Effect of binder melt flow on the leading edge flames of solid propellant sandwiches

Gnanaprakash, K.; Chakravarthy, Sukumar

doi:10.1016/j.proci.2018.06.071

Cited by 15 publications

(8 citation statements)

References 18 publications

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“…When the laser starts to radiate, the upper surface of the propellant begins to decompose by heat, and the oxidant and adhesive on the surface begin to decompose to produce gas. Because the rapid decomposition of the AP causes all the flames to spray upward, forming a large number of gaseous products [22]. Some aluminum particles begin to fly off the burning surface.…”

Section: Resultsmentioning

confidence: 99%

“…In recent years, some studies have found that adjusting propellant formulation can also improve the agglomeration characteristics of aluminum particles. For example, increase the concentration of ammonium perchlorate(AP, NH 4 ClO 4 ), reduce the metal content, change the RDX content [19], introduce catalyst [20] or adjust the performance of binder [21,22] to ameliorate the combustion and agglomeration characteristics of propellant. Researchers have also found that the addition of new materials has a significant impact on the agglomeration of aluminum particles.…”

Section: Introductionmentioning

confidence: 99%

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Experimental Investigation on Combustion Characteristics and Agglomeration of Al/NEPE Propellants

Zhang

Feng³

et al. 2021

Propellants Explo Pyrotec

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In order to understand the ignition and combustion characteristics of NEPE propellants under different pressure conditions and the agglomeration behavior of aluminum particles on the burning surface, the Al/NEPE propellant was tested on a sealed high-pressure laser ignition platform. Laser ignition experiments show that both ignition delay time and combustion time are inversely proportional to ambient pressure. With the increase of pressure, the reduction of ignition delay time and self-sustaining combustion time is reduced. The impact of pressure on ignition and combustion is very complex. We then analyze the effect of pressure on ignition delay time using a theoretical mechanism. High-speed microscopic images display the agglomeration of aluminum particles in propellants mainly through the following three processes: accumulation, aggregation, and agglomeration. It is also found that many aluminum particles are agglomerated on the surface, the aluminum droplet agglomerates formed on the combustion surface are separated from the combustion surface, and the agglomerates rupture and flow out of the liquid alumina during the combustion process. The phenomenon of secondary agglomeration is also observed. The microstructure and elemental composition of combustion products of aluminum particles in NEPE propellant were obtained by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). The detection results confirmed some agglomeration phenomena. At 3.0 MPa, the combustion of the propellant sample is sufficient, and the aluminum particles are smooth spherical alumina particles. At 1.0 MPa, the combustion of the propellant sample is insufficient, and the aluminum particles are rough. The particle size under different pressure was analyzed by a laser particle size analyzer. The results show that increasing the pressure can reduce the average agglomeration size of aluminum particles and improve combustion efficiency. The number of large particle aggregates is more at 3 MPa. From the perspective of overall particle size results, within the same diameter interval, the percentage of particle number does not increase or decrease significantly with the increase of pressure.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experimental Investigation on Combustion Characteristics and Agglomeration of Al/NEPE Propellants

Zhang

Feng³

et al. 2021

Propellants Explo Pyrotec

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“…Therefore, to better understand the interactions between oxidizer and binder, sandwich structures provide a simplified yet nontrivial case study. Sandwich structures have been examined in a variety of experimental reports, such as studied with and without catalysts and the influence of the liquid phase [55][56][57][58][59][60][61], over the span of the past several decades. The geometry of sandwich structures is simple: a laminate of binder between two blocks of AP (Fig.…”

Section: Ap and Pban Sandwichmentioning

confidence: 99%

A diffuse interface method for solid-phase modeling of regression behavior in solid composite propellants

Kanagarajan¹,

Quinlan²,

Runnels³

2022

Preprint

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Solid composite propellants (SCPs) are ubiquitous in the field of propulsion. In order to design and control solid SCP rocket motors, it is critical to understand and accurately predict SCP regression. Regression of the burn surface is a complex process resulting from thermo-chemical-mechanical interactions, often exhibitingextreme morphological changes and topological transitions. Diffuse interface methods, such as phase field (PF), are well-suited for modeling processes of this type, and offer some distinct numerical advantages over their sharp-interface counterparts. In this work, we present a phase-field framework for modelingthe regression of SCPs with varying species and geometry. We construct the model from a thermodynamic perspective, leaving the base formulation general. A diffuse-species-interface field is employed as a mechanism for capturing complex burn chemistry in a reduced-order fashion, making it possible to model regressionfrom the solid phase only. The computational implementation, which uses block-structured adaptive mesh refinement and temporal substepping for increased performance, is briefly discussed. The model is then applied to four test cases: (i) pure AP monopropellant, (ii) AP/PBAN sandwich, (iii) AP/HTPB sandwich,and (iv) spherical AP particles packed in HTPB matrix. In all cases, reasonable quantitative agreement is observed, even when the model is applied predictively (i.e., no parameter adjustment), as in the case of (iv). The validation of the proposed PF model demonstrates its efficacy as a numerical design tool for future SCP investigation.

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“…At present, the main problem of Al particles as a metal fuel is the performance degradation caused by their own agglomeration [8] . There are two main solutions to reduce the particles agglomeration of Al in the propellant: one is to modify the surface of the Al particles to achieve faster combustion while making the Al particles smaller; the other is to adjust the propellant metal fuel [9][10] . By adding other elements to the formula to suppress the agglomeration of Al powder, the combustion is more thorough.…”

Section: Introductionmentioning

confidence: 99%

Combustion characteristics of Al-Li alloy powder and its application in solid propellant

Zhou,

Huang,

Liu

et al. 2023

J. Phys.: Conf. Ser.

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This article is focused on the analysis of Al-Li alloy powder’s thermal oxidation reactivity. The Scanning electron microscope (SEM) analysis results show that the Al-Li particles are uniform and spherical. The phase transformation of the Al-Li alloy powder during the oxidation process was characterized by X-ray Diffraction (XRD), the phase composition of the oxide alloy particles is mainly oxides such as LiAlO2 and LiAl5O8, indicating that the particles are fully burned. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TG) are performed coupled with thermodynamic calculations. The analysis results show that Li can reduce the activation energy required for the powder reaction, promote the combustion of Al powder, reduce the ignition temperature, and make the particles begin to oxidize at low temperature. At the same time, Li can shorter the ignition time of Al-Li alloy particles and improve the particles or propellant combustion characteristics. The results of this work demonstrate that fuel particle engineering for more complete combustion and energy conversion can be achieved by adding other elements and changing the powder formulation.

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Effect of binder melt flow on the leading edge flames of solid propellant sandwiches

Cited by 15 publications

References 18 publications

Experimental Investigation on Combustion Characteristics and Agglomeration of Al/NEPE Propellants

Experimental Investigation on Combustion Characteristics and Agglomeration of Al/NEPE Propellants

A diffuse interface method for solid-phase modeling of regression behavior in solid composite propellants

Combustion characteristics of Al-Li alloy powder and its application in solid propellant

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