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To simplify the complexity of moving boundary treatment in the two-phase flow numerical simulation and improve the computational accuracy of moving boundary treatment, a two-dimensional twophase flow model based on ALE method is established. The governing equations are discretized with the TVD-type MUSCL scheme to obtain a second order accuracy in finite volume form. A two-step and fourthorder Runge-Kutta method is used to solve the source terms. The dynamic mesh update method and numerical method are verified by a standard test with the exact solution. The numerical application on a large caliber guided projectile shows the complete development and the two-phase flow characteristics of the interior ballistic process. The calculated results are in good agreement with the experimental results. The effects of different ignition conditions on interior ballistic performance are investigated. The study lays a theoretical foundation for deep optimization of the interior ballistic performance and firing safety. [ABSTRACT FROM AUTHOR]

In order to evaluate ballistic consistency under small sample circumstance, an evaluation method of ballistic consistency is proposed based on the normal distribution small sample compatibility theory. This method is to compare the calculated order statistics and the simulated critical value to determine the ballistic consistency. The main advantage is not necessary to calculate the position- scale estimate value, so it could decrease the calculation error due to small sample size. The calculation shows that this method is better than matched pair t test and probability circle sequential test under small sample circumstance (n≤5 ). [ABSTRACT FROM AUTHOR]

In order to distinguish 1 cm² copper crusher gauge, a special experimental device which can supply required pressure source by volume expansion is proposed and designed. An interior ballistic model of the device is set up and simulated based on the interior ballistic analysis and the flow equation of the working chambers. The pressure and flow characteristics of propellant gas between bore and chamber are obtained. And the influences of initial volume and position of the high pressure chamber on its maximum pressure are studied. The maximum pressure of the high pressure chamber can be adjusted to about 39.0 MPa under the condition of the known parameters. Compared with the experimental results, the maximum deviation is 4.9%. The device can meet the requirement of identifying copper crusher gauge. [ABSTRACT FROM AUTHOR]

In order to analyze the lethality of a forward enhanced lethal HE (high explosive) projectile against personnel targets, the static explosion experiments are made on the forward enhanced lethal HE projectile and the conventional HE projectile, which have same structural characteristic parameters. A calculating model of the lethality against personnel targets is established. The lethal powers of two kinds of projectile against personnel targets in same terminal conditions are comparatively calculated. The result shows that the forward enhanced lethal HE projectile can produce a fragment damage area compared with the conventional HE projectile so that it makes the killing area for personnel targets being increased by 147.3%. Its lethality against personnel targets is enhanced effectively. [ABSTRACT FROM AUTHOR]

A new prediction method based on radial basis function (RBF) neural network and an unscented Kalman filter technology is proposed for the precise and quick prediction of impact-point without exact flight data. Firstly, RBF neural network approximated external ballistics equation is used to predict the projectile impact-point, and the improved quantum-behaved particle swarm optimization algorithm is used to optimize the training method. On this basis, the tentative prediction data is processed with unscented Kalman filter. At last, the prediction simulation is carried out. The results show that a high prediction precision can be reached under the condition of input data with noise. The method proposed in this paper is efficient and available for impact-point prediction. [ABSTRACT FROM AUTHOR]

For the technical scheme of the two-dimensional trajectory correction projectiles (TDTCPs) with drag brake and despining blade, the mathematical model of two dimensional trajectory corrections is discussed based on the theory of exterior ballistics. An approximate formula for predicting the ballistic drift and trajectory correction quantity is deduced with respect to the process of lateral trajectory correction. The capability of lateral trajectory correction and the flight stability of TDTCP are also analyzed. By comparing with the results of flight test, the accuracy and effectiveness of this approximate calculation method are verified. The result of the approximate method is in accordance with those of 6DOF trajectory model and firing test, and the maximum error is no more than 40 m. All the work is valuable for further research. [ABSTRACT FROM AUTHOR]

Ballistic gelatin is used as a stimulant for human tissue in the experimental study of temporary cavity which is an important factor of ballistic injury. To study the motion of temporary cavities, the steel spheres with diameters of 3 mm, 4 mm and 4. 8 mm are fired into the gelatin blocks at 650 ~ 1 000 m/s in the experiments. The movement of temporary cavity is recorded by a high speed camera. The sine motion of the cavity wall is deducted based on the displacement field assumption and the elastic deformation assumption of gelatin. The empirical relations between amplitude and energy, and frequency and energy are established using the experimental data while a penetration model of spherical fragments in gelatin is built. The model is used to predict the temporary cavity for a 5. 2 mm tungsten sphere penetrating into gelatin at 800 m/s. The predicted results are in good agreement with the experimental data. [ABSTRACT FROM AUTHOR]

The two-phase flow mathematic models are developed for gas generator with central igniter tube. The one-dimensional two-phase model is used for the ignition of central igniter tube, and the two-dimensional two-phase model is used for the energy release of tubular gas generator. The coupling function of two tubes is established through exchange between gas and solid. The interior ballistic simulation software is programmed by Mac Cormack two-step scheme and is used to calculate the gas generator. The calculated results well accord with the test results, which proves that the model is right and provides important theory foundation to structure design and optimization on gas generator with central igniter tube. Meanwhile, the energy releasing course is analyzed based on the simulation results. The result shows that the uniform ignition condition is the precondition of gas generator releasing energy steadily. The ignition energy released uniformly could ensure the reliable burning of powders in gas generator and the release of controlled energy. [ABSTRACT FROM AUTHOR]

An improved two-phase flow model is established to simulate the interior ballistic characteristics of modular propellant charge. In this model, the constraint of the walls of modules on gas flow is taken into account. The rupture rule of combustible case and the flame spreading between different modules are also considered in the improved model. This model turned out to be reliable by comparing the numerical results with the experimental data. It can be used to predict the development of pressure waves and to diagnose the interior ballistic performance of modular propellant charge systems. The simulation results show that the flame spreads slower because the gas is constrained by the bottom walls of the center-tube. The combustible cases are ruptured in sequence, the time when the combustible cases begin to rupture until all the cases rupture is affected by the strength of the modular case and the ignition core. [ABSTRACT FROM AUTHOR]

The warship continues to move after the trajectory correction projectile is fired from shipborne gun, and the shipborne radar for trajectory measurement also continue to move and sway, and so the relative trajectory measured by radar need to be transformed into the ballistic reference frame which takes the gun muzzle as an origin during firing. The precision of transformed ballistic coordinates is influenced by the warship fluctuation and the errors of radar measuring, warship sway angles, velocity and course bearing. In order to quantify the influence of every error on the precision of ballistic coordinates, a model of precision of ballistic coordinates was set up and simulated, and some data about the influence of warship fluctuation and the errors of radar measuring, warship sway angles, velocity and course bearing on the precision of ballistic coordinates were got. [ABSTRACT FROM AUTHOR]

In order to ensure high dispersing velocity of the submunitions in the low overload dispersing environment, a new piston central dispersing mechanism was devised and working process of the dispersing mechanism was researched. The characters of this kind of mechanism were as follows : the trust force from the piston to the submunition was transmitted by the beveled sabot; the powder burned in the high-pressure chamber and the generated powder gas did work in the low-pressure chamber; the initial trust peak was reduced, and so on. According to the working principle of the piston central dispersing mechanism, the force analysis of piston, sabot and submunitions were carried out, and the interior ballistics model of the new mechanism was established. It is proved by the simulation calculation that, this new piston central dispersing mechanism not only can supply a dispersing velocity more than 50 m/s, but also can control the overload of submunitions under 1 000g. The interior ballistics model can be used to guide the design of the new piston central dispersing mechanism. [ABSTRACT FROM AUTHOR]

In order to explore the bullet proof mechanism of ceramic/steel composite armor, the ballistic impact experiment was carried out to study the dynamic response of ceramic/steel composite armor subjected to the impact of high speed fragments. The damages of projectile, ceramic and steel back plate were described physically and analyzed phenomenologically. The damage modes of ceramic and steel back plate were determined. The energy transformation during the ballistic penetration and the bullet proof performance of the ceramic/ship steel composite armor were analyzed. The results show that the conical crash is a main damage mode of ceramic under the impact of high speed fragments. And the main macro cracks are radial, ring and conical cracks which extend outward at about 65° angle included between the conical crack and the initial surface normal. Besides there are the inverse conical cracks extended outward at angle of 65° to the back surface normal. The deformation range, destructiveness and damage mode of the back plate have great different from those of ship steel target. The deformation mode of the backing plate is bulging-dishing when the impact velocity is below the ballistic limit. When the impact velocity exceeds the ballistic limit, the back plate has 3 damage modes, i. e. shearing damage, dishing-shearing-petaloid damage and dishing-petaloid damage, as the relative thickness of ceramic increases. In the penetration process of light ceramic/metal composite armor, the kinetic energy of projectile is mainly dissipated in the deformation and damage of projectile and back plate. When the velocity of the penetrator is about ballistic limit, the energy dissipated in projectile and back plate damages varies with the relative thickness of ceramic. But the total energy dissipated in these facets occupies more than 90% of initial kinetic energy of the projectile, and the energy dissipated in the fragmentation of ceramic and the ejecting kinetic energy of ceramic fragments occupies less than 10% of its initial kinetic energy. [ABSTRACT FROM AUTHOR]

Probability of perforation ( POP) curve is a constructive method to estimate the ballistic performance. It can be used to estimate the low velocity at smaller penetration probability. POP curves have potential and promising application in body armor design. For this purpose, the performance of UH- MWPE unidirectional layers (PE armor) against 7.62 mm type 51 pistol bullet was investigated. POP curves was established by logistic function and binary logistic regression. v50 (velocity with 50% penetration probability) and v05 (velocity with 5% penetration probability) of PE armor were derived from POP curves. v50 was 592 m/s determined by both methods, while v05 was 538 m/s and 514 m/s, respectively. The results indicate that the regression method is more suitable for the estimation of velocity at low penetration probability. The difference between the two POP curves was discussed. [ABSTRACT FROM AUTHOR]

A contamination prevention method using jet flow was proposed to protect the optical window in laser ignition system from attachment of combustion remains of propellants and decrease of transparence. The pressure in chamber and gas flow between the chamber and the cavity were analyzed by using interior ballistics calculation. The mathematical model of the particle movement in the chamber was established and calculated. The calculation and simulation results indicate that the new proposed method is effective to protect the optical window, the jet flow interference can reduce the particles reaching to the optical window area effectively. The structural parameters are optimized for guns with different calibers based on the simulations. A screen tube is proved to be useful to enhance the protection effect. The increases of the length of cavity or the angle of diverting orifice can lead to a better protection. [ABSTRACT FROM AUTHOR]