Solid-Propellant Combustion Response Function from Direct Measurement Methods: ONERA Experience

Cauty, Franck

doi:10.2514/2.5503

Cited by 13 publications

(6 citation statements)

References 4 publications

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“…The experimental results of Horton & Price (1963), Traineau, Prevost & Tarrin (1994) and Cauty (1999) show how the solid admittance function has a peak value, higher than (γ + 1)/γ 1.77, in the frequency range of 100 Hz to 3000 Hz, which belongs to the low-frequency domain corresponding to the longitudinal modes. Notice that if the classical result for A b 0 = n g − 1 < 0, as given by the linearization of the St. Robert's law, is used instability can never be achieved.…”

Section: Discussion Of the Results And Stability Domainmentioning

confidence: 99%

Longitudinal acoustic instabilities in slender solid propellant rockets: linear analysis

García-Schäfer¹,

Liñán²

2001

J. Fluid Mech.

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To describe the acoustic instabilities in the combustion chambers of laterally burning solid propellant rockets the interaction of the mean flow with the acoustic waves is analysed, using multiple scale techniques, for realistic cases in which the combustion chamber is slender and the nozzle area is small compared with the cross-sectional area of the chamber. Associated with the longitudinal acoustic oscillations we find vorticity and entropy waves, with a wavelength typically small compared with the radius of the chamber, penetrating deeply into the chamber. We obtain a set of differential equations to calculate the radial and axial dependence of the amplitude of these waves. The boundary conditions are provided by the acoustic admittance of the propellant surface, given by an existing analysis of the thin gas-phase reaction layer adjacent to the solid-gas interface, and of the nozzle, accounting here for the possible effect of the vorticity and entropy waves. The equations are integrated in closed form and the results provide the growth rate of the disturbances, which we use to determine the conditions for instability of the longitudinal oscillations. IntroductionThe purpose of this paper is to clarify the role of the vorticity and entropy waves that accompany acoustic oscillations in solid rocket motors in their acoustic instabilities. With this aim, we shall consider the simple case of an axis-symmetric configuration, in which the solid propellant is of cylindrical shape, bounded externally by an enclosure and with a cylindrical gaseous cavity of circular shape inside. The cavity is closed at one end by an endwall and the other end is attached to a nozzle, where the gases generated by the combustion process in the internal surface of the propellant are accelerated to supersonic speeds.If the Mach number in the nozzle throat is close to unity, the ratio of its area, A t , to the internal surface area, A s , of the propellant bounding the cavity must be, as derived from mass conservation considerations, of the order of the Mach number M b = V b /c b of the gaseous combustion products leaving, with velocity V b , the thin reaction layer adjacent to the surface of the propellant. M b 1, because V b is typically of the order of 1 m s −1 , very small compared with the sound velocity c b of the burned gases. Due to the small value of A t /A s , the attenuation of any acoustic oscillations that may be excited in the nearly closed gaseous cavity is very weak, and this may contribute to the existence of combustion instabilities in the chamber. The analysis of the acoustic instabilities has received considerable attention in the literature; see, for example, the

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Section: Discussion Of the Results And Stability Domainmentioning

confidence: 99%

Longitudinal acoustic instabilities in slender solid propellant rockets: linear analysis

García-Schäfer¹,

Liñán²

2001

J. Fluid Mech.

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“…In the framework of solid-propellant combustion diagnostics, most of the classical experimental techniques are devoted to studies of the solid phase; namely, burning rate with, i. e., ultrasound technique [1], pressure measurement coupled to indirect or direct techniques and/or analysis methods (unsteady behavior) [2]. Studied here is the combustion of solid composite propellants which are a mixture of several ingredients such as ammonium perchlorate (AP), hydroxyl-terminated polybutadiene (HTPB) binder, and metallic loads like Aluminum particles.…”

Section: Introductionmentioning

confidence: 99%

Light deviation based optical techniques applied to solid propellant combustion

Cauty

Eradès

Desse

2011

Progress in Propulsion Physics

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The Investigation in Combustion of Energetic Materials (InCoME) program is aimed at validating the numerical simulation of composite propellant combustion using nonintrusive optical techniques. The Focusing Schlieren Technique (FST) was selected; it allows catching light deviation from a thin vertical planar section centered above the propellant combustion surface. The optical system is described in the paper. Signi¦cant results are presented showing the capabilities of this technique when applied to solid propellant combustion in terms of studying §ame structure, §ame propagation, and particle tracking.

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“…Instability research, therefore, requires the use of a nonlinear approach, as the powders themselves are nonlinear systems with certain eigenfrequences and decay rates. Response functions were obtained in experiments by finding the dynamic characteristics of the burning rate; the disturbances were mainly initiated by radiative heat pulses and pressure oscillations in a T-chamber [11][12][13][14][15][16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Nonlinear response functions of the burning rate of ballistite powders

Зенин

Finjakov

2008

Combust Explos Shock Waves

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Second-order nonlinear response functions to pressure oscillations are calculated for a group of ballistite powders with additives, based on results of microthermocouple measurements. A unified law of gasification of ballistite powders is refined. A classification of nonlinear response functions is proposed: viscous, normal, and critical response functions are identified. More than half of the burning regimes of these powders are demonstrated to have a viscous response type with a weak dependence on frequency and with a weakly expressed maximum in the case of a resonance. The effect of the powder composition on the nonlinear response functions is analyzed. Specific features of the nonlinear response as a function of a new parameter (phase shift between the interacting modes) are considered. It is shown that the errors in determining the nonlinear response functions depend on the response type and have low values for the majority of the burning regimes. Arguments in favor of the process one-dimensionality in the reactive layer of the condensed phase are given. A hypothesis of the near-critical state of some products of decomposition in this layer is proposed.

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Solid-Propellant Combustion Response Function from Direct Measurement Methods: ONERA Experience

Cited by 13 publications

References 4 publications

Longitudinal acoustic instabilities in slender solid propellant rockets: linear analysis

Longitudinal acoustic instabilities in slender solid propellant rockets: linear analysis

Light deviation based optical techniques applied to solid propellant combustion

Nonlinear response functions of the burning rate of ballistite powders

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