Study Of The Interior Ballistic Process Of Central-Gas Submunition Dispersal Research

Submunition dispersing technology is critical to the reliability and precision strike of submunition dispensers. Due to its relatively mild loading, controllable process, compact structure and other advantages, the central-gas submunition dispersal has gradually become the first choice of modern submunition dispensing systems. It is a complicated process, involving the generating and releasing process of dispersing energy, as well as the conversion process from thermodynamic energy to mechanical energy. This dissertation focuses on the interior ballistic process of central-gas submunition dispersal and studies systematically the flowing and pressure building of the gas flow field in the energy conversion chamber, the launching of the energy conversion device, and the action-and-motion process of bullets, through a combination of means such as theoretical analysis, numerical simulation and experiment. Based on the above work, attempts were made to elaborate on the stress state and movement characteristics of bullets under different characteristic parameters and reveal the influencing mechanism of characteristicstructural parameters on the stress state of bullets. Main research work and results are shown as follows:1 Experimental devicesalong with a research proposal were designed for the study of the interior ballistic process of central-gas submunition dispersal in the constant volume phrase, using 2# small-grain black powder as the ignition powder and 2/1 camphor standard powder as the dispersing powder. By testing pressure data shown in feature positions on the dispersing experimental devices, a preliminarily discussion was made on the pressure distribution rule in the energy conversion chamber. Experimental results from the same powder charge scheme indicated that the experimental device was safe and reliable, and the powder charge design was reasonable and feasible. The experiment had good reproducibility. All the work laid a solid foundation for experimental research on the dispersing process in the constant volume phase.2 Mathematical models were built according to the interior ballistic process of central-gas submunition dispersal in the constant volume phrase in combination with relevant theories on combustion, interior ballistics and aerodynamics. To facilitate the modeling and analysis of the dispersing process, the whole physical process was divided into three computing zones according to the structural characteristics of the system and the functional characteristics of all modules, namely, the black powder combustion zone in the igniter tube, the propellant powder combustion zone in the central tube, and the solid-gas two-phase flow zone in the constant-volume energy conversion chamber. Three models, including a zero-dimensional powder combustion model, a one-dimensional two-phase flow model and a two-dimensional axial-radical two-phase flow model, were built for the three zones. Meanwhile, a simulation computing program was developed based on a structured grid and CE/SE algorithm. The feasibility and accuracy of the numerical models and methods were verified by comparing the calculation results with the experimental results.3 After analyzing the numerical simulation results, flow characteristics and pressure distribution within the energy conversion chamber during the interior ballistic dispersing process in the constant volume phase were discussed. Research results showed that there was a vortex on both upper and lower sides of the flow field. The existence of the vortex created a low-pressure area in the flow field, while the low-pressure area would affect the stress state of the energy conversion device.4 Based on the experiment on the interior ballistic dispersing process in the constant volume phase, experimental devices and proposals were designed for the experiment on the entire process of the interior ballistic dispersing process. One proposal among them was to increase a spoiler in the energy conversion chamber. By testing the pressure data of characteristic positions on the dispersing device, the overload data of bullet ends and the bullet motion process captured by high-speed photography, initial information was obtained about the influence of typical structural parameters of the dispersing device on the stress state and motion characteristics of bullets.5 Relying on the mathematical models for the interior ballistic dispersing process in the constant volume phase, a flow model was built for the energy conversion chamber at transfiguration, an expansion and deformation model for the energy conversion device, and an action and motion model for bullets, according to the structural characteristics of the experimental device for the entire interior ballistic dispersing process and the physical phenomena occurring during the experimental process. A highly efficient moving mesh method, applicable to two-dimensional structured grids, was also developed. According to the CE/SE algorithm based on orthogonal quadrilateral mesh, a CE/SE algorithmwas derived for non-orthogonal quadrilateral meshes. After simulating calculation, the feasibility and accuracy of the model and algorithm were verified by comparing the calculation results with the experimental test results.6 With the distribution positions of holes of central tubes and the structural dimensions of different types of spoilers as the characteristic parameters, systematic analysis was made after simulating calculation about the stress state and movement characteristics of bullets under different characteristic parameters, so as to reveal the influencing mechanism of characteristic parameters on the action-and-motion process of bullets and propose technical methods and effective measures to improve and control the flipping movement of bullets, and then create a structural optimization design and establish a theory-based analysis method for the central-gas submunition dispensing system.This dissertation provides not only experimental and theoretical methods for the study of the interior ballistic process of central-gas submunition dispersal, but also a theoretical basis and reference for the design and optimization of similar submunition dispensing systems. Research results are of great significance in enriching the research means forsubmunition dispensers and improving the research efficiency.