Performance of a Gas Burning Rijke Pulse Combustor With Tangential Reactants Injection

Bai, T.; Cheng, Xiaoli; Daniel, B.R.; Jagoda, Jechiel I.; Zinn, B. T.

doi:10.1080/00102209308935300

Cited by 11 publications

(2 citation statements)

References 3 publications

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“…Thermo-acoustic systems have been exploited in the past to perform beneficial functions in a number of industrial applications. Examples include: promoting higher combustion efficiency, [10][11][12] fuel savings, 13,14 controlled waste incineration, 15 slurry atomization, 16 reduced pollutant formation, [17][18][19][20][21][22][23][24][25][26] increased fuel residence time in combustion chambers, [27][28][29] increased convective heat transfer rates, 30 and lower operating and equipment costs. 13,31,32 The basic mechanisms that trigger the beneficial consequences are invariably associated with controlling the acoustic field 31 in order to improve mixing 33 and/or heat transfer.…”

Section: Introductionmentioning

confidence: 99%

The Rijke tube revisited via laboratory and numerical experiments

Majdalani

2001

35th AIAA Thermophysics Conference

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In this paper, results proceeding from experimental studies and numerical simulations of the time-dependent flowfield inside a Rijke tube are presented and interpreted. A discussion is carried out based on existing speculations and standard scaling concepts. The main results include a similarity parameter that appears to play an important role in the heat driven oscillations. This parameter relates heat perturbations to velocity, pressure, and the square of a characteristic length. A hypothesis that relates heat oscillations to the compounded effects of pressure and velocity oscillations is discussed. This is done via computational, experimental, and scaling considerations. Since previous analytical theories have linked heat oscillations to either velocity or pressure coupling, the current analytical model agrees with and reconciles between both schools of thought. In compliance with the Rayleigh criterion, it is found that the heat source must be positioned at a critical distance of quarter length from the tube's entrance for resonance to occur. At that location, the modular product of acoustic velocity and pressure, known as the energy-flux vector modulus, is maximized. This observation confirms our proposed interpretation since the critical point where thermoacoustic coupling is maximized corresponds to the same spatial location where the modulus of acoustic intensity is largest. Furthermore, both numerical and laboratory experiments suggest that pressure oscillations inside the Rijke tube grow commensurately with increasing heat input. With a sufficiently small heat input, the acoustic sinks exceed the sources and acoustic attenuation takes place. In that case, no appreciable sound can be generated. Conversely, when the heat input is augmented beyond a critical threshold, acoustic sinks become insufficient, and rapid acoustic amplification ensues. The experiment also indicates the importance of the air's mean flow convection currents in the coupling mechanism. It is found that unless the air's mean flowrate is appreciable, no acoustic amplification can exist. To demonstrate the vitality of air currents, a strong mean flow is induced artificially by means of an exhaust fan. At the outset, acoustic growth is reported in both vertical and horizontal tube orientations. It is concluded that forced air currents can compensate for the lack of buoyancy in the horizontal tube configuration.

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Section: Introductionmentioning

confidence: 99%

The Rijke tube revisited via laboratory and numerical experiments

Majdalani

2001

35th AIAA Thermophysics Conference

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“…This phenomenon leads to excitation of acoustic eigenmodes. Thermoacoustic instability is utilized in thermoacoustic engines (Swift, 1988) and pulsed combustors (Bai et al, 1993), but it is undesirable in most industrial burners (Pun, 2001) and rocket motors (Culick, 1988), where thermal and acoustic pulsations degrade operational performance and increase emitted noise. The fundamental mechanisms of thermoacoustic instability can be studied using a Rijke tube, the simplest system exhibiting heat-driven acoustic oscillations.…”

Section: Introductionmentioning

confidence: 99%