Effects of Mg/PTFE pyrotechnic compositions on reignition characteristics of base bleed propellants and heating mechanism

Xue, Xiaochun; Ma, Longze; Yu, Yonggang

doi:10.1016/j.dt.2020.11.016

Cited by 8 publications

(6 citation statements)

References 22 publications

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“…Thus the heat flux also moves up, which implies that the igniter combustion gas can provide more heat to the extinguished AP/HTPB. Once the extinguished AP/ HTPB surface reaches the ignition temperature through heating, 11 more combustion gas is generated by the chemical reaction and then released into the projectile to fill the gas rarefaction region of the projectile base and subsequently improve the velocity of the projectile. After 2.0 ms, as the BBU is gradually filled with the igniter combustion gas, the temperature is uniformly distributed on the AP/HTPB surface.…”

Section: Convective Heat Transfer Characteristicsmentioning

confidence: 99%

“…Consequently, the following assumptions are provided to establish the model: At the computational initial time, when the projectile moves from the muzzle to the ambient air, the AP/HTPB propellant in the BBU is assumed to extinguish, according to Xue et al 11 The pyrotechnic composition in the igniter is still in the combustion state, 38 generating Mg vapor and C 2 F 4 gas as the initial reactant of the gas phase in the unit. …”

Section: Mathematical Modelmentioning

confidence: 99%

“…At the computational initial time, when the projectile moves from the muzzle to the ambient air, the AP/HTPB propellant in the BBU is assumed to extinguish, according to Xue et al 11 …”

Section: Mathematical Modelmentioning

confidence: 99%

“…[7][8][9][10] In addition, the BBU of the aerodynamic vehicle experiences a rapid depressurization process, which causes the strong gas-gas interaction appears to be under the combined action of the muzzle flow effect. 11 This gas-gas interaction at high temperature is a comprehensive action, including energy conversion and mass transfer repeatedly. Finally, the complex flow structure makes the energy conversion mechanism and thermal characteristics of the flow field more complicated.…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, the propellant gas at approximately 2000 K in the main body (namely, “muzzle” in the following sections) and in the BBU, is released into the atmosphere simultaneously with the supersonic vehicle moving from the muzzle, generating an unsteady muzzle flow, which contains many undesired phenomena, such as blast waves, electromagnetic radiation, flash and smoke of the muzzle, and energy exchange 7–10 . In addition, the BBU of the aerodynamic vehicle experiences a rapid depressurization process, which causes the strong gas–gas interaction appears to be under the combined action of the muzzle flow effect 11 . This gas–gas interaction at high temperature is a comprehensive action, including energy conversion and mass transfer repeatedly.…”

Section: Introductionmentioning

confidence: 99%

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Investigation of thermal performance in dual‐fuel units

Xue

2022

Energy Science & Engineering

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Numerical studies were carried out to investigate the thermal performance of the muzzle flow with strong shock discontinuities and gas-gas heat transfer mechanism in the base bleed unit (BBU) of an aerodynamic vehicle under the combined effects of muzzle flow and depressurization process. The process was modeled using the Navier-Stokes equations with chemical kinetics and interior ballistic equations. The results show that the muzzle phenomena with large temperature gradients and different wave structures appear after the supersonic vehicle enters into the free-flight stage. The BBU also experiences a strong depressurization process with the release of high-temperature propellant gas at 2200 K. However, the igniter combustion gas at a higher temperature of 3050 K in the BBU develops downstream and upstream repeatedly under the combined effects of the base wave and depressurization process, which makes the energy conversion process in the unit more complicated. With the projectile leaving the control of the muzzle flow, the BBU is full of the igniter combustion gas and the energy in the unit is uniformly distributed gradually. The high-temperature area, at approximately 2750 K, propagates downstream along the axial and radial directions simultaneously until it finally dominates the entire unit. The maximum temperature of the combustion gas acting on the propellant surface is always 2740 K and the maximum heat flux remains approximately 1250 W/cm 2 at later periods.

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Section: Convective Heat Transfer Characteristicsmentioning

confidence: 99%

Section: Mathematical Modelmentioning

confidence: 99%

“…At the computational initial time, when the projectile moves from the muzzle to the ambient air, the AP/HTPB propellant in the BBU is assumed to extinguish, according to Xue et al 11 …”

Section: Mathematical Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Investigation of thermal performance in dual‐fuel units

Xue

2022

Energy Science & Engineering

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Exploring the potential of boron carbide in enhancing energy output of solid fuels for SFRJ and hybrid rocket propulsion systems

Nithya Mahottamananda,

Pal,

Alay Hashim

et al. 2023

Propellants Explo Pyrotec

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Boron carbide (B4C) is known for its exceptional hardness and high energy release during combustion, despite its ignition processes presents considerable challenges. This study focuses on exploring the potential of B4C as an enhancer for the energy output of solid fuels designed for hybrid rocket engines (HRE) or solid fuel ramjets (SFRJ). This study presents the successful incorporation of B4C and fluorinated PTFE (polytetrafluoroethylene) polymer into the HTPB (hydroxyl‐terminated polybutadiene) fuel matrix, aiming to enhance the ignition, combustion, and regression rate performance of solid fuel. Five different fuel compositions were formulated with varying mass ratios of B4C, and their post‐combustion products were characterized using XRD (X‐ray diffraction), HRSEM (high‐resolution scanning electron microscopy), and EDS (energy‐dispersive X‐ray spectroscopy) techniques. The HRSEM‐EDS analysis confirmed a uniform dispersion of B4C/PTFE additives throughout the HTPB matrix. To evaluate the combustion behavior of the B4C/PTFE additives, an opposite flow burner was employed with a gaseous oxygen oxidizer. The F4 fuel sample, loaded with B4C/PTFE (10/20), exhibited an average regression rate increase ranging from 0.61 to 1.15 mm/s when evaluated within the oxidizer flux range of 36–77 kg/m2s, in comparison to that of pure HTPB (0.4 mm/s to 0.76 mm/s). The ignition delay time was investigated as a key parameter affected by the B4C concentration in the solid fuel formulations. Furthermore, a comprehensive combustion mechanism is proposed and discussed for B4C/PTFE loaded in the HTPB matrix under an oxygen environment.

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