Eigenvalue Analysis for the Prediction of Initial Growth Rates of Thermoacoustic Instability in Rocket Motors

Schulze, Moritz; Sattelmayer, Thomas

doi:10.2514/6.2015-1606

Cited by 4 publications

(4 citation statements)

References 10 publications

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“…The mass flows are employed to determine chamber pressure in an iterative procedure 12,24 using the CEA software package developed by Gordon and McBride. 25,26 Results show that LP1 and LP2 operate at 70 bar, while 80 bar pressure is calculated for LP3 and LP4.…”

Section: Bkd Test Chamber and Lpsmentioning

confidence: 99%

“…As the application of the LEE allows to account for a representative mean nozzle flow, the nonreflectivity is directly account for. 10,24 To establish well-defined supersonic flow, a sufficient axial extent of the supersonic nozzle part is incorporated leading to a Mach number of approximately 1.4 at the computational outlet. As the outlet boundary at supersonic condition does not influence acoustic propagation inside the combustion chamber, its description is somewhat arbitrary.…”

mentioning

confidence: 99%

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Linear stability assessment of a cryogenic rocket engine

Schulze¹,

Sattelmayer²

2017

International Journal of Spray and Combustion Dynamics

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The linear high frequency stability of DLR's cryogenic H 2 /O 2 BKD test chamber is assessed using a hybrid computational fluid dynamic/computational aeroacoustic methodology, which is based on single flame simulations for the generation of an adequate mean flow and for the calibration of feedback models as well as on frequency space transformed linearized Euler equations. The application of a realistic mean flow field including combustion explains the spatial separation of transverse modes into a near face plate mode, which is found linearly unstable under certain operation conditions for the first transverse and a rear part mode. The axial mode shape length as well as eigenfrequencies is affected by propellant injection specifications and, in consequence, decisively influence pressure and transverse velocity sensitive dynamic flame response. The stability assessment procedure is finally applied to four operation conditions and the linear stability is predicted for the first transverse mode.

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Section: Bkd Test Chamber and Lpsmentioning

confidence: 99%

mentioning

confidence: 99%

Linear stability assessment of a cryogenic rocket engine

Schulze¹,

Sattelmayer²

2017

International Journal of Spray and Combustion Dynamics

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“…The combustor is typically acoustically resonant in nature. Thus predicting eigen-frequencies and mode-shapes and the growth rate of combustion-driven acoustic disturbances is needed [14]. Determining the modeshapes and eigen-frequencies [15] is not a difficult task by solving linearized Euler [16] or Helmholtz solvers in 1D network [17,18] or complex 2D [19] and 3D models [20].…”

Section: Introductionmentioning

confidence: 99%

Thermodynamics-Acoustics Coupling Studies on Self-Excited Combustion Oscillations Maximum Growth Rate

Zhao

2020

J. Therm. Sci.

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Unlike electric vehicles and electric aircrafts, hydrocarbon-fuelled (fossil) engine systems are much noisier. By conducting one-step chemical reaction-thermodynamics-acoustics coupling studies and experimental measurements, we explore the universal physics of how hydrocarbon-fuelled combustion is a noise maker. We also explain that how combustion-sustained noise at a particular frequency ω is intrinsically selected. These frequencies correspond to the acoustic resonance nature of the combustor. We find that a reacting gas in which the rate of chemical reacting increases with temperature is intrinsically and naturally unstable with respect to acoustic wave motion, since its modal growth rate α is greater than 0. Acoustic disturbances tend to exponentially i.e. exp(αt) increased first and then are limited by nonlinear effects and finally grow into limit cycle oscillations. The growth rate α is found to increase first and then decrease with the gradient of the heat release rate with respect to the temperature change, i.e. heat capacity. The maximum (α/ω) max depends on the specific heat ratio γ, which is related to the speed of sound. The unstable nature could be changed by introducing some acoustic dissipative/damping mechanism, such as the boundary layer viscous drag and boundary losses. It is shown that such losses could lead to increased critical heat capacity, below which stable combustors can be designed. Finally, the acoustical energy consisting of both potential and kinetic energy is found to grow exponentially faster by 100% than the acoustic disturbance amplitude.

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“…The linearized equations are then solved on the basis of the mean flow state. Such hybrid Computational Fluid Dynamic/Computational Aeroacoustic (CFD/CAA) approaches are very common in acoustic applications but also in the field of thermoacoustics, see [3,4]. On a very basic level the convective wave equation describes the acoustic propagation without considerations of spatial mean flow gradients.…”

Section: Introductionmentioning

confidence: 99%

Frequency domain simulations for the determination of liner effects on longitudinal wave propagation

Schulze

Sattelmayer

2015

International Journal of Aeroacoustics

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Frequency domain simulations are carried out in order to determine the effects of a liner on the propagation of longitudinal waves. On the basis of a CFD/CAA approach, three-dimensional linearized Euler equations (LEE) are transformed into frequency space and discretized using a stabilized Finite-Element technique to provide stable solution procedures and meaningful results. The code is validated on a Grazing Incidence Tube (GIT), which is operated at the NASA Langley Research Center. Results show that the frequency transformed LEE are very suitable to predict the acoustic propagation using experimentally determined liner impedances for different Mach numbers in the tube and further acoustic boundary conditions both at inlet and outlet of the test rig. In comparison to time-domain based approaches, computational times are reduced substantially and numerical instability issues are prevented. Furthermore, the relevance of detailed mean flow profiles and Myers impedance boundary conditions for the accurate prediction of the liner effect on the acoustic wave propagation is addressed. 1026 Frequency domain simulations for the determination of liner effects on longitudinal wave propagation aeroacoustics volume 14 • number 7 • 2015 1027 1028 Frequency domain simulations for the determination of liner effects on longitudinal wave propagation

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Eigenvalue Analysis for the Prediction of Initial Growth Rates of Thermoacoustic Instability in Rocket Motors

Cited by 4 publications

References 10 publications

Linear stability assessment of a cryogenic rocket engine

Linear stability assessment of a cryogenic rocket engine

Thermodynamics-Acoustics Coupling Studies on Self-Excited Combustion Oscillations Maximum Growth Rate

Frequency domain simulations for the determination of liner effects on longitudinal wave propagation

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