Combustion Dynamics and Stability of a Fuel-Rich Gas Generator

Seo, Seonghyeon; Kim, Seong-Ku; Choi, Hwan-Seok

doi:10.2514/1.46568

Cited by 24 publications

(13 citation statements)

References 7 publications

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“…This reveals that the multielement combustor with internal mixing swirl coaxial injectors is vulnerable to low-frequency instability in the range of chamber pressure less than the critical pressure of oxygen. Although OFR was approximately 9 times smaller, this kind of low-frequency oscillation was also observed in the fuel-rich gas generator, which was equipped with internal mixing injectors and operated in chamber pressure below the critical pressure of oxygen (Seo et al, 2010b). Through all tests, low-frequency fluctuations exist in the vicinity of 140 Hz.…”

Section: Injector Recess and Chamber Pressure 261mentioning

confidence: 85%

“…A preset programmable logic controller (Allen Bradley) automatically controlled the opening and closing sequences of all the valves. The propellants injected into the chamber were ignited using a gaseous methane=oxygen torch flame (Seo et al, 2010b). Typical static pressure, propellant flow rate and raw dynamic pressure data in the case of HeadA_T3 are plotted in Figure 3.…”

Section: Combustion Testmentioning

confidence: 99%

“…Some researchers have observed low-frequency oscillations in liquid sheets and chamber pressure while using swirl injectors (Kim, 2007;Marchione et al, 2007;Seo et al, 2010a). In a fuel-rich gas generator composed of swirl coaxial injectors using LOx and kerosene, low-frequency pressure pulsations attenuated along with an increase of chamber pressure (Seo et al, 2010b). Though numerous cold flow tests and combustion tests were previously performed, a parametric study focusing on recess length and chamber pressure in a multielement combustor composed of LOx-kerosene swirl coaxial injectors is seldom reported in the open literature.…”

Section: Introductionmentioning

confidence: 96%

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Effects of Injector Recess and Chamber Pressure on Combustion Characteristics of Liquid–Liquid Swirl Coaxial Injectors

Ahn

Han

Seo

et al. 2010

Combustion Science and Technology

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Combustion characteristics such as combustion performance and combustion stability have been studied experimentally using a small liquid rocket thrust chamber with 19 liquid-liquid swirl coaxial injectors. Data were obtained from static pressure, temperature, and dynamic pressure sensors installed in propellant manifolds and the combustion chamber. While changing the recess length of the injector, characteristic velocity and pressure fluctuation data were collected and analyzed. In addition, chamber pressure was varied between 42 and 54 bar, which covers the sub-and supercritical pressures of oxygen. The results show that the longer recess length generally promotes combustion performance and the spray interaction between injectors in the multielement combustor increases the characteristic velocity. When the chamber pressure is above the critical pressure of oxygen, the recess length scarcely affects the pressure fluctuation. However, when the chamber pressure is below the critical pressure, the shift from external mixing to internal mixing of oxidizer and fuel sheets by the variation of recess length significantly degrades combustion stability and induces strong low-frequency instability. Accordingly, the effects of both recess length and operating chamber pressure must be taken into consideration when designing liquid-liquid swirl coaxial injectors.

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Section: Injector Recess and Chamber Pressure 261mentioning

confidence: 85%

Section: Combustion Testmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

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Effects of Injector Recess and Chamber Pressure on Combustion Characteristics of Liquid–Liquid Swirl Coaxial Injectors

Ahn

Han

Seo

et al. 2010

Combustion Science and Technology

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“…Relatively recent experimental investigation on combustion stability of non-equilirium combustion burning kerosene and liquid oxygen provided invaluable information. Seo et al 11 found that combustion with swirl coaxial injection has inherent pressure oscillations in the vincinty of 128 Hz, which may be generated from a coherent mixture pulsating associated with hydraulic characteristics of swirl flow. Combustion cases of the same injector with a long duct and chamber pressures less than the oxygen critical pressure were prone to a longitudinal high-frequency combustion instability.…”

Section: Introductionmentioning

confidence: 99%

Study on Combustion Dynamic Characteristics of Oxygen-Rich Preburners

Moon

Kang

Lee

et al. 2013

49th AIAA/ASME/SAE/ASEE Joint Propulsion Conference

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The present study experimentally investigates dynamic characteristics of combustion occurring at highly excessive oxygen environments. Combustion experiments bunring kerosene and liquid oxygen were conducted at chamber pressures of 5-20 MPa and their dynamic pressure fluctuations were measured. The systematic analysis of pressure data confirms that the combustion is sound with root-mean-square values below three percent of chamber pressures except a single condition of a chamber pressure of 8.9 MPa, at which low-frequency, bulk mode combustion instability at 78 Hz spontaneously occurred. The application of nonlinear time series analysis shows that certain hidden nonlinear behaviors can be identified implying that they may be utilized for the assessment of combustion stability margin. NomenclatureA o = exit cross sectional area of oxygen injector a = acoustic velocity d = time lag f H = Helmoholtz resonant frequency f = frequency resolution H = neighborhood of radius  I = average mutual information defind in Eq. (2) l o = internal axial length of oxygen injector m = embedding dimension N = total number of elements in time series data P = joint probability function p′ = pressure fluctuations p′ max = local maximum of pressure fluctuations p′ rms = root-mean-sqaure of pressuer fluctuations ⃗ = state vector t = time interval between adjacent data V c = combustion chamber internal volume  = radius in phase space  = phase difference  = Lyapunov exponent defined in Eq. (3)

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“…Previous researchers reported that they encountered combustion instability during development tests for gas generators [7][8][9][10][11][12]. Lawver [7] presented abundant data relating to characteristic velocity, gas temperature uniformity, and stability from fuel-rich/oxidizer-rich preburners with like-on-like impinging injectors and platelet injectors using liquid oxygen (LOX) and rocket propellant-1 (RP-1).…”

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confidence: 99%

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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Combustion Dynamics and Stability of a Fuel-Rich Gas Generator

Cited by 24 publications

References 7 publications

Effects of Injector Recess and Chamber Pressure on Combustion Characteristics of Liquid–Liquid Swirl Coaxial Injectors

Effects of Injector Recess and Chamber Pressure on Combustion Characteristics of Liquid–Liquid Swirl Coaxial Injectors

Study on Combustion Dynamic Characteristics of Oxygen-Rich Preburners

Fuel-Rich Combustion Characteristics of Biswirl Coaxial Injectors

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