Interior Ballistic Process Research Articles

Experimental and Numerical Investigation on Attitude Adjustment Characteristics of Spacecraft with Impulse Thruster

AbstractThe spacecraft serves as an effective tool for the space exploration. The present study is devoted to investigate the yaw attitude adjustment motion of the spacecraft influenced by the reaction-jet control system. A novel spacecraft device with impulse thrusters is designed for the vacuum test. And a synchronous test system, equipped with high-speed cameras, is established to record the motion process of the spacecraft under the various initial setting conditions. Subsequently, a six degrees of the freedom exterior ballistic model is calculated considering the interior ballistic process in the impulse thruster. The experimental results confirm that the position change of the designed device’s center of mass aligns with expectation, and the prediction error of final attitude angle remains below 2%. Based on this foundation, the change rule of the impulse thrust under different main charge loads is explored. The non-linear impulse thrust needs to be coupled with the rotation motion to enhance calculation accuracy. And the position of the center of mass is investigated to illustrate the advantage of the designed spacecraft structure. Finally, the calculation of the ignition interval time required for each target attitude angle is conducted, providing the essential data for further optimization design research. The outcomes from this paper can offer valuable technical means for advancing studies on the spacecraft attitude control.

Simulation of interior ballistic two-phase flow of storage propellant charge

ABSTRACT The launch safety evaluation of artillery considering the properties changes of propellant charge during storage has attracted much attention, and the determination of the interior ballistic process of storage propellant charge has been a bottleneck problem. Large scale firing test is difficult to implement due to its high risk and uncontrollability, and simulation is limited by the difficulty in describing the interaction of propellant parameters. In order to describe the multiple physical fields in the chamber and reveal the influence mechanism of storage on interior ballistic process, the theoretical analysis and physical simulation are combined in this paper. The fracture and the subsequent combustion of the storage propellant charge in the chamber environment were physically simulated, and then, the interior ballistic two-phase flow simulation method considering the fracture of storage propellant charge is proposed by coupling these performance parameters. Though describing the interior ballistic process variation with storage time, this paper provides a practical evaluation method for the interior ballistic performance of energetic materials.

Numerical investigation of the influence of different barrel lengths on the interior ballistic process within an underwater submerged launch

Although underwater submerged launching has been rigorously investigated for decades, there remains a dearth of comprehensive understanding regarding the underwater interior ballistic characteristics for varying barrel lengths. To address this knowledge gap, the present study aims to explore, via numerical simulations, the initial velocity of interior ballistics, projectile drag, and the mechanism of initial flow field formation at the muzzle under various barrel lengths, thereby considering the influence of differing barrel lengths. The five distinct lengths of barrels are expressed as dimensionless ratios of the weight of water column in front of the projectile to the weight of the projectile in order to be more general. Five different ratios of water-to-projectile weight are investigated: 1.0, 1.2, 1.5, 1.8, and 2.0, all possessing identical diameters and evaluated under equivalent launch conditions. Different ratios significantly impact muzzle velocity, with shorter barrels yielding higher muzzle velocities, while ensuring complete propellant combustion. Further investigations indicate that variations in drag constitute the fundamental cause of initial velocity changes. Furthermore, it is observed that barrels of different lengths exhibit identical characteristics at the point of maximum drag. The initial flow field at the muzzle exhibits considerable variations in terms of length, profile dimensions, and intensity. The findings of this study offer valuable insights into exploring the mechanism of submerged launching and will be utilized to investigate the optimal barrel length.

Investigation of heat transfer in cracked gun barrels

Heat transfer process significantly affects the life span of gun barrels as it directly associates to the thermoelastic dynamic responses, erosion, and wears of gun barrels. The previous studies regarding the heat transfer in gun barrels were developed in the realm of local theory that is expressed by partial differential equations with the condition of smoothly distributed physical fields, and have rarely studied the cracked gun barrels. However, on one hand, due to manufacturing errors, there inherently exists fractures in realistic gun barrels; on the other hand, the inner wall of the gun barrel wears due to the high-temperature and -speed burning gas generated during the interior ballistic process, as well as the high-speed friction from projectile’s movement, which severely lead more cracks and damages. Therefore, it is of great importance to investigate the heat transfer in cracked gun barrels. In this paper, a non-local heat transfer model for cracked gun barrels is formulated via the bond-based peridynamics. The governing equation is presented in the manner of integration, such that the heat process with the influence of cracks can be readily captured. Numerical results show that the heat energy severely accumulates on the crack surface and as the size of horizon increases, the non-local characteristics of the heat transfer appear to be more pronounced, resulting in a stiffer thermal response.

Research on the Process of Dispersing the Bullet by a Large-Size Gasbag with Multiple Inlet Nozzles Based on the Fluid–Structure Interaction Method

AbstractTo meet the needs of the airborne dispenser to disperse large-mass bullets, the dispersal system of large-size gasbag with multiple inlet nozzles was designed and built. The rationality and feasibility of the dispersal system were verified by the experimental study of the interior ballistic process. On this basis, the fluid–structure interaction method was used to simulate and analyze the process of the gasbag propelling the bullet when the number of inlet nozzles is different. The calculation results show that the final shape of the expanded gasbag is pillow shaped, and wrinkles appear at the ends of the long side and in the middle of the short side of the gasbag. The stress at the wrinkles is relatively large, and the stress on the wall of the gasbag with three inlet nozzles is greater than that on the wall of the gasbag with two inlet nozzles. Affected by the changes of flow field in the gasbag and the deformation of the gasbag, the process of the gasbag propelling the bullet is divided into two stages, and there are also two large fluctuation peaks during the change of the acceleration of the bullet. Moreover, the expansion process of gasbag with two inlet nozzles lags behind that of the gasbag with three inlet nozzles, and the maximum acceleration and separation velocity of the bullet are also relatively reduced by 2% and 3%, respectively.

An efficient two-phase flow calculation method based on grid mergence and dimension transformation

Two-phase flow numerical methods are applied in internal ballistics widely, which has made higher fidelity analysis with minimal cost become an urgent demand. Current methods are based on independent dimension, and there is no definite conversion criterion and data transmission method, which have limited the application of efficient hybrid models applied to calculation. In this paper, we propose a hybrid method by linking a two dimensional (2D) model to a one dimensional (1D) model for two-phase flow. First, 1D and 2D two-phase flow models are established according to the flow field states in different phases. Next, the criterion of conversion between the two models is established, which is a quantitative index to judge the degree of radial effect and axial effect. Finally, dimension transformation in the radial direction and grid mergence in the axial direction are conducted to complete the whole computing model. The simulation results show that the hybrid method is more efficient in the interior ballistic process and maintains the level of trust in classical codes. Compared with the 2D method, the hybrid method significantly improves the computational efficiency by 86.5%. By analyzing the state in the chamber, the accuracy of the conversion criterion is confirmed. This criterion can be used as the transformation criterion of the hybrid model to form the standard multi-dimensional calculation transformation criterion of interior ballistics and may be promising for the rapid simulation of two-phase flow in interior ballistics.

Launch Dynamic Simulation of a Compressed-Air Launcher for Fire Suppression

This paper focuses on improving fire suppression performance through the use of compressed-air launching technology. A launch dynamics calculation model of a compressed-air launcher is presented, developed using VC++ programming, to simulate the acceleration process of a fire-extinguishing bomb in a barrel. By analyzing the influences of various structural and initial parameters on interior ballistics variations, the effectiveness of the calculation model and program in accurately simulating the launching process is demonstrated. The calculation results indicate that the bore pressure follows a similar trend to that of traditional gunpowder launching. Additionally, it is found that specific structural parameters, such as nozzle diameter and gas cylinder volume, have a direct impact on interior ballistics variations. Notably, the nozzle diameter positively affects the peak pressure, muzzle velocity, gas transfer efficiency, and launch efficiency. To ensure an optimal launch effect and efficiency, the nozzle diameter should be selected to be more than half of the launcher caliber. Similarly, the gas cylinder volume positively influences the peak pressure and muzzle velocity while negatively affecting the gas transfer efficiency and launch efficiency. Furthermore, the initial pressure in the gas cylinder exhibits a positive linear relationship with both the peak pressure and muzzle velocity but a negative linear relationship with the gas transfer efficiency and launch efficiency. The loading position minimally impacts the peak pressure and muzzle velocity but slightly enhances the gas transfer efficiency and launch efficiency. Finally, it is observed that launch angles do not affect the interior ballistic process. The research findings provide valuable theoretical guidance for determining the working parameters of compressed-air accelerated fire-extinguishing bombs.

Research on multiphase flow field characteristics of underwater gun double‐tube parallel firing

AbstractThe underwater muzzle flow field formed by the double‐tube launch will interfere with each other, resulting in large changes in the characteristic parameters of the flow field and shock wave morphology. Therefore, the numerical model of three‐dimensional unsteady multiphase flow for underwater gun‐sealed launching was established. Meanwhile, an experimental platform for the underwater sealed launch was built and the rationality of the model was verified. The interior ballistic process compiled by UDF was coupled with the dynamic mesh technology, and the VOF multiphase flow model integrated with the Schnerr‐Sauer cavitation model was chosen to numerically calculate the muzzle flow field of the 30 mm underwater gun double‐tube parallel launch, and the numerical results were compared to those of the single‐tube launch. The results show that the gas is expelled from the muzzle and rapidly expands to form a gas cavity, and the “necking” phenomenon of the gas cavity occurs at 0.2 ms, while the Mach disk structure has formed. Due to the mutual interference between the flow fields formed by each tube, the diameters of the Mach disk are slightly different, and the flow field structure has a certain asymmetry in the evolution process. The core area of the shock wave is bowl‐shaped of the single‐tube launch, while it is not completely filled of the double‐tube launch. Within 0.5 ms, the diameter of the Mach disk increases monotonously when the single‐tube is launched, while it first increases and then decays by a double‐tube.

The Study of Optimal Design for Interior Ballistics Based on the Reducing Barrel Erosion

Aiming at the problem that the effect of barrel erosion is rarely used as a quantitative constraint in the past interior ballistic design process, the optimization design has been done for a large-caliber gun to improve the barrel life of gun and improve the performance of the interior ballistic, and the equivalent full charges (EFCs) is completed by combining different barrel erosion models with the interior ballistic model. The interior ballistic optimization design simulation represented by the minimization of barrel ablation has realized the optimization of the interior ballistic parameters with the reduction of barrel ablation as the constraint, and obtained the interior ballistic scheme that not only meets the interior ballistic performance indicators, but also helps to reduce the ablation of barrel. The research method formed can guide the design of low-ablation interior ballistic schemes for large-caliber gun, which plays an important role in improving the life of barrel.

Interior ballistic two-phase flow model and its calculation for a mixed charge structure

The mixed charge for guns generally consists of two or more kinds of propellants. Medium and large caliber guns usually adopt the typical combination of tubular and granular propellants, not only meeting interior ballistic indexes but also improving launch safety. However, numerical investigations, charge design, and optimizations of such charge structures rely heavily on classical interior ballistic theory. To gain insight into some crucial phenomena in this complex interior ballistic process, a two-phase flow dynamic model of a 125 mm smoothbore gun with mixed charge (granular propellants, tubular propellants, and a combustible cartridge case) is developed. Unlike the previous form of solid governing equations, the conservation equations, surface temperature and combustion law functions are simultaneously established. The space-time conservation element and solution element (CE/SE) method is used to solve the mathematical model, simplifying the calculations of partial derivatives in source terms. Results show that the model can describe the combustion and flow, and the predicted projectile velocity agrees well with the measured one. In addition, the effects of the mass ratio of mixed propellants on interior ballistic performance are discussed in detail. As the tubular propellant mass decreases, ignition consistency deteriorates, particle accumulation intensifies, and the maximum pressure exceeds the permitted one, all of which may affect launch safety. The work in this paper provides a powerful tool for observing and predicting the interior ballistic process of the mixed charge.

Numerical Method of Propulsion Concept: Partially Cut Multiaperture Stick Propellant

The partially cut Multiaperture stick propellant is a new concept charging structure. In this paper, in order to accurately obtain the change and development process of the two-phase flow field in different stages of the whole interior ballistic process in this propulsion concept system, a coupled calculation model of computational interior ballistic is established, which converts the Euler-Lagrange method to the Euler-Euler method. Firstly, at the initial stage of ignition, the Euler-Lagrange method is used to describe the flow field. During this period, the gas phase is based on Euler coordinates, while the solid phase is based on Lagrangian coordinates. After the projectile starts, the partially cut Multiaperture stick propellant is fractured into granular propellant. The flow field is converted to describe by the Euler-Euler method by using the initial mapping method. Finally, by comparing the calculated results with the experimental results, the maximum pressure error is only 0.54%, which verifies the accuracy and effectiveness of the coupling calculation method. It effectively captures the distribution of the physical parameters in the combustion chamber, providing a new research method for the computational interior ballistic of the propulsion concept. Based on this method, the pressure distribution in the propulsion concept system is obtained, and no obvious shock waves and expansion waves are seen, indicating that the charge scheme of partially cut Multiaperture stick propellant can improve launch safety.

High-Velocity Metal Fragment: Motion Characteristic and Optimization Design

This present work suggests a charge technique to produce a super high-velocity fragment (≥2350 m/s) using a 30 mm launching system. The steel cylindrical fragments with Brinell hardness HB ≤ 270 are designed according to STANAG 4496 in the experiment, and a test system including interval speed measuring device, pressure measurement and high-speed camera is employed to obtain the information on the velocity, pressure and muzzle field of the fragment. The flame characteristics presents an increasing area, and the fragment escapes the control of the muzzle field when the high-velocity fragment is flying out of the muzzle. Moreover, the projectile sabot can timely be separated from the fragment in the range of the first interval velocity measuring device. Based on this, the mathematic models on the interior ballistic process of the fragment movement are established to analyze the effects of various charge structures on the motion characteristic of the fragment. Comparisons of fragment velocity and chamber pressure of computational results are performed with experimental studies. A reasonable match has been obtained in these comparisons. Further, a discussion on the choice of charge parameters is performed by the optimization design for this super high-velocity fragment.

United computational model for predicting thermochemical-mechanical erosion in artillery barrel considering friction behavior

Artillery barrel erosion is mainly divided into two categories, namely thermochemical erosion and mechanical wear. However, most current research on this topic focuses on the former, and lacks sufficient attention to the latter. To describe the coupling relationship of thermochemical-mechanical erosion, this paper is inspired by the friction behavior between barrel and projectile, and proposes a material degradation model of thermochemical erosion considering frictional temperature rise. The change in the friction state caused by the temperature rise in a barrel is characterized by the friction coefficient formula, and updating the interior ballistic movement, results in a novel mechanical friction wear model. Moreover, a mechanical collision wear model is derived using the impact abrasion theory. The followed finite element simulations demonstrate that these proposed quantification models are capable of describing the artillery barrel erosion characteristics during the interior ballistic process more accurately. Good agreement between the numerical simulation and the actual rifling erosion conditions is achieved. The larger erosion is mainly located at the initial part of the rifling and the muzzle, which are about 1.50 mm and 0.45 mm respectively after launching 500 projectiles.

Modeling and Simulation on the Rotating Band Engraving Process of 23 mm Projectile

Dynamic engraving process of 23 mm projectile was studied using numerical simulation. A finite element model of projectile and barrel during the engraving process was constructed, and the deformation process of the driving band, the displacement parameters of the projectile, the force interaction between the projectile and the barrel were determined. To evaluate the simulation model, a semi-static experiment was carried out on an MTS-810 universal testing machine with a cross-head speed of 20 mm min−1. The simulation results show that the mechanism of the 23 mm projectile rotating band engraving process is the plastic deformation process of the rotating band material, engraving time is 1.12 m s, and the projectile velocity after engraving is 105 m s−1. The simulation results reflect the actual rotating band engraving process, which is very distinct from the assumptions used in the classical ballistic model. This work provides an approach to investigating the interior ballistic processes considering the dynamic engraving of rotating bands.

Modeling and Simulation on the Rotating Band Engraving Process of 23 mm Projectile

Dynamic engraving process of 23 mm projectile was studied using numerical simulation. A finite element model of projectile and barrel during the engraving process was constructed, and the deformation process of the driving band, the displacement parameters of the projectile, the force interaction between the projectile and the barrel were determined. To evaluate the simulation model, a semi-static experiment was carried out on an MTS-810 universal testing machine with a cross-head speed of 20 mm min−1. The simulation results show that the mechanism of the 23 mm projectile rotating band engraving process is the plastic deformation process of the rotating band material, engraving time is 1.12 m s, and the projectile velocity after engraving is 105 m s−1. The simulation results reflect the actual rotating band engraving process, which is very distinct from the assumptions used in the classical ballistic model. This work provides an approach to investigating the interior ballistic processes considering the dynamic engraving of rotating bands.

Numerical Simulation and Analysis of Muzzle Flow During a Rarefaction Wave Gun Firing

AbstractRarefaction wave gun can significantly reduce the recoil and the barrel heat without affecting projectile velocity during the launching process. This paper aims to improve the understanding of the muzzle flow characteristics during a rarefaction wave gun firing and clarify the different ballistic behaviors between the rarefaction wave gun and the traditional gun. First, the mathematical models and the numerical methods of the muzzle flow with the interior ballistic process were established. Then, the numerical simulation results were compared with the experimental data to validate the reliability and accuracy. Next, the rarefaction wave propagation behavior was described, and the interior ballistic process of the rarefaction wave gun was compared with that of the traditional gun. Then the development law of the muzzle flow field for the rarefaction wave gun coupled with the interior ballistics process was studied. Finally, the different detailed results of the muzzle flow between the traditional gun and the rarefaction wave gun were investigated. The development processes of the muzzle flow in both guns are generally similar, but the strength of the main flow parameters and the ballistic performances for the rarefaction wave gun are smaller than that for the traditional gun due to the rarefaction wave influence. This paper could provide a valuable reference for the research and design on the rarefaction wave gun.

Improvement of Barrel Weapons Interior Ballistic Model Using Dynamic Vivacity Function

The paper discuses a possibility of application of the dynamic vivacity function defined in COS 137604 (STANAG 4115) at the interior ballistic process mathematical model conversion. At present time various technologies of powder grain surfacing are used mainly in case of powders used in assemblies of small-calibre cartridges. The grain surfacing can properly influence the shot process, change character of the powder grain burning which cannot be described by the burning theory according to geometrical rules. COS 137604 determines necessity of the dynamic vivacity function L evaluation for artillery powders only, but the way of its evaluation can be applied for arbitrary powder. It then allows the get results of the interior ballistic tasks solutions with higher accuracy as well as the choice of the suitable grain surfacing technology.

Proposal of Optimization of Depth Values in Wet Gap Crossing Military Operations

The paper discusses a possibility of application of dynamic vivacity function in interior ballistic process mathematical model. At present time, various technologies of powder grain surfacing are applied, mainly in case of powder grains used in assemblies of small-calibre cartridges. The grain surfacing can desirably influence the interior ballistic action. It can further change basic powder thermodynamic properties, and particularly, it can change the character of the powder grain burning, which cannot be described by geometric burning concept. According to the established standards, a necessity of the dynamic vivacity function L evaluation is determined for artillery powders only, but the way of its evaluation can be applied for arbitrary powder grains. The application of the dynamic vivacity function then allows to get results of solution of the interior ballistic tasks with higher accuracy, as well as the selection of suitable grain surfacing technology.

A calculation method of interior ballistic two-phase flow considering the recoil of gun barrel

The theory of interior ballistic two-phase flow (IBTPF) is the primary means to study the distributions of physical quantities in gun chamber. In previous calculations, the gun breech is usually simplified as a fixed wall boundary, totally ignoring the effect of gun barrel recoil on interior ballistic processes. Thus to truly describe the interior ballistic process of the self-propelled gun (SPG), the transfer matrix method of multibody system (MSTMM) is combined with the theory of IBTPF in this paper. By simultaneously solving the generalized coordinate equations of multibody system and the conservation equations of IBTPF, the gun barrel recoil is converted to the moving boundary of the gun breech, and a more accurate calculation method of IBTPF is established. The results show that the simulated vibration characteristics, dynamic response during launch as well as interior ballistic performance of the SPG are all in good agreement with test values. Compared with no recoil, the gun barrel motion affects the growth regularity of the chamber volume behind the projectile, and eventually results in the changes of interior ballistic performance indexes such as maximum breech pressure and muzzle velocity. Overall, this study provides a more accurate prediction and simulation tool to enable better insight into such complicated interior ballistic processes, which is of great significance to the launch safety analysis and subsequent ballistic calculations.

Interior Ballistics of Amphibious Rifle when Firing under Water

The paper deals with an adaptation of the standard interior ballistics model for the case of amphibious rifle shooting ammunition under water. The adapted mathematical model was validated and experimentally verified using the 5.56 mm underwater projectile shot from the 5.56 mm amphibious rifle. The dependence of the underwater interior ballistic processes on the powder mass was investigated. The results of theoretical mathematic model solution correspond very well with experiment. The described mathematical model and the dependence of the underwater interior ballistic processes on the powder mass can be a reference for designers in the design process of the underwater ammunition or underwater rifle.