Effects of vorticity on rocket combustion stability

Flandro, Gary A.

doi:10.2514/3.23887

Cited by 172 publications

(138 citation statements)

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“…The coupling between the acoustic wave and the incoming radial mass flow from the propellant surface generates fluctuating vorticity and causes the energy transfer from the acoustic to the vortical field (flow-turning energy losses) [3,4]. The interactions between entropy fluctuations and non-uniform flow act as a strong source term for driving acoustic oscillations in regions with large velocity gradients [3,11]. The three waves, along with the transient combustion response of propellant, dictate the stability behavior of SRMs.…”

Section: Introductionmentioning

confidence: 99%

“…SRMs are subject to pressure oscillations caused by vortex shedding and acoustic feedback resulting from impingement of the vortices on the nozzle and other obstacles [3][4][5][6][7][8][9]. The oscillatory flowfield in a SRM consists of three distinct types of wave motions: acoustic (irrotational and compressible), vortical (rotational and incompressible) and entropy (arising from unsteady heat release) modes [10].…”

Section: Introductionmentioning

confidence: 99%

“…The oscillatory flowfield in a SRM consists of three distinct types of wave motions: acoustic (irrotational and compressible), vortical (rotational and incompressible) and entropy (arising from unsteady heat release) modes [10]. The coupling between the acoustic wave and the incoming radial mass flow from the propellant surface generates fluctuating vorticity and causes the energy transfer from the acoustic to the vortical field (flow-turning energy losses) [3,4]. The interactions between entropy fluctuations and non-uniform flow act as a strong source term for driving acoustic oscillations in regions with large velocity gradients [3,11].…”

Section: Introductionmentioning

confidence: 99%

“…Their effectiveness depends on oscillation frequencies, droplet sizes and burning-to-residence time ratio. Net contribution of aluminum to the global acoustic balance may be positive or negative [2,3,5].…”

Section: Introductionmentioning

confidence: 99%

“…In many cases, the stability of intra-chamber processes in SRMs is studied within the framework of the linear theory and acoustic balance methods ignoring interaction of acoustic and vortex motions [3,4]. 3 Two-phase flows with inert and burning aluminum particles as well as the influence of particles on acoustic oscillations in the combustion chamber are considered in [2,[12][13][14][15], where the results of numerical simulations based on the Eulerian-Eulerian and Eulerian-Lagrangean approaches and some experimental results are reported.…”

Section: Introductionmentioning

confidence: 99%

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Pressure oscillations and instability of working processes in the combustion chambers of solid rocket motors

et al. 2017

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Cite this article as: V.N. Emelyanov, I.V. Teterina, K.N. Volkov and A.U. Garkushev, Pressure oscillations and instability of working processesin the combustion chambers of solid rocket motors, Acta Astronautica, http://dx.doi.org/10. 1016/j.actaastro.2016.09.029 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. AbstractMetal particles are widely used in space engineering to increase specific impulse and to supress acoustic instability of intra-champber processes. A numerical analysis of the internal injection-driven turbulent gas-particle flows is performed to improve the current understanding and modeling capabilities of the complex flow characteristics in the combustion chambers of solid rocket motors (SRMs) in presence of forced pressure oscillations. The two-phase flow is simulated with a combined Eulerian-Lagrangian approach. The Reynolds-averaged Navier-Stokes equations and transport equations of -model are solved numerically for the gas. The particulate phase is simulated through a Lagrangian deterministic and stochastic tracking models to provide particle trajectories and particle concentration. The results obtained highlight the crucial significance of the particle dispersion in turbulent flowfield and high potential of statistical methods. Strong coupling between acoustic oscillations, vortical motion, turbulent fluctuations and particle dynamics is observed.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Pressure oscillations and instability of working processes in the combustion chambers of solid rocket motors

et al. 2017

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Solid Propulsion: Ignition Transients and Combustion Instability

Schlueter

Flandro

2010

Encyclopedia of Aerospace Engineering

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Ignition transients are a critical and complex period of operation in solid rocket motors. During the ignition interval, many factors combine that must be taken into account in the design of the entire system. There are many methods in use to analyze different aspects of the ignition processes, and the level of analysis complexity varies with need and available resources. These methods vary from empirically based sizing rules to complex physics‐based analyses. There are still many aspects of ignition transient behavior that have not been fully characterized, and research is continuing to fully understand all processes that occur during ignition transients in solid rocket motors. Combustion chamber pressure oscillations, often called combustion instability , can lead to dangerous vibration loads (“thrust roughness”) and elevation of motor operating pressure (“DC shift”). Frequencies are often associated with the chamber acoustic modes and cover a wide range from 10 Hz (in large solid rocket booster (SRB) motors) to over 30 kHz (in tactical rockets). Successful avoidance of these problems requires comprehensive understanding of a multitude of unsteady energy gain and loss mechanisms. The principal goals of current research are to predict (i) motor stability (tendency for oscillations to grow) and (ii) peak amplitude of the pressure oscillations throughout the motor burn. This information allows assessment of the threat to system operability and guides selection and application of corrective measures.

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Effect of Protrusion on Combustion Stability of Hybrid Rocket Motor

Dinesh

Kumar

2022

Propellants Explo Pyrotec

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In hybrid rockets, low regression rate and low combustion efficiency are major drawbacks restricting its utilization in practical applications. Inserting a protrusion in a hybrid rocket combustion chamber is one of the methods to enhance the regression rate and combustion efficiency. In the present study, while utilizing the protrusion method the combustion stability of the hybrid rocket was investigated. The protrusions used for this study were of two different types; one was made of graphite and another one was nylon. The nylon protrusion can regress during the combustion along with the fuel whereas, graphite cannot. Before using the protrusion method, the combustion stability of the hybrid rocket motor (base case) was characterized. During the combustion of the base case motor, intense pressure oscillations were observed for a definite period after the beginning of the combustion. These oscillations were found to be the result of the interaction between the vortex shedding and fundamental longitudinal acoustic modes of the chamber at the fuel grain exit. Upon inserting the protrusion near the fuel grain exit, significant suppression in the pressure oscillations was observed. A 96 % reduction in amplitude of acoustic modes relative to the base case was observed. There was no substantial difference in combustion stability of the hybrid rocket when using graphite or nylon protrusions. Further, it was realized that the combustion stability of the rocket motor remains unchanged even after varying the thickness of the protrusion at 0.8X/L location.

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Effects of vorticity on rocket combustion stability

Cited by 172 publications

References 7 publications

Pressure oscillations and instability of working processes in the combustion chambers of solid rocket motors

Pressure oscillations and instability of working processes in the combustion chambers of solid rocket motors

Solid Propulsion: Ignition Transients and Combustion Instability

Effect of Protrusion on Combustion Stability of Hybrid Rocket Motor

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