermo-acoustic instability, an experimental setup was built. The growing process of nonlinearity during the start-oscillation of thermo-acoustic instability was captured and analyzed. Experimental results revealed that after a suitable resonance mode corresponding to the structural of the combustor was selected, the pressure perturbations inside the combustor grow in amplitude into a very large amplitude and self-excited oscillation in a very short period of time. Then, slowly, the nonlinear effects adjust the shapes of pressure waveforms and amplify the oscillations. Ultimately, a limit-cycle oscillation with smooth and uniform pressure waveforms was obtained, and the acoustic waves exhibit only the main resonance mode, damping other modes of instability.

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