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1.
Jin-Sung Jang Hyung-Gun Sung Tae-Seong Roh Dong-Whan Choi 《Journal of Mechanical Science and Technology》2013,27(8):2351-2357
A numerical code for interior ballistics using the Eulerian-Lagrangian approach was developed to analyze polydisperse systems. The internal flows in a gun barrel and the compressibility effects were calculated using the semi-implicit method for pressure-linked equations algorithm. Ghost cell extrapolation was used for the moving boundary with projectile movement. The numerical scheme and moving boundary method were verified through the free piston motion problem. The developed code, including the combustion of the propellant, was compared with simulations of 40 mm gun firings. The results of numerical analysis agree with the simulation results, confirming the reliability of the developed code. Comparative studies were conducted with the results of the interior Ballistics of high-velocity guns code (version 2) according to porosity and propellant size. The numerical analysis of the combustion and movement of individual propellants provides deeper insight into the mechanism of gun firing and the significant factors that influence muzzle velocity. 相似文献
2.
火炮极限射击条件用于考核火炮在最严酷射击条件下的工作情况,传统火炮极限射击条件是在对影响参量定性分析基础上,依据经验大致确定的。为准确确定某火炮的极限射击条件,将内弹道模型和火炮反后坐装置模型结合起来,建立了系统的火炮射击数值仿真模型,在仿真的基础上,首先分析了相关参量对射击条件的影响;而后用人工神经网络拟合仿真计算以减少仿真时间、用模拟退火和基因算法等优化算法对射击条件进行优化,得到了极限射击条件;最后,计算了极限射击条件位置各影响参量的灵敏度。 相似文献
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采用计算流体力学方法结合动网格技术建立了双管火炮异步发射时膛口流场的二维数值模拟模型,正确描述了双管不同步发射时炮口流场的激波系结构的形成﹑发展与相互干扰的过程。模拟结果得出双管不同步发射时对弹丸飞出膛口后的飞行姿态影响较大,从而弹丸偏移速度会影响双管火炮的射击精度。 相似文献
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为了研究某高低压榴弹发射器的内弹道规律,根据高低压发射原理和气固两相流的相关理论,建立了近似枪膛装置中高低压室的两相流内弹道方程组,采用MacCormack差分格式进行了数值计算.计算结果与实验结果对比分析,模型和算法是可行的.通过调整某一参数,应用所得算法程序,可以实现某榴弹发射器改变内弹道性能的要求,或者预测预研榴弹武器的性能. 相似文献
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身管是火炮武器的重要部件,身管制造材料和加工工艺直接影响身管的质量。身管质量严重影响身管寿命,低质身管会导致火炮内弹道性能降低,射击精度下降,制约着武器效能的发挥。深入研究身管问题,分析了身管使用材料发展历程,归纳总结出身管的典型加工工艺,为身管的设计和使用提供参考。 相似文献
7.
Flow instability in LRE (liquid rocket engine) occurs due to various reasons such as flow interactions with valve, orifice
and venturi, etc. The inception of cavitation, especially in the propellant feeding system, is the primary cause of mass and
pressure oscillations because of the cyclic formation and depletion of cavitation. Meanwhile, the main propellant in a liquid
rocket engine is the cryogenic fluid, which properties are very sensitive to temperature variation. And the change of propellant
properties to temperature variation by thermodynamic effect needs to be properly taken into account in the flow analysis in
order to understand basic mechanisms for cryogenic cavitation. The present study focuses on the formation of cryogenic cavitation
by using the IDM model suggested by Shyy and coworkers. The flow instability was also numerically investigated in the downstream
of orifice with a developed numerical code. Calculation results show that cryogenic cavitation can be a primary source of
flow instability, leading to mass fluctuations accompanied by pressure oscillations. The prediction of cavitation in cryogenic
fluid is of vital importance in designing a feeding system of an LRE.
This paper was recommended for publication in revised form by Associate Editor Jun Sang Park
Changjin Lee received his B.S. and M.S. degrees in Aeronautical Engineering from Seoul National University in 1983 and 1985. He then went
on to receive his Ph.D. degree from University of Illinois at Urbana- Champaign in 1992. Dr. Lee is currently a Professor
at the department of Aerospace Engineering at Konkuk University in SEOUL, Korea. His research interests are in the area of
combustion instabilities of hybrid, liquid rocket and jet propulsions.
Tae-Seong Roh received his B.S. and M.S. degrees in Aeronautical Engineering from Seoul National University in 1984 and 1986. He then went
on to receive his Ph.D. degree from Pennsylvania State University in 1995. Dr. Roh is currently a Professor at the department
of Aerospace Engineering at Inha University in Incheon, Korea. His research interests are in the area of combustion instabilities,
rocket and jet propulsions, interior ballistics, and gas turbine engine defect diagnostics. 相似文献
8.
Hafizur Rehman Seung Hwa Hwang Berkah Fajar Hanshik Chung Hyomin Jeong 《Journal of Mechanical Science and Technology》2011,25(10):2601-2606
Due to the supersonic speed at which propellant gas flows through the gun barrel, a high intensity impulsive sound pressure
is created, which has negative effects in many respects. Therefore, the high pressure waves generated due to muzzle blast
flow of tank gun during firing is a critical issue to examine. The purpose of this paper is to study and analyze this high
pressure impulsive sound, generated during the blast flow. The large caliber 120 mm K1A1 tank gun has been selected especially
for this purpose. An axisymmetric computational domain has been constructed by employing Spalart Allmaras turbulence model
to evaluate pressure and sound level in the tank gun using Computation Fluid Dynamics technique. Approximately 90% of pressure
and 20 dB of sound level have been attenuated due to use of the three baffle silencer at the muzzle end of the gun barrel
in comparison to the tank gun without silencer. Also, the sound pressure level at different points in the ambient region shows
the same attenuation in the results. This study will be helpful to understand the blast wave characteristics and also to get
a good idea to design silencer for large caliber weapon system. 相似文献
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在半开腔膛口制退器基础上进行改进,提出喷管高效膛口制退器的概念,在半开腔膛口制退器两侧引出可水平向后的拉瓦尔喷管,利用火药燃气通过喷管气流的反推作用达到减后坐效果,通过编程进行内弹道计算。运用刚柔耦合动力学理论,对安装喷管高效膛口制退器车载转管机枪系统建立动力学模型,进行动力学仿真计算。计算结果表明,安装喷管高效膛口制退器后,机枪后坐力、后坐位移、膛口角位移和弹丸出膛口时角位移均得到减小,提高了机枪的射击性能。 相似文献
11.
Many researchers have investigated the blood flow characteristics through bileaflet mechanical heart valves using computational
fluid dynamics (CFD) models. Their numerical approach methods can be classified into three types; steady flow analysis, pulsatile
flow analysis with fixed leaflets, and pulsatile flow analysis with moving leaflets. The first and second methods have been
generally employed for two-dimensional and three-dimensional calculations. The pulsatile flow analysis interacted with moving
leaflets has been recently introduced and tried only in two-dimensional analysis because this approach method has difficulty
in considering simultaneously two physics of blood flow and leaflet behavior interacted with blood flow. In this publication,
numerical calculation for pulsatile flow with moving leaflets using a fluid-structure interaction method has been performed
in a three-dimensional geometry. Also, pulsatile flow with fixed leaflets has been analyzed for comparison with the case with
moving leaflets. The calculated results using the fluid-structure interaction model have shown good agreements with results
visualized by previous experiments. In peak systole, calculations with the two approach methods have predicted similar flow
fields. However, the model with fixed leaflets has not been able to predict the flow fields during opening and closing phases.
Therefore, the model with moving leaflets is rigorously required for advanced analysis of flow fields. 相似文献
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In current research on deflector jet servo valves, the receiver pressure estimated using traditional two-dimensional simulation and theoretical calculation is always lower than the experimental data; therefore, credible information about the flow field in the prestage part of the valve can hardly be obtained. To investigate this issue and understand the internal characteristics of the deflector jet valve, a realistic numerical model is constructed and a three-dimensional simulation carried out that displays a complex flow pattern in the deflector jet structure. Then six phases of the flow pattern are presented, and the defects of the two-dimensional simulation are revealed. Based on the simulation results, it is found that the jet in the deflector has a longer core area and the fluid near the shunt wedge cannot resist the impact of the high-speed fluid. Therefore, two assumptions about the flow distribution are presented by which to construct a more complete theoretical model. The receiver pressure and prestage pressure gain are significantly enhanced in the calculations. Finally, special experiments on the prestage of the servo valve are performed, and the pressure performance of the numerical simulation and the theoretical calculation agree well with the experimental data. Finally, the internal mechanism described by the theoretical and numerical models is verified. From this research,more accurate numerical and theoretical models are proposed by which to figure out the internal characteristics of the deflector jet valve. 相似文献
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以美国麻省理工学院(MIT)研制的硅基六晶片微燃烧室为研究对象,提出利用二维CFD(计算流体动力学)数值模拟的方法,研究在保持微尺度燃烧室进口氢气/空气流量不变的情况下,改变氢气/空气当量比对燃烧室燃烧特性的影响。整个模拟计算主要包括氢气/空气的流动路径、微燃烧室的内部区域以及整个燃烧室的墙壁面;同时在计算过程中我们考虑了氢气/空气的流体动力学特性、传热学特性和详细的基元反应机理。结果表明,利用二维CFD数值模拟的方法研究微尺度燃烧室燃烧特性可行,与国外实际测量结果较为相似,为今后微型燃气轮机燃烧室的研制及改进提供了一定的参考依据。 相似文献
17.
Kuk-Jeong Kang Sung-Ho Ko Dong-Soo Lee 《Journal of Mechanical Science and Technology》2008,22(1):190-200
The present work addresses a numerical study on impulsive sound attenuation for a complex high-pressure blast flowfield; these
characteristics are generated by a supersonic propellant gas flow through a shock tube into an ambient environment. A numerical
solver for analyzing the high pressure blast flowfield is developed in this study. From numerical simulations, wave dynamic
processes (which include a first precursor shock wave, a second main propellant shock wave, and interactions in the muzzle
blasts) are simulated and discussed. The pressure variation of the blast flowfield is analyzed to evaluate the effect of a
silencer. A live firing test is also performed to evaluate four different silencers. The results of this study will be helpful
in understanding blast wave and in designing silencers. 相似文献
18.
Numerical and experimental studies on the dynamic behaviors of a gun that uses the soft recoil system 总被引:1,自引:0,他引:1
The conventional recoil mechanism of guns provides the retarding force on the gun to stop the rearward motion in the firing cycle. The concept of the soft recoil mechanism has been developed. This mechanism was introduced to reduce the firing shock and the reaction force due to the forward momentum of the recoiling parts prior to firing. This paper verifies the theory of the soft recoil mechanism and demonstrates its feasibility on a large-caliber gun system. Numerical simulation on recoil dynamics and shock response analysis were utilized in this study. A FORTRAN program, which was developed in a previous study, was employed for simulation. The shock response analysis utilized the shock response spectrum and the pseudo-velocity shock spectrum. As a result, a newly developed recoil system was proven to be applicable for guns in the near future with further refinements. 相似文献
19.
Based on an underwater gun firing project, a mock bullet with several holes on the head was designed and experimented to observe the combustion gas injected into a cylindrical water chamber through this mock bullet. The combustion gas jets contain one vertical central jet and 4 to 8 slant lateral jets. A high speed camera system was used to record the expansion of gas jets in the experimental study. In numerical simulations, the Euler two-fluid model and volume of fluid method were adopted to describe the gas-liquid flow. The results show the backflow zone in lateral jet is the main factor influencing the gas-liquid turbulent mixing in downstream. On cross sections, the gas volume fraction increased with time but the growth rate decreased. With a change of nozzle structure, the gas fraction was more affected than the shock structure. 相似文献