Combustion of metal agglomerates in a solid rocket core flow

Maggi, F.; Dossi, Stefano; DeLuca, Luigi T.

doi:10.1016/j.actaastro.2012.04.036

Cited by 37 publications

(17 citation statements)

References 14 publications

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“…The conversion of an aluminum particle to an effectively inert aluminum oxide (Al2O3) particle would potentially slow the regression rate down to zero. On the other hand, agglomeration of some molten particles within the propellant may take place near the burning surface, and thus, effectively larger particles, to some degree, may be entering into the central flow [23]. That being said, results for the most part using the nominal evaporation law value of two for np will be shown later in this paper, as a point of reference for future comparison.…”

Section: Numerical Modelmentioning

confidence: 99%

“…In practice, one may observe the value of np becoming lower as the particle diameter falls below a certain threshold size, in some cases with np approaching unity at some point [23]. The conversion of an aluminum particle to an effectively inert aluminum oxide (Al2O3) particle would potentially slow the regression rate down to zero.…”

Section: Numerical Modelmentioning

confidence: 99%

“…That being said, results for the most part using the nominal evaporation law value of two for np will be shown later in this paper, as a point of reference for future comparison. Other particle regression models, such as the semi-empirical model proposed by Beckstead [22,23], may prove more accurate when making direct comparisons to experimental firing data for some motors employing an aluminized propellant. For this study, the nominal aluminum particle regression rate is set as 3 mm/s when it is at a particle diameter of 30 m, as a point of reference, as reflected by Figure 2.…”

Section: Numerical Modelmentioning

confidence: 99%

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Numerical Evaluation of the Use of Aluminum Particles for Enhancing Solid Rocket Motor Combustion Stability

Greatrix

2015

Energies

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Abstract:The ability to predict the expected internal behaviour of a given solid-propellant rocket motor under transient conditions is important. Research towards predicting and quantifying undesirable transient axial combustion instability symptoms typically necessitates a comprehensive numerical model for internal ballistic simulation under dynamic flow and combustion conditions. On the mitigation side, one in practice sees the use of inert or reactive particles for the suppression of pressure wave development in the motor chamber flow. With the focus of the present study placed on reactive particles, a numerical internal ballistic model incorporating relevant elements, such as a transient, frequency-dependent combustion response to axial pressure wave activity above the burning propellant surface, is applied to the investigation of using aluminum particles within the central internal flow (particles whose surfaces nominally regress with time, as a function of current particle size, as they move downstream) as a means of suppressing instability-related symptoms in a cylindrical-grain motor. The results of this investigation reveal that the loading percentage and starting size of the aluminum particles have a significant influence on reducing the resulting transient pressure wave magnitude.

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Section: Numerical Modelmentioning

confidence: 99%

Section: Numerical Modelmentioning

confidence: 99%

Section: Numerical Modelmentioning

confidence: 99%

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Numerical Evaluation of the Use of Aluminum Particles for Enhancing Solid Rocket Motor Combustion Stability

Greatrix

2015

Energies

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“…The combustion of a metal drop is a relatively slow process for which the duration can become comparable to the characteristic residence time inside the combustion chamber, if large agglomerates are present [5]. The expulsion from the nozzle of partially oxidized metal particles is a troublesome event leading to specific impulse losses.…”

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confidence: 99%

Pocket Model for Aluminum Agglomeration Based on Propellant Microstructure

Maggi

DeLuca

Bandera³

2015

AIAA Journal

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The propellant microstructure is addressed for the interpretation and the prediction of agglomerate size distribution in aluminized composite solid rocket propellants. Although the mixing process of a propellant is intrinsically random, repetitive fuel-rich local structures (pockets) are generated in the bulk. Pockets are privileged locations for agglomerate generation. In the present work, second-order spatial statistics are applied to model propellants for the characterization of the microstructure and for the definition of an agglomeration model. The model propellants used in this work are generated by a packing code on the basis of real formulations, which are experimentally characterized for validation purposes. The average size and the metal content of the pockets are derived from the interpretation of the radial distribution function. The model is capable of predicting the size distribution of the incipient agglomerates for given propellant microstructures, using one free parameter for the tuning. The fitting of experimental agglomeration data from four different industrial propellants suggests that the free parameter can be expressed as a power function of the combustion pressure and that the microstructure agglomeration model produces particle distributions that reasonably match with the experimental data

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“…The final formulation is usually a compromise between 10-14% of binder, 60-80% of oxidizer and up to 20% of metal [5,6]. When metalized propellants burn, a complex process of aggregation to agglomeration takes place at the burning surface.…”

Section: Introductionmentioning

confidence: 99%

Optimization of Potassium Nitrate Based Solid Propellant Grains Formulation Using Response Surface Methodology

Ogunleye¹,

Hammed²,

Alagbe³

2015

Adv. Sci. Technol. Res. J.

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This study was designed to evaluate the effect of propellant formulation and geometry on the solid propellant grains internal ballistic performance using core, bates, rod and tubular and end-burn geometries. Response Surface Methodology (RSM) was used to analyze and optimize the effect of sucrose, potassium nitrate and carbon on the chamber pressure, temperature, thrust and specific impulse of the solid propellant grains through Central Composite Design (CCD) of the experiment. An increase in potassium nitrate increased the specific impulse while an increase in sucrose and carbon decreased specific impulse. The coefficient of determination (R 2 ) for models of chamber pressure, temperature, thrust and specific impulse in terms of composition and geometry were 0.9737, 0.9984, 0.9745 and 0.9589, respectively. The optimum specific impulse of 127.89 s, pressure (462201 Pa), temperature (1618.3 K) and thrust (834.83 N) were obtained using 0.584 kg of sucrose, 1.364 kg of potassium nitrate and 0.052 kg of carbon as well as bate geometry. There was no significant difference between the calculated and experimented ballistic properties at p < 0.05. The bate grain geometry is more efficient for minimizing the oscillatory pressure in the combustion chamber.

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Combustion of metal agglomerates in a solid rocket core flow

Cited by 37 publications

References 14 publications

Numerical Evaluation of the Use of Aluminum Particles for Enhancing Solid Rocket Motor Combustion Stability

Numerical Evaluation of the Use of Aluminum Particles for Enhancing Solid Rocket Motor Combustion Stability

Pocket Model for Aluminum Agglomeration Based on Propellant Microstructure

Optimization of Potassium Nitrate Based Solid Propellant Grains Formulation Using Response Surface Methodology

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