Effect of elastic case on stability of radial modes in solid propellant rockets

J. D. Achenbach; C. T. Sun

doi:10.2514/3.28837

Effect of elastic case on stability of radial modes in solid propellant rockets

J. D. Achenbach, C. T. Sun

Research output: Contribution to journal › Article › peer-review

2 Scopus citations

Abstract

The coupling of the combustion process and the mechanical vibrations of a solid propellant rocket may result in acoustic instability if a mechanical disturbance is amplified by energy release in the combustion zone. Acoustic stability depends on the balance of energy sources and energy sinks. Energy dissipations in the gas and the viscoelastic solid propellant binder are taken into account. The instantaneous frequencies of the structural system are determined from the undamped system. In this paper the influence of relative thickness of the elastic case on acoustic stability of the lowest radial mode is discussed. It is found that in the early part of the burning process a thicker case makes a more stable motor. Near burnout, however, the motor becomes more stable for a thinner case.

Original language	English (US)
Pages (from-to)	214-219
Number of pages	6
Journal	Journal of Spacecraft and Rockets
Volume	4
Issue number	2
DOIs	https://doi.org/10.2514/3.28837
State	Published - Mar 1967
Externally published	Yes

Funding

A SOLID propellant rocket motor can be regarded as a structural system consisting of a steel case that contains two media, solid propellant and gas, which are separated by a thin combustion zone. Since combustion of a solid propellant represents an intensive source of energy liberation, it is to be expected that part of the released energy will be transmitted to the structural system, thereby amplifying incipient oscillations in the gas-propellant-case system.1 Conversely, the induced pressure variations in the gas will cause fluctuations in combustion rate, thus providing a feedback from the Presented as Preprint 66-473 at the AIAA 4th Aerospace Sciences Meeting, Los Angeles, Calif., June 27-29, 1966; submitted July 26, 1966; revision received November 1, 1966. The work reported in this paper was supported by the Office of Naval Research underContractONR Nonr. 1228(34) withNorthwestern University. * Associate Professor, Department of Civil Engineering. Member AIAA. f Graduate Student, Department of Civil Engineering.

ASJC Scopus subject areas

Aerospace Engineering
Space and Planetary Science

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10.2514/3.28837

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title = "Effect of elastic case on stability of radial modes in solid propellant rockets",

abstract = "The coupling of the combustion process and the mechanical vibrations of a solid propellant rocket may result in acoustic instability if a mechanical disturbance is amplified by energy release in the combustion zone. Acoustic stability depends on the balance of energy sources and energy sinks. Energy dissipations in the gas and the viscoelastic solid propellant binder are taken into account. The instantaneous frequencies of the structural system are determined from the undamped system. In this paper the influence of relative thickness of the elastic case on acoustic stability of the lowest radial mode is discussed. It is found that in the early part of the burning process a thicker case makes a more stable motor. Near burnout, however, the motor becomes more stable for a thinner case.",

author = "Achenbach, {J. D.} and Sun, {C. T.}",

note = "Funding Information: A SOLID propellant rocket motor can be regarded as a structural system consisting of a steel case that contains two media, solid propellant and gas, which are separated by a thin combustion zone. Since combustion of a solid propellant represents an intensive source of energy liberation, it is to be expected that part of the released energy will be transmitted to the structural system, thereby amplifying incipient oscillations in the gas-propellant-case system.1 Conversely, the induced pressure variations in the gas will cause fluctuations in combustion rate, thus providing a feedback from the Presented as Preprint 66-473 at the AIAA 4th Aerospace Sciences Meeting, Los Angeles, Calif., June 27-29, 1966; submitted July 26, 1966; revision received November 1, 1966. The work reported in this paper was supported by the Office of Naval Research underContractONR Nonr. 1228(34) withNorthwestern University. * Associate Professor, Department of Civil Engineering. Member AIAA. f Graduate Student, Department of Civil Engineering.",

year = "1967",

month = mar,

doi = "10.2514/3.28837",

language = "English (US)",

volume = "4",

pages = "214--219",

journal = "Journal of Spacecraft and Rockets",

issn = "0022-4650",

publisher = "American Institute of Aeronautics and Astronautics Inc. (AIAA)",

number = "2",

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AU - Achenbach, J. D.

AU - Sun, C. T.

N1 - Funding Information: A SOLID propellant rocket motor can be regarded as a structural system consisting of a steel case that contains two media, solid propellant and gas, which are separated by a thin combustion zone. Since combustion of a solid propellant represents an intensive source of energy liberation, it is to be expected that part of the released energy will be transmitted to the structural system, thereby amplifying incipient oscillations in the gas-propellant-case system.1 Conversely, the induced pressure variations in the gas will cause fluctuations in combustion rate, thus providing a feedback from the Presented as Preprint 66-473 at the AIAA 4th Aerospace Sciences Meeting, Los Angeles, Calif., June 27-29, 1966; submitted July 26, 1966; revision received November 1, 1966. The work reported in this paper was supported by the Office of Naval Research underContractONR Nonr. 1228(34) withNorthwestern University. * Associate Professor, Department of Civil Engineering. Member AIAA. f Graduate Student, Department of Civil Engineering.

PY - 1967/3

Y1 - 1967/3

N2 - The coupling of the combustion process and the mechanical vibrations of a solid propellant rocket may result in acoustic instability if a mechanical disturbance is amplified by energy release in the combustion zone. Acoustic stability depends on the balance of energy sources and energy sinks. Energy dissipations in the gas and the viscoelastic solid propellant binder are taken into account. The instantaneous frequencies of the structural system are determined from the undamped system. In this paper the influence of relative thickness of the elastic case on acoustic stability of the lowest radial mode is discussed. It is found that in the early part of the burning process a thicker case makes a more stable motor. Near burnout, however, the motor becomes more stable for a thinner case.

AB - The coupling of the combustion process and the mechanical vibrations of a solid propellant rocket may result in acoustic instability if a mechanical disturbance is amplified by energy release in the combustion zone. Acoustic stability depends on the balance of energy sources and energy sinks. Energy dissipations in the gas and the viscoelastic solid propellant binder are taken into account. The instantaneous frequencies of the structural system are determined from the undamped system. In this paper the influence of relative thickness of the elastic case on acoustic stability of the lowest radial mode is discussed. It is found that in the early part of the burning process a thicker case makes a more stable motor. Near burnout, however, the motor becomes more stable for a thinner case.

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Effect of elastic case on stability of radial modes in solid propellant rockets

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