Temperature and pressure sensitivity of aluminized propellants

Renie, J.; Osborn, J. R.

doi:10.2514/6.1980-1166

Cited by 9 publications

(5 citation statements)

References 9 publications

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“…Qualitatively, the experimental data also follows trends similar to studies of aluminized propellants performed by [26] and verifies models presented by [27,28] where the authors argue that the temperature sensitivity of aluminized propellants is driven by 1) aluminum powder acting as a heat sink in the condensed phase; higher concentrations reduce temperature sensitivity, and 2) burning aluminum radiating heat back to the surface; higher aluminum content increases the pressure exponent n, and p . Inspection of the experimental data indicates that propellant B3 clearly follows mechanism 1 since the sensitivity is low despite having a high n, whereas B1 and B2 illustrate a balance between the two mechanisms: a transition is clearly present.…”

Section: Resultssupporting

confidence: 84%

Validation of Numerical Simulations for Nano-Aluminum Composite Solid Propellants

Yan¹,

Son²,

Jackson³

et al. 2011

Journal of Propulsion and Power

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Nano-Aluminum is of interest as an energetic additive in composite solid propellant formulations for its demonstrated ability to increase combustion efficiency and burning rate. However, due to the current cost of nanoaluminum and the safety risks associated with propellant testing, it may not always be practical to spend the time and effort to mix, cast, and thoroughly evaluate the burning rate of a new formulation. To provide an alternative method of determining this parameter, numerical methods have been developed to predict the performance of nanoaluminum composite propellants, but these codes still require thorough validation before application. For this purpose, six propellant compositions were formulated, fully characterized, and burning rates were measured at several pressures between 34.0 and 129.3 atmospheres at room temperature, 20 C, and at an elevated temperature of 71.1 C to test the code's ability to predict pressure-dependent burning rate and temperature sensitivity. To ensure the most accurate model possible, special emphasis was placed on characterizing the size distribution of the constituent nano-aluminum and ammonium perchlorate powders through optical diffraction or optical imaging techniques. Experimental burning rate is compared with the propellant combustion model and shows excellent agreement within 5% for a range of formulations and pressures, however, under other conditions the model deviates by as much as 21%. An analysis of the results suggests that the current framework of the numerical model is unable to accurately simulate all the combustion physics of high-aluminum content propellants, and suggestions for improvements are identified.

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Section: Resultssupporting

confidence: 84%

Validation of Numerical Simulations for Nano-Aluminum Composite Solid Propellants

Yan¹,

Son²,

Jackson³

et al. 2011

Journal of Propulsion and Power

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“…Regardless of observations and postulates about the lack of aluminum combustion heat feedback affecting the burn rate in higher burn rate AP propellants, the relatively low-burn rates and large, "slow-lifting" agglomerates of the propellants studied here apparently do influence the burn rate. This trend supports the Petite Ensemble Model as extended for aluminum, 16 rather than the approaches that consider aluminum merely as a heat sink. This is consistent with the greater sensitivity to acceleration of the burning process and the higher burn rate of the bimodal at the same average distribution.…”

Section: Ap Average Particle Sizementioning

confidence: 92%

“…As noted by Miller 15 and Osborn, 16 these effects can be summarized as a combination of the changes due to the average AP size and the width of the particle size distributions. In general, the larger the average size of the AP, the more agglomeration and the lower the burn rate.…”

Section: Ap Average Particle Sizementioning

confidence: 98%

“…16 ' 19 A majority of the close-in flame combustion occurred in the portion of the diffusion flame controlled by the finest particles of AP present. Ignition of the aluminum particles within the pocket between the coarser AP particles tended to be very slow unless a significant amount of fine AP was blended with the aluminum within those pockets.…”

Section: Agglomeration Of Almentioning

confidence: 99%

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Low Burning Rate Aluminized Propellants in Acceleration Fields

Brundige¹,

Caveny

1984

AIAA Journal

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To reduce slag formation and burning rate increases, the effects of radial acceleration (up to 20 g) and low pressure (2-7 MPa) on the combustion of low-burning rate aluminized propellants (87 formulations) were investigated. Experiments were performed to obtain agglomerate size distribution, slag formation, and burning rate data. Data sources included photographs under cross flow and acceleration conditions, scanning electron probe (Cl and Al) images, particle collection combustors, and rocket motors. The tendency to form slag increases as the agglomeration size at the burning surface increases. A lower burning rate increases acceleration effects. However, residue formation is more sensitive to formulation than is burning rate; for example, bimodal vs trimodal AP can cause significant changes in residue in the absence of burn rate changes; RDX produces larger agglomerates than HMX. Through understanding obtained from this research, reduction in agglomeration, slag formation, and burning rate augmentation are directly attributable to systematic changes in formulation ingredient levels and sizes.

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“…We know from the discussion in section 3.1 that SAl×s acting place locates on the combustion surface and its approaching area, where the surface-melting layer forms when the propellant burns. Since the temperature of this layer is between 600 and 900 K (5) , and SAl will significantly release heat near 600 8C (illustrated in Figure 1), the effect of SAl to raise the propellant×s burning rate is therefore attributed to SAl×s combustion and its released heat. During the combustion process, the thickness of the surface-melting layer will decrease with the increase of pressure, so will the condensed-phase reaction fraction.…”

Section: Thermal Analysis Of Powdered Aluminummentioning

confidence: 99%

Experimental Research of the Effects of Superfine Aluminum Powders on the Combustion Characteristics of NEPE Propellants

Fang

2002

Propellants, Explosives, Pyrotechnics

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The combustion behavior of grading aluminum powders containing superfine aluminum powder (SAl) in NEPE propellant has been studied by several kinds of experimental techniques. The results indicate that the usage of grading aluminum powders containing SAl can effectively improve the combustion characteristics of NEPE propellant and the combustion efficiency of aluminum. The reason is that SAl has the different combustion and thermochemical properties from those of generally powdered aluminum (Al). SAl is inclined to burn in a single step, hence greatly increasing the heat released during the thermal decomposition of NEPE propellant.

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Temperature and pressure sensitivity of aluminized propellants

Cited by 9 publications

References 9 publications

Validation of Numerical Simulations for Nano-Aluminum Composite Solid Propellants

Validation of Numerical Simulations for Nano-Aluminum Composite Solid Propellants

Low Burning Rate Aluminized Propellants in Acceleration Fields

Experimental Research of the Effects of Superfine Aluminum Powders on the Combustion Characteristics of NEPE Propellants

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