Experimental and Computational Investigation of Combustor Acoustics and Instabilities, Part I: Longitudinal Modes

Smith, Randolph; Nugent, Nicholas; Sisco, James C.; Xia, Guoping; Sankaran, Venkateswaran; Anderson, William E.; Merkle, Charles L.

doi:10.2514/6.2006-537

Cited by 6 publications

(4 citation statements)

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“…Even though the first longitudinal mode combustion instability took place, both signals at DP1 and DP2 moved in phase. This means that temperature was not axially uniform in the combustion chamber and thus temperature distribution affected the acoustic mode shape [15]. The filtered pressure fluctuation data in both manifolds also have large amplitude and are somewhat phase-delayed with those in the combustion chamber.…”

Section: Dynamic Combustion Characteristicsmentioning

confidence: 99%

“…Longitudinal mode combustion instabilities have been thoroughly studied [5,6,[13][14][15][16]. As the chamber length increased, the operation repeatedly alternated between unstable and stable in the longitudinal modes [13].…”

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confidence: 99%

“…As the chamber length increased, the operation repeatedly alternated between unstable and stable in the longitudinal modes [13]. Recently, combustion experiments in a single-element combustor with a gas-centered liquid swirl coaxial injector and their acoustic analysis were performed [14][15][16]. They suggested that the stability behavior was the result of the combined effects of chamber mode shape and driving combustion mechanism that limited the frequency range over which instability occurred.…”

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confidence: 99%

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Fuel-Rich Combustion Characteristics of Biswirl Coaxial Injectors

Ahn

Seo

Choi

2011

Journal of Propulsion and Power

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An experimental study was performed to investigate the combustion characteristics of liquid-liquid swirl coaxial injectors in fuel-rich conditions. Liquid oxygen and kerosene (Jet A-1) were burned in a range of mixture ratios (0.29-0.41) and chamber pressures (46-65 bar) in a gas generator for a liquid rocket engine. An injector head was connected to a water-cooled chamber and a short nozzle with or without an extension pipe between the chamber and the nozzle. The extension pipe acoustically simulated a turbine inlet manifold. The injector head had 37 identical swirl coaxial injectors. It is found that the characteristic velocity and combustion gas temperature are seldom influenced by the extension pipe, but are only functions of the mixture ratio. The dynamic pressure data show that the combustion instability in the fuel-rich gas generator equipped with biswirl coaxial injectors can be significantly affected by the mixture ratio and also by the extension pipe, which influences the resonant frequency in the chamber. Nomenclature C d = discharge coefficient c = speed of sound, m=s c = characteristic velocity, m=s d n = diameter of injector nozzle, mm d o;o = diameter of outer oxidizer post, mm d s = diameter of injector swirl chamber, mm d t = diameter of injector tangential hole, mm F peak = peak frequency, Hz l r = injector recess length, mm m = mass flow rate, kg=s n = number of injector tangential hole OFR = oxidizer-to-fuel mixture ratio p c = chamber pressure, bar p 0 c = pressure fluctuation in combustion chamber, bar p 0 fm = pressure fluctuation in fuel manifold, bar p 0 om = pressure fluctuation in oxidizer manifold, bar T avg = average temperature of combustion gas, K p inj = pressure differential through injector, bar Subscripts f = fuel o = oxidizer rms = root mean square

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Section: Dynamic Combustion Characteristicsmentioning

confidence: 99%

mentioning

confidence: 99%

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confidence: 99%

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Fuel-Rich Combustion Characteristics of Biswirl Coaxial Injectors

Ahn

Seo

Choi

2011

Journal of Propulsion and Power

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“…Over the past 2 decades, many investigations have been conducted, both experimentally (Kim et al, 2008;Ruan et al, 2020;Liu et al, 2021a) and theoretically (Culick, 1970;Coates and Horton, 1974;Bhatia and Sirignano, 1991;Sattelmayer, 2003). Typically, the longitudinal combustion instability has mostly been examined systematically at Purdue University (Smith et al, 2006(Smith et al, , 2010bYu, 2009;Wierman et al, 2012). Various scaled combustors with a single injector have been applied to study the longitudinal combustion instability mechanisms, including the Discretely Variable Resonance Combustor (DVRC (Frezzotti et al, 2014)), Continuously Variable Resonance Combustor (CVRC (Yu et al, 2008)), and Full-Flow Staged Combustor (Lemcherfi et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Three-Dimensional Numerical Analysis of Longitudinal Thermoacoustic Instability in a Single-Element Rocket Combustor

Guo

Ren

et al. 2022

Front. Energy Res.

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This study numerically investigated the thermoacoustic combustion instability characteristics of a scaled rocket combustor based on a hybrid of the Reynolds-averaged Navier–Stokes and large–eddy simulation method. The turbulence–combustion interactions were treated using flamelet generated manifold approach. An unstable case was simulated with detailed reaction mechanisms (GRI-Mech 3.0). The obtained results agree well with experiment data from Purdue University, in terms of pressure oscillations frequency and power spectral density spectrum. The combustion instability mode was identified to be coupled with the first longitudinal acoustic mode of the combustion chamber by dynamic model decomposition method. According to Rayleigh index analysis, the unstable driving source was found to be located near the combustor step, which was further confirmed by time-averaged flow fields. Detailed three-dimensional vortex ring shedding evolutions at the combustor step were tracked with fine time resolution. Results indicate that the combustion instability arises from periodic vortex ring shedding at the combustor step and interacting with the chamber wall. The unburnt reactants were rolled up by the shedding vortex ring, which would not break up until impact with the chamber wall. Therefore, the mixing performance was significantly enhanced, leading to sudden heat release. Consequently, the thermal energy is added to the acoustic field, and the first longitudinal mode is thus reinforced, giving rise to large amplitude axial velocity oscillations which prompt the generation of the new vortex ring. The results of the present investigation will support the design and development of high-performance rocket engines.

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