Separation Behavior of Pyrotechnically Actuated Device Considering Small-Volume Effect of Combustion Chamber

Hwang, Dae-Hyun; Han, Doo-Hee; Han, Jae‐Hung; Sung, Hong-Gye; Ryu, Byungtae

doi:10.2514/1.a34656

Cited by 5 publications

(3 citation statements)

References 14 publications

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“…In a very small initial volume, the energy efficiency, η p , can be varied due to incomplete combustion and interaction with the inner surface of the chamber. To obtain a precise prediction, the energy efficiency was evaluated by a series of experiments with small chambers [11].…”

Section: A Combustion Modelmentioning

confidence: 99%

See 1 more Smart Citation

Performance Optimization of a Split-Type Low-Shock Separation Bolt

Hwang

Han

Lee

et al. 2021

Journal of Spacecraft and Rockets

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Section: A Combustion Modelmentioning

confidence: 99%

“…To effectively simulate the multiple contacts, a virtual spring and a damper, described in Eq. (11), are considered between the three interactions (bolt-splits, housing-splits, and piston-splits). The stiffness and damping coefficients were empirically determined.…”

Section: Surface Interaction Modelingmentioning

confidence: 99%

Performance Optimization of a Split-Type Low-Shock Separation Bolt

Hwang

Han

Lee

et al. 2021

Journal of Spacecraft and Rockets

Self Cite

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“…Han et al [20] modeled the combustion of ZPP in a closed vessel by applying the Rosin-Rammler distribution [28], considering the cumulative mass of all the granules. Based on this size distribution, Hwang et al [29] proposed a precise analytical model for pyrotechnically actuated devices by investigating the combustion characteristics of ZPP charged in a small volume chamber. In most of the works, the impact of initiator metal cap, bridge wire, and grain size distribution and their sensitivity on the design of the device was not mentioned, which is, however, crucial for product development.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of Pyrotechnical Initiators and Their Impact in Airbag Inflator Applications: Ballistic Modeling and Functional Analysis

Chang¹,

Sadiki²

2021

JEPT

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A numerical model describing the ballistic behavior of a commercially used initiator is presented in this article. This model was built on the principle of conservation of mass and energy in the multi-phase framework incorporated with multi-loaded conditions. After obtaining the information about the grain size distribution in each composite, a fixing factor was proposed based on the surface area ratio of the composites. Thus, the solid propellant burning process based on distributed grain size was described, and the burn rate parameters of the applied pyrotechnic compositions were re-evaluated for different preconditioned temperature levels according to Vieille’s law. The influence of bridge wire and initiator metal cap was further modeled concerning their characteristic properties according to the observed measurements. The validation of the entire initiator model in the closed bomb test showed quantitative agreement with the measured pressure evolution, while the parameter study for evaluating the ballistic sensitivity of each component delivered some insights into the product development process. Furthermore, the configuration of a cold gas inflator was utilized to evaluate the initiator impact for a realistic application, where the shock wave intensity during deployment serves the main function in the inflator design. Incorporated with CFD simulations to capture the shock wave propagation, 0D-3D coupling strategy for initiator ballistics to inflator configuration was realized. Besides, the simulation results reflected the physical conditions in a proper manner. In particular, the parameter study led to a better understanding of interactions between inflator components, which were barely possible to be quantified through the measurements. The proposed initiator model could also be used in combination with other mechanical principles as a component of pyrotechnic devices such as pin-puller, electric line cutters, or airbag inflators. The detailed information gained in describing the physical properties enabled us to assess the existing design quantitatively and to have better control of the product quality.

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Understanding aging characteristics of a pyrotechnic initiator through performance modeling in Closed Bomb Tests

Jang,

Kim,

Han

2024

Propellants Explo Pyrotec

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We conducted an analysis of the natural aging characteristics of an electric pyrotechnic initiator stored for 11 years, using 10‐cm3 Closed Bomb Tests (CBTs). For the comparative analysis, we utilized the closed bomb test data from other three batches that were tested 11 years ago when they were produced. Notably, two aged samples exhibited peculiar phenomena in terms of maximum pressure and the time taken to reach it, both of which are the performance indicators of Closed Bomb Tests. The time taken to reach maximum pressure increased in both aged samples compared to the pristine samples. Additionally, while one aged sample demonstrated a higher maximum pressure, the other displayed a significantly lower value compared to the pristine ones. Through statistical analysis of test results from three batches of the reference samples and one batch of aged samples led us to propose the existence of a natural aging effect on the initiator. The increase in time taken to reach maximum pressure compared to the reference samples can be attributed to the phenomenon of an increasing particle size distribution of spherical combustion particles in the present combustion model. Furthermore, the aging of the binder of the initiator charge likely contribute to a relative increase in the size of the combustion particles due to the binder hardening over time. To explain the phenomenon of the pressure initially reaches its maximum value on the CBT pressure‐time curve and subsequently decrease, we introduce the concept of condensation, where the gas phase transitions into liquid and solid phases.

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Separation Behavior of Pyrotechnically Actuated Device Considering Small-Volume Effect of Combustion Chamber

Cited by 5 publications

References 14 publications

Performance Optimization of a Split-Type Low-Shock Separation Bolt

Performance Optimization of a Split-Type Low-Shock Separation Bolt

Numerical Investigation of Pyrotechnical Initiators and Their Impact in Airbag Inflator Applications: Ballistic Modeling and Functional Analysis

Understanding aging characteristics of a pyrotechnic initiator through performance modeling in Closed Bomb Tests

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