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An internal ballistic model of electromagnetic railgun based on PFN coupled with multi-physical field and experimental validation

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Defence technology（防务技术） 2024年第2期32卷 254-261页

作者： Benfeng Gu Haiyuan Li Baoming Li National Key Laboratory of Transient Physics Nanjing University of Science and TechnologyNanjing 210094China

To accelerate the practicality of electromagnetic railguns,it is necessary to use a combination of threedimensional numerical simulation and experiments to study the mechanism of bore *** this paper,a three-dimensional numerical model of the augmented railgun with four parallel unconventional rails is introduced to simulate the internal ballistic process and realize the multi-physics field coupling calculation of the rail gun,and a test experiment of a medium-caliber electromagnetic launcher powered by pulse formation network(PFN)is carried *** test methods such as spectrometer,fiber grating and high-speed camera are used to test several parameters such as muzzle initial velocity,transient magnetic field strength and stress-strain of *** the simulation results and experimental data,the damage condition of the contact surface is analyzed.

关键词： Internal ballistic modeling Electromagnetic rail gun Multi-physics field coupling Experimental validation PFN

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Study, development and related application of a miniature compact pulsed power supply with high repetition frequency

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Defence technology 2025年 47卷 304-318页

作者： Wang, Zhangfei Liu, Jian Yang, Chunxia Li, Baoming National Key Laboratory of Transient Physics Nanjing University of Science and Technology Nanjing210094 China

Capacitor-based pulsed power supply (PPS) is widely used in fields related to electromagnetic launch, plasma, and materials' synthesis, modification and processing. As industrial applications place higher requirements on compact and portable pulsed power supplies, the National Key laboratory of transient physics (NKLTP) recently developed a pulsed power supply consisting of a set of compact pulse-forming units (PFU), each with a capacitor energy storage of 220 kJ. This integrated PPS comes with a complete system configuration, a miniature compact structure, a high rate of repetition, and high power, with energy storage density exceeding 1.2 MJ/m3. This paper describes the device-level design of the unit, the system layout, the control system, the thermal management system, and the experimental results of the pulsed power supply. The experimental results verified the good reliability of the PPS at high repetition rates with each unit module delivering an output current of more than 100 kA. Additionally, flexible current pulse shapes can be formed by setting the charging voltage and the trigger sequence of the PFUs. The pulse forming network (PFN) developed from these PFUs was successfully applied to electromagnetic launch. © 2025 China Ordnance Society

关键词： Rail guns

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Study on the formation characteristics of underwater hemispherical shaped charge jet and its penetration performance into concrete

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Defence technology 2025年 47卷 180-196页

作者： Cao, Chao Wang, Jinxiang Kong, Lingquan Tang, Kui Xiao, Yujie Gu, Yangchen Yang, Ming Wang, Jian National Key Laboratory of Transient Physics Nanjing University of Science and Technology Nanjing210094 China Naval Research Institute Beijing100841 China

Shaped charge has been widely used for penetrating concrete. However, due to the obvious difference between the propagation of shock waves and explosion products in water and air, the theory governing the formation of shaped charge jets in water as well as the underwater penetration effect of concrete need to be studied. In this paper, we introduced a modified forming theory of an underwater hemispherical shaped charge, and investigated the behavior of jet formation and concrete penetration in both air and water experimentally and numerically. The results show that the modified jet forming theory predicts the jet velocity of the hemispherical liner with an error of less than 10%. The underwater jets exhibit at least 3% faster and 11% longer than those in air. Concrete shows different failure modes after penetration in air and water. The depth of penetration deepens at least 18.75% after underwater penetration, accompanied by deeper crater with 65% smaller radius. Moreover, cracks throughout the entire target are formed, whereas cracks exist only near the penetration hole in air. This comprehensive study provides guidance for optimizing the structure of shaped charge and improves the understanding of the permeability effect of concrete in water. © 2024 China Ordnance Society

关键词： Cracks

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Experimental study of the influence of annular nozzle on acoustic characteristics of detonation sound wave generated by pulse detonation engine

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Chinese physics B 2022年第10期31卷 436-443页

作者： Yang Kang Ning Li Xiao-Long Huang Chun-Sheng Weng National Key Laboratory of Transient Physics Nanjing University of Science and TechnologyNanjing 210094China

Acoustic characteristics of the detonation sound wave generated by a pulse detonation engine with an annular nozzle,including peak sound pressure, directivity, and A duration, are experimentally investigated while utilizing gasoline as fuel and oxygen-enriched air as oxidizer. Three annular nozzle geometries are evaluated by varying the ratio of inner cone diameter to detonation tube exit diameter from 0.36 to 0.68. The experimental results show that the annular nozzles have a significant effect on the acoustic characteristics of the detonation sound wave. The annular nozzles can amplify the peak sound pressure of the detonation sound wave at 90° while reducing it at 0° and 30°. The directivity angle of the detonation sound wave is changed by annular nozzles from 30° to 90°. The A duration of the detonation sound wave at 90° is also increased by the annular nozzles. These changes indicate that the annular nozzles have an important influence on the acoustic energy distribution of the detonation sound wave, which amplify the acoustic energy in a direction perpendicular to the tube axis and weaken it along the direction of the tube axis.

关键词： pulse detonation engine annular nozzle detonation sound wave acoustic characteristics

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Experimental study on propagation characteristics of rotating detonation wave with kerosene fuel-rich gas

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Defence technology（防务技术） 2022年第8期18卷 1498-1512页

作者： Jia-xiang Han Qiao-dong Bai Shi-jian Zhang Fang Wang Chun-sheng Weng National Key Laboratory of Transient Physics Nanjing University of Science and TechnologyNanjing210094China

In this study, kerosene fuel-rich gas produced by the combustion in the gas generator was used as the fuel and oxygen-rich air was used as the oxidant to investigate the propagation characteristics of the rotating detonation wave (RDW). The initiation of the kerosene fuel-rich gas and propagation process of the RDW were analyzed. The influences of the oxygen content in the oxidizer, kerosene mass flow rate of the gas generator, and temperature of the kerosene fuel-rich gas on the propagation process of the RDW were studied. The experimental results revealed that the propagation velocity of the RDW could be improved by increasing the three parameters mentioned above with the kerosene mass flow rate as the strongest factor. The minimum oxygen content that could successfully initiate and maintain the stable propagation of the RDW was 32%, achieving the RDW velocity of 1141.9 m/s. The RDW mainly propagated as two-counter rotating waves and a single wave when the equivalent ratios were 0.62–0.79 and 0.85–0.87, respectively. The highest RDW velocity of 1637.2 m/s was obtained when the kerosene mass flow rate, oxygen content, and equivalent ratio were 74.6 g/s, 44%, and 0.87, respectively.

关键词： Rotating detonation wave Kerosene fuel-rich gas Initiation process Propagation mode

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In situ measurement on nonuniform velocity distributionin external detonation exhaust flow by analysis ofspectrum features using TDLAS

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Chinese physics B 2022年第1期31卷 417-427页

作者： Xiao-Long Huang Ning Li Chun-Sheng Weng Yang Kang National Key Laboratory of Transient Physics Nanjing University of Science and TechnologyNanjing 210094China

Instantaneous and precise velocity sensing is a critical part of research on detonation mechanism and flow *** paper presents a novel multi-projection tunable diode laser absorption spectroscopy solution,to provide a real-time and reliable measurement of velocity distribution in detonation exhaust flow with obvious *** are established between overlapped spectrums along probing beams and Gauss velocity distribution phantom according to the frequency shifts and tiny variations in components of light-of-sight absorbance profiles at low frequencies analyzed by the fast Fourier *** simulated optical measurement using H2O feature at 7185.6 cm-1 carried out on a phantom generated using a simulation of two-phase detonation by a two-fluid model,this method demonstrates a satisfying performance on recovery of velocity distribution profiles in supersonic flow even with a noise equivalent absorbance up to 2×10^(-3).This method is applied to the analysis of rapidly decreasing velocity during a complete working cycle in the external flow field of an air-gasoline detonation tube operating at 25 Hz,and results show the velocity in the core flow field would be much larger than the arithmetic average from traditional tunable diode laser doppler *** proposed velocity distribution sensor would reconstruct nonuniform velocity distribution of high-speed flow in low cost and simple operations,which broadens the possibility for applications in research on the formation and propagation of external flow filed of detonation tube.

关键词： velocity distribution tunable diode laser absorption spectroscopy nonuniform flow Doppler effect

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Numerical simulation of flow field characteristics and the improvement of pressure oscillation of rotating detonation engine

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Defence technology（防务技术） 2023年第8期26卷 191-202页

作者： Xin-pei Han Quan Zheng Bao-xing Li Qiang Xiao Han Xu Fang Wang Hao-long Meng Wen-kang Feng Chun-sheng Weng National Key Laboratory of Transient Physics Nanjing University of Science and TechnologyNanjing210094China Xi'an Modern Chemistry Research Institute Xi'an710065China

Due to the inherent working mode of rotating detonation engine(RDE),the detonation flow field has the characteristics of pressure oscillation and axial kinetic energy loss,which makes it difficult to design nozzle and improve propulsion ***,in order to improve the characteristics of detonation flow field,the three-dimensional numerical simulation of annular chamber and hollow chamber is carried out with premixed hydrogen/air as fuel in this paper,and then tries to combine the two chambers to weaken the oscillation characteristics of detonation flow field through the interaction of detonation flow field,which is a new method to regulate the detonation flow *** results show that there are four states of velocity vectors at the outlet of annular chamber and hollow chamber,which makes RDE be affected by rolling moment and results in the loss of axial kinetic *** the external flow field of combined chamber,the phenomenon of cyclic reflection of expansion wave and compression wave on the free boundary is observed,which results in Mach disk ***,the pressure monitoring points are set at the external flow *** pressure signal shows that the high-frequency pressure oscillation at the external flow field of the combined chamber has been greatly *** to the annular chamber,the relative standard deviation(RSD) has been reduced from 14.6% to5.6%.The results thus demonstrate that this method is feasible to adjust the pressure oscillation characteristics of the detonation flow field,and is of great significance to promote the potential of RDE and nozzle design.

关键词： Detonation flow field Combined chamber Pressure oscillation Velocity vector

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A prediction approach for partial properties of filament wound composite tube considering fiber winding prestressing 4

A prediction approach for partial properties of filament wou...

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4th International Conference on Defence technology, ICDT 2024

作者： Yin, Dongmei National Key Laboratory of Transient Physics Nanjing University of Science and Technology Nanjing China

The initial residual prestress in the filament-wound products would affect their mechanical properties. Based on the multi-scale homogenization principle, this work proposes a method to predict the equivalent elastic properties of the filament-wound composites which can consider fiber winding prestressing. Combining with the quasi three-dimensional laminated plates theory, the bridging model with considering the thermal stress is adopted in this prediction model. Through this model, the effects of the fiber pre-tension and curing cooling temperature on the equivalent axial elastic modulus of the filament wound glass fiber/epoxy tubes are analyzed. In additions, the equivalent outer diameters of these tubes are also forecasted. Most of the results obtained by this theoretical model are close to the experimental results in the reference. It indicates that this model is reliable to some extent, and it can provide a reference for the design of properties of the filament wound composite tube. © 2024 Institute of physics Publishing. All rights reserved.

关键词： Glass fibers

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Study on chemical kinetics of plasma-assisted energetic material combustion 4

Study on chemical kinetics of plasma-assisted energetic mate...

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4th International Conference on Defence technology, ICDT 2024

作者： Guo, J.T. Yang, C.X. National Key Laboratory of Transient Physics Nanjing University of Science and Technology Nanjing210094 China

The combustion kinetic mechanism of C4H8N8O8(HMX) is established, with 30 components and 94 reactions. To account for the effects of plasma ignition and assisted combustion, the model incorporates reactions involving H free radicals at varying mole fractions. The thermodynamic parameters of products and combustion pathways of HMX are analysed by using Chemkin. The result of sensitivity analysis shows that the reaction of N2O+H=OH+N2has a great influence on the ignition delay time. H and OH radicals play a positive role in ignition, while OH has higher activity than H. The sensitivity analysis of OH shows that N2O+H=OH+N2has high sensitivity and highest reaction rate. As the mole fraction of H in the reaction chamber increases, the generation rate of OH increases. The reaction rate at 0.2 mole concentration of H is twice higher than 0.1 mole concentration. The increase of OH mole fraction increases the reactivity and decreases the ignition delay time. © 2024 Institute of physics Publishing. All rights reserved.

关键词： Sensitivity analysis

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Design of Control Strategies for Electric Actuators in 155mm 4

Design of Control Strategies for Electric Actuators in 155mm

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4th International Conference on Defence technology, ICDT 2024

作者： Cai, Xiu Guan, Xueyuan Zhang, Chen Wang, Yanyi National Key Laboratory of Transient Physics Nanjing University of Science and Technology Nanjing210094 China

The performance of electromagnetic servo actuators as the control execution mechanism for guided projectiles plays a crucial role in the control system of guided projectiles. Due to the limited internal space of correction projectiles and the need to adapt to high-speed rotation, high overload, and small volume environments, the structure, control, and drive circuits of the electromagnetic servo actuators should be miniaturized as much as possible while meeting the requirements and control accuracy. This paper introduces the principle design of the motor drive and control circuit. A permanent magnet synchronous motor is adopted according to the characteristics of the required electromagnetic servo actuators. The model of the permanent magnet synchronous motor is studied, and based on the extended Kalman filter state observer, the estimation of the motor rotor position and speed is conducted. Subsequently, closed-loop vector control simulations of current, speed, and position are performed using Matlab/Simulink to evaluate the control strategy's effectiveness in actual 155mm correction projectile payloads. This research can provide beneficial reference and guidance for the optimization of electromagnetic servo actuators in practical applications. © 2024 Institute of physics Publishing. All rights reserved.

关键词： Permanent magnets

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