Nozzle Acoustic Dynamics and Stability Modeling

French, Jonathan; Flandro, Gary A.; Gloyer, Paul; Jacob, Eric J.

doi:10.2514/1.b34239

Cited by 13 publications

(4 citation statements)

References 5 publications

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“…The head end of the combustion chamber is a perfectly reflecting boundary. The nozzle end of the combustion chamber can also be assumed to be one (22,27) for computing eigen mode shapes and frequencies. This is valid for the lower modes whose characteristic wavelengths/length scales are much higher than the lateral dimension of the combustion chamber.…”

Section: Eigen-solvermentioning

confidence: 99%

“…Higher modes can couple with lateral modes and exchange energy depending on the nozzle shape. The frequencies and damping rates of higher axial modes may also be affected by the nozzle shape (27,28) .…”

Section: Eigen-solvermentioning

confidence: 99%

“…Admittance boundary conditions could also be applied at the nozzle end in a eigen-solver, but that would require separate computation of the complex nozzle admittance (29) , and errors associated with uncertainty about where this boundary condition is applied have been reported by French (27) . Eigen-solvers that include the nozzle portion also have been developed (27,28) , but their results for nozzle effects, especially decay rates, differ from direct admittance calculations using unsteady flow solvers (27,28) . For these reasons, the nozzle end is assumed to be a closed boundary in the eigen-analysis.…”

Section: Computational Toolsmentioning

confidence: 99%

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Damping of modal perturbations in solid rocket motors

et al. 2016

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Quasi-one-dimensional (quasi-1D) tools developed for capturing flow and acoustic dynamics in non-segmented solid rocket motors are evaluated using multi-dimensional computational fluid dynamic simulations and used to characterise damping of modal perturbations. For motors with high length-to-diameter ratios (of the order of 10), remarkably accurate estimates of frequencies and damping rates of lower modes can be obtained using the the quasi-1D approximation. Various grain configurations are considered to study the effect of internal geometry on damping rates. Analysis shows that lower cross-sectional area at the nozzle entry plane is found to increase damping rates of all the modes. The flow-turning loss for a mode increases if the more mass addition due to combustion is added at pressure nodes. For the fundamental mode, this loss is, therefore, maximum if burning area is maximum at the centre. The insights from this study in addition to recommendations made by Blomshield(1)based on combustion considerations would be very helpful in realizing rocket motors free from combustion instability.

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Section: Eigen-solvermentioning

confidence: 99%

Section: Eigen-solvermentioning

confidence: 99%

Section: Computational Toolsmentioning

confidence: 99%

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Damping of modal perturbations in solid rocket motors

et al. 2016

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“…Numerous works have highlighted the significance of nozzles concerning the flow analyses (see for instance [1,2,3]), the jet noise source and acoustics (see for instance [4,5,6,7,8]), the nozzle materials [9,10,11], the nozzle vibrations [12], the fluid-structure interactions and vibroacoustics [13,14,15,16], the nozzle optimization [17,18,19,20,21,22]. The effects of uncertainties in nozzle models have also been studied, see for instance [23,24,25,26].…”

Section: Introductionmentioning

confidence: 99%

Updating Nonlinear Stochastic Dynamics of an Uncertain Nozzle Model Using Probabilistic Learning With Partial Observability and Incomplete Dataset

Capiez-Lernout,

Ezvan,

Soize

2024

Journal of Computing and Information Science in Engineering

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This paper introduces a methodology for updating the nonlinear stochastic dynamics of a nozzle with uncertain computational model. The approach focuses on a high-dimensional nonlinear computational model constrained by a small target dataset. Challenges include the large number of degrees-of-freedom, geometric nonlinearities, material uncertainties, stochastic external loads, under-observability, and high computational costs. A detailed dynamic analysis of the nozzle is presented. An updated statistical surrogate model relating the observations of interest to the control parameters is constructed. Despite small training and target datasets, and partial observability, the study successfully applies Probabilistic Learning on Manifolds (PLoM) to address these challenges. PLoM captures geometric nonlinear effects and uncertainty propagation, improving conditional mean statistics compared to training data. The conditional confidence region demonstrates the ability of the methodology to accurately represent both observed and unobserved output variables, contributing to advancements in modeling complex systems.

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Effects of gas temperature on nozzle damping experiments on cold-flow rocket motors

Sun

et al. 2016

Acta Astronautica

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Nozzle Acoustic Dynamics and Stability Modeling

Cited by 13 publications

References 5 publications

Damping of modal perturbations in solid rocket motors

Damping of modal perturbations in solid rocket motors

Updating Nonlinear Stochastic Dynamics of an Uncertain Nozzle Model Using Probabilistic Learning With Partial Observability and Incomplete Dataset

Effects of gas temperature on nozzle damping experiments on cold-flow rocket motors

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