Reduced Agglomeration of Aluminum in Wide-Distribution Composite Propellants

Mullen, Jessica C.; Brewster, M. Q.

doi:10.2514/1.50127

Cited by 45 publications

(12 citation statements)

References 16 publications

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“…Sambamurthi et al 14 and Price 15 have presented data and argued based on understanding of the flame structure in the propellant combustion zone that the agglomerate size should decrease with increase in pressure as the attachment of leading edge (diffusion) flames (LEF) on fine AP particles in a propellant becomes more prevalent. Price et al 16 and Takahashi et al 9 also showed corresponding increase in propellant burning rates following the same arguments. Hence, the inverse correlation between agglomerate size and burning rate still holds.…”

Section: B Agglomerate Sizes Of Ap/al/htpb Propellantsmentioning

confidence: 66%

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Experimental Study on Combustion of Aluminum in Composite Propellant

Liu¹,

Liu²,

Jin³

2015

51st AIAA/SAE/ASEE Joint Propulsion Conference

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Used the optical methods with the long distance microscope and high-speed camera are to study the dynamic combustion process of aluminum particle on and out of the burning surface of the AP composite propellant. The experiments are all conducted in a combustion chamber under 1MPa, 3MPa and 5MPa. All the experiments use the same formulation ammonium perchlorate (AP)/ Aluminum (Al)/ cyclotrimethylene trinitramine (RDX)/ hydroxyl-terminated poly butadiene (HTPB) propellants. Based on the photos captured by camera, aluminum droplets with different particle size are observed. The flow velocity with the combustion gas is calculated. As the particle diameter increasing, the flow velocity becomes small. Under 3MPa and 5MPa the flow velocity are larger than the in 1MPa. But the flow velocity rang from 150μm to 450μm in 3MPa is close to the 5MPa. Also the weight mean Aluminum agglomerate diameter Dag is calculated. The agglomerate size generally decreases with increase in burning rate of the propellant, and that it also decreases with an increase in pressure. Also the agglomerate size range decreases. The moving motion for the agglomerates under low pressure on the burning surface has been especially observed before they separate from the surface. NomenclatureD = diameter Dag = weight mean Al agglomerate diameter N = number W = weight i = individual particles

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Section: B Agglomerate Sizes Of Ap/al/htpb Propellantsmentioning

confidence: 66%

“…In recent years, the progress of the aluminum agglomeration has been researched by optical observation 8,9 . There works are under normal pressure or low-pressure conditions (<4MPa) with AP/ HTPB propellants or AP/ ammonium nitrate (AN) Composite Propellants.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on Combustion of Aluminum in Composite Propellant

Liu¹,

Liu²,

Jin³

2015

51st AIAA/SAE/ASEE Joint Propulsion Conference

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“…The agglomeration of aluminum in solid propellant combustion has been the subject of many theoretical and experimental studies during past four decades [2][3][4][5][6][7][8][9]. Scholars around the world have long sought to solve this problem.…”

Section: Introductionmentioning

confidence: 99%

Effect of Organic Fluoride on Combustion Agglomerates of Aluminized HTPB Solid Propellant

Zhou

Zou

Huang

et al. 2017

Propellants Explo Pyrotec

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Hydroxyl‐terminated polybutadiene (HTPB) based propellants containing fixed aluminum content (18 wt %) and different amounts of organic fluoride (OF) additive were studied. Explosion heat of propellant samples and particle size distribution of the solid combustion products were experimentally measured to generally assess the effect of the organic fluoride compounds on propellants. Heats of explosion decreased approximately by 9.5 %, from 7209 (±259) to 6525 (±146) kJ kg−1, with the increase in OF content from 0 % to 6 %, and the volume fraction of particles size above 10 μm was sharply decreased. In addition, scanning electron microscope images showed the solid combustion products to be well separated, the titration analysis results also gave the amount of unburned metallic aluminum decreased. These results indicated that OF as an additive would be helpful to reduce agglomeration in the combustion products of aluminized HTPB propellants. Furthermore, a mechanism for suppression of agglomerate size can be postulated based on the X‐ray diffraction analysis data that addition of OF promotes increased content of γ‐Al2O3 (aluminum oxide) in the solid combustion products.

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“…Until now,a lmost all clear pictures about the aluminum agglomeration process on the burning surface is below 1MPa [10,25,26].L iu's experiments were conducted at 6.89 MPa by cinephotomicrography technique, but the agglomeration processw as not given [5].F igure2 depicts the aluminum particle agglomeration process under high pressure.…”

Section: Agglomerationmentioning

confidence: 96%

Aluminum Agglomeration on Burning Surface of NEPE Propellants at 3-5 MPa

Liu

et al. 2016

Prop., Explos., Pyrotech.

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Aluminum agglomeration and agglomerate sizes of NEPE propellants were studied by cinephotomicrography at pressures of 3 and 5 MPa. Accumulation, aggregation, and agglomeration of aluminum particles similar to that at pressures below 1 MPa were observed. Coalescence of two agglomerates on the burning surface is obtained for the first time. A decrease in the burning rate from 8 to 5 mm s−1 leads to about 20 % increase in the agglomerate diameter. The pressure is found to have no direct influence on the agglomerate diameter when the burning rate is kept constant. The evolution of the agglomerate diameter according to the increase of the virgin aluminum size from 16 to 36 μm is convex in shape and reached its maximum at a particle diameter of 29 μm. Increasing the amount of RDX crystals added in the propellants causes a larger agglomerate diameter. The experimental mass average agglomerate diameters were compared with various agglomeration models. It is found that Hermsen and Salita empirical models have a higher accuracy for NEPE propellants rather than Becksted, Liu, or pocket models.

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Reduced Agglomeration of Aluminum in Wide-Distribution Composite Propellants

Cited by 45 publications

References 16 publications

Experimental Study on Combustion of Aluminum in Composite Propellant

Experimental Study on Combustion of Aluminum in Composite Propellant

Effect of Organic Fluoride on Combustion Agglomerates of Aluminized HTPB Solid Propellant

Aluminum Agglomeration on Burning Surface of NEPE Propellants at 3-5 MPa

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