Table of Content

01 May 2012, Volume 33 Issue 5

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Paper

Two Phase Flow Numerical Simulation of Interior Ballistics of the Series Chamber Gun

LI Hai-qing， ZHANG Xiao-bing， WANG Yan

2012, 33(5):  513-518.  doi:10.3969/j.issn.1000-1093.2012.05.001

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Series chamber is a new technology on the basis of the mature technology of solid propellant. It can improve the propeller’s kinetic energy through rebuilding the existed guns. It is important to the weapons’ performance improvement. The two phase flow model of the interior ballistics process of 140 mm series chamber gun is established and simulated by MacCormack scheme. In addition, the completed programming has been used to analyze the influence of main-secondary powder proportion，ignition delay of secondary power and piston mass on interior ballistics performance. The result shows that the new technology can improve propeller’s velocity while not adding chamber’s pressure.

Experimental Study and Numerical Simulation on Property of Pulsed Plasma Jet-LiquidInteraction

ZHANG Qi， YU Yong-gang， LIU Dong-yao， LU Xin

2012, 33(5):  518-524.  doi:10.3969/j.issn.1000-1093.2012.05.002

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In order to understand the plasma jet-liquid media interaction characteristics, a high speed digital camera system was used to record the propagation process of plasma jet in liquid media in cylindrical chamber. The properties of the axial and radial displacements of plasma jet in liquid media and the change in its spread speed with time were obtained. Based on experiment, a two-dimensional-axisymmetric, unsteady mathematical model was developed. Numerical simulation of this process was carried out. The temporal and spatial distributions of volume fractions of plasma and liquid were obtained. The axial displacement calculated from the numerical simulation matches well with that from experiment. The distributions of pressure, velocity and temperature of the flow filed were obtained, and the discontinuous mechanism of Taylor cavity was analyzed.

Research on the Angle Tracking Pointing Performance of 3D Dynamic Acoustic Array Based onDual Acoustic Sources

LIU Ya-lei， GU Xiao-hui

2012, 33(5):  526-533.  doi:10.3969/j.issn.1000-1093.2012.05.003

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In order to study the angle tracking problem of 3D dynamic acoustic array for two-dimensional acoustic target under the interference of point acoustic source, the basic principle of multi-source interference was analyzed, and a mathematical model of angle tracking pointing performance of dynamic acoustic array under the interference of dual acoustic sources was established. The angle tracking pointing performance of dynamic acoustic array under the interference of point acoustic source was analyzed based on the acoustic signal characteristic difference between Pseudo target and real target, so the relationship between its angle tracking pointing performance and the interference factors were obtained. Finally, the evaluation indicator of angle tracking pointing performance under the interference of point acoustic source also was established based on the hypothesis of equal power under the interference of dual acoustic sources .

Research on Preparation of Microfoam Oblate Spherical Propellants by Supercritical CO₂

CHEN Xi-ru, YING San-jiu, XIAO Zheng-gang

2012, 33(5):  534-539.  doi:10.3969/j.issn.1000-1093.2012.05.004

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The microfoam oblate spherical propellants were designed and prepared in temperature-rising progress by supercritical fluids technique in order to improve their burning performance based on progressive burning surfaces theory and the mechanisms of foam nucleation and growth in the foaming progress were discussed. The effects of the contents of CO₂ and particles on foam morphology were investigated. Scanning electron microscope(SEM) results showed that foams in microfoam oblate spherical propellants were closed and isolated, foam morphology can be changed by particle and the mean foam diameter became small as the contents of CO₂ in oblate spherical propellants decreasing. The closed bomb tests indicated that these microfoam oblate spherical propellants showed progressive burning performance. Therefore the microfoam oblate spherical propellants with different foam morphology and burning performance can be achieved by supercritical fluids technique.

Experimental Research for Cavity and Ballistics of a Rotating Bullet EntrainingWater Levelly

GU Jian-nong, ZHANG Zhi-hong, WANG Chong， FAN Wu-jie

2012, 33(5):  540-544.  doi:10.3969/j.issn.1000-1093.2012.05.005

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The hydro-ballistic trajectory and cavity of the half sphere bullet and general pistol bullet are experimentally researched by a high speed digital video recorder when they entrain water at six speeds and at two depths of water. The experimental results show that the shape of a bullet has important influence upon the hydro-ballistics stability of the bullet motion. The hydro-ballistics of the half sphere bullet is stability, but the stability is not well for pistol bullet. The shape of pistol bullet cavity is “lotus root”. The velocity attenuation law of the bullet have similarity at a range of bullet entraining water speeds. The velocity attenuation law in water has similarity for both of the half sphere and pistol bullet. The speed of bullet in water decreases very quickly. A calculation model is established to predict the velocity attenuation law of the bullet. The calculation results are compared with the experimental results, they agree well with each other.

Exterior Ballistic Discrimination Method of a Mortar Bomb Based on Turbine Alternator Output

GAO Min₁, JING Ya-xing₁, LIU Qiu-sheng₂, LU Jing₂

2012, 33(5):  545-551.  doi:10.3969/j.issn.1000-1093.2012.05.006

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Based on turbine alternator as a velocity sensor to discriminate trajectory, a new feasible trajectory discrimination method was put forward. Output frequency characteristics of turbine alternators and variable function of trajectory velocity were analyzed, considering various state of turbine alternator rotation. systematic scheme of trajectory discrimination was set up by use of turbine alternator outputs, and realization process of trajectory discrimination was depicted detailed. Moreover, establishment process of basic functions for trajectory discrimination was discussed by instance simulation. The simulation result indicates that calculation workload and error of trajectory discrimination are small and acceptable, therefore, with the addition of turbine alternator application on fuzes, the new trajectory discrimination method is feasible.

Study on Dimension Effect of Accelerating Ability and JWL Equation of State for Aluminized Explosive

JI Dong-kui, GAO Xiu-zhu, XIAO Chuan, WU Yong-zhong, YANG Kai

2012, 33(5):  552-555.  doi:10.3969/j.issn.1000-1093.2012.05.007

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The results of two sets of cylinder test for aluminized explosive to study the dimension effect of accelerating ability and Jones-Wilkins-Lee (JWL) equation of state for aluminized explosive were reported, with diameter of 25 mm and 50 mm, respectively. By using theory analysis and 2D numerical simulations for the cylinder test, the parameters of JWL equation of state for aluminized explosive were determined. The result indicates that the big aluminized explosive charge has higher ability of accelerating than that of the small one, and its parameters of JWL equation of state are different from small ones.

Experimental Study and Initial Velocity Calculation of Particles Dispersed by Center Explosive

CHEN Ya-hong, BAI Chun-hua, LIU Yi, LI Jian-ping, WANG Zhong-qi

2012, 33(5):  556-559.  doi:10.3969/j.issn.1000-1093.2012.05.008

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There are some differences in dynamic mechanics between metal particle pack and metal fragments driven by explosive, and the velocity metal particles obtained differs from calculation of Gurney model, that imply the Gurney model can not be directly used to calculate the velocity of metal granular swarm driven by explosive. Metal granular swarm dispersed by cylinder explosive was investigated experimentally, and the result shows that the average initial velocity of particles is less than that calculated with Gurney model. Besides the mass ratio between granular swarm and explosive, other 4 factors including lateral effect, porosity, particle size, and true density of particle also affect average initial velocity of particles. Considering the 4 factors, Gurney model was modified to calculate average initial velocity of particles dispersed by explosive, and the result was in good agreement with experiment. The modified Gurney model can be used to the engineering calculations of average initial velocity of explosive dispersing metal granular.

Synthesis and Property of Energetic Dinitromethanide Salts and Their Thermal DecompositionReaction Kinetics

CAO Dan， SONG Jin-hong， HUANG Hai-feng， LIANG Li-xuan，

2012, 33(5):  560-565.  doi:10.3969/j.issn.1000-1093.2012.05.009

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3,4,5-triamino-1,2,4-triazolium and N-carbbamoylguanidinium dinitromethanide salts were synthesized and characterized by using N-guanylurea hydrochloride and 3,4,5-triamido-1,2,4-triazole as starting materials. The Gaussian 03 program was used to calculate the enthalpies of formation of the newly synthesized salts based on actually measured density, the calculated detonation velocities were 8 933 m/s and 8 035 m/s, and the detonation pressures were 36.6 GPa and 28.4 GPa. the results show that the explosion properties of the salts are comparable to RDX. Their thermal behaviors and non-isothermal decomposition reaction kinetics were investigated by thermogravimetry and derivative thermogravimetry (TG-DTG). The calculated ΔS, ΔH and ΔG≠ were 3.60 J/（mol·K）, 125.54 kJ/mol and 123.96 kJ/mol, respectively.

Research on Numerical Simulation Method of Near-field Flows in Air Blast

XU Chun-guang， BAI Xiao-zheng ， LIU Yu ， LIU Jun

2012, 33(5):  566-573.  doi:10.3969/j.issn.1000-1093.2012.05.010

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A new method of simulating the explosion flowfield due to the interaction of explosives, detonation products and air was proposed. A mixing model of explosives, detonation products and air was introduced in Eulerian method. In this model, Jones-Wilkins-Lee(JWL) state equation was used for the explosives and products, while a prefect gas state equation was used for air; an equilibrium pressure assumption was made between explosives and products, while an equilibrium temperature assumption was made between products and air; no iteration is required in this model, so a high efficiency is achieved. An ignition and growth model was used to calculate the chemical reactivity, and AUSM₊-up scheme was used to calculate the convection flux. The explosion of spherical TNT explosives in air was calculated, and a series of complex interactions, such as transmission and reflection, between detonation wave and fluid interface were observed. The calculated peak over-pressure accords well with experimental results even at 5 cm from the explosive surface. The arriving time of blast wave and the specific impulse of overpressure also accord well with the existing experimental results, which validates the availability and accuracy of the method.

Measurement and Analysis of Shock Wave Overpressure of Thermal Explosion of Charge with Shell

WANG Chang-li, ZHOU Gang, CAI Zong-yi, TANG Yu-zhi, ZHAO Sheng-wei, LI Xun, LIN Ying-rui, CHU Zhe

2012, 33(5):  574-578.  doi:10.3969/j.issn.1000-1093.2012.05.011

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The explosive shock wave pressure is an important parameter which is used for the evaluation of explosion effect, and the characteristic of shock wave pressure is closely related to charge and detonation mode. A measurement method and the results of overpressure of charge with shell measured in the case of thermal explosion were described, and the results were analyzed according to the structure of explosive cave. The results show that the electromagnetic radiation is emitted due to the electrokinetic effect and the friction between explosion product and shell when the charge explodes, and the signal duration and complexity of electromagnetic radiation generated by the charge with shell are different from those generated by the bare charge.

Novel Design of Wide-band Isolation Based on Capacitive Clapboard

HUANG Jing-jian， YANG Yong， TAN Yuan， YUAN Nai-chang

2012, 33(5):  579-582.  doi:10.3969/j.issn.1000-1093.2012.05.012

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For the isolation problem of transmitting-receiving antenna in continuous wave radar, the phase offset in ripple wave-guild with capacitive clapboard was analyzed, the ripple structure was used to improve the isolation of antenna, and a new method was proposed to improve the isolation of transmitting-receiving antenna based on structure counteraction. CST simulation and experimental results show that this method is able to make the isolation reach -80 dB in 400 MHz band. So it has a very huge application value because of its simple structure and low cost.

Research on Electrostatic Field of Helicopter

HAO Xiao-hui，YU Jian-fei，CUI Zhan-zhong

2012, 33(5):  583-587.  doi:10.3969/j.issn.1000-1093.2012.05.013

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The electric field distribution of helicopter rotor wing differs from that of fixed-wing aircraft because of its characteristic of rotation. The charge distribution of helicopter rotor was analyzed using an electromagnetic field analysis software. Simulation result shows that the conclusion that the charges are mainly distributed on the top end of rotor wing as a result of cusp distribution effect, while the charges are distributed evenly in the middle part. an electric charge distribution model of helicopter was proposed based on a dot-charge system according to the numerical simulation results. The simulation result show that the electric field distribution of helicopter is affected obviously by the rotation of rotor wing and the movement of helicopter. The properties of signals generated by the rotation of rotor wing wer reflected by electric field. The lab and field experimental results agree with the simulation results, and the electrostatic charge model of helicopter is viable. The model can be used to research the detection and recognition of helicopter target.

Comprehensive Load Simulation System of Servo Mechanism

YAN Hao， LI Chang-chun， CHEN Ce

2012, 33(5):  588-593.  doi:10.3969/j.issn.1000-1093.2012.05.014

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Abstract: According to the actual load suffered by a servo mechanism in a large launch vehicle, a comprehensive load simulation system was presented, which could simulate the inertia, elastic, friction and constant loads. The inertia load, elastic load and flexible assembling base of servo mechanism were simulated by the mechanical structures, and the friction load and constant load were simulated using a hydraulic system. A complete mathematical model was constructed by modeling the servo mechanism, its flexible structure and the loading hydraulic system. It is shown that this system can reproduce the load characteristics of the servo mechanism in actual situation, and the redundant force of the loading system is suppressed effectively. A load simulation system was developed for simulation of the loads and resonant characteristics, which provides the necessary fundamental facilities for ground test and further research of servo mechanisms.

Numerical Simulation of Three-dimensional Flow Field of Continuous Rotating Detonation

PAN Zhen-hua, FAN Bao-chun, ZHANG Xu-dong, GUI Ming-yue

2012, 33(5):  594-599.  doi:10.3969/j.issn.1000-1093.2012.05.015

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The rotating detonation in a circular combustion chamber was numerically simulated by using a simplified 9-species, 19-step reaction model based on the three-dimensional Euler equations with chemical reaction. The numerical calculation method used is based on a second-order spatially wave propagation algorithm and a two-step Runge-Kutta time marching algorithm. The calculated streak picture is in qualitative agreement with the picture recorded by a high speed streak camera. The three dimensional flowfields induced by a continuous rotating detonation and the distinctive features of the rotating detonations were described in detail. The calculated result shows that the detonation wave can rotationally propagate along the combustible mixture layer, and the lateral rarefaction waves from the air and the previous detonation product lead to the detonation deficit.

An Inverse Problem of a Nonholonomic Non-conservative Mechanical System in Phase Space

ZHANG Yi

2012, 33(5):  600-604.  doi:10.3969/j.issn.1000-1093.2012.05.016

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A dynamical inverse problem of a nonholonomic non-conservative system in phase space was studied. The differential equations of motion were established for non-conservative and nonholonomic non-conservative systems in phase space，respectively. A first-order ordinary differential equation was obtained by differentiating a known integral of the system with respect to time and introducing the Erugin function. Under two circumstances of which the non-conservative forces only rely on generalized coordinates and only rely on generalized momentum, the algebraic equations for determining the non-conservative forces were obtained by the first-order ordinary differential equation and using the differential equations of motion of the systems. The non-conservative forces of the systems can be determined by solving the above algebraic equations. Some examples were given to illustrate the application of the results.

Direction-of-Arrival Estimation Algorithm for Coherent Sources Based on a Vertical VectorSensor Array

BIAN Hong-yu, WANG Jun-lin

2012, 33(5):  605-610.  doi:10.3969/j.issn.1000-1093.2012.05.017

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In order to get the spatial direction-of-arrival estimation of coherent sources, computed angle-of-arrival transient imaging (CAATI) algorithm was introduced in the vector sensor array, and CAATI algorithm using a vertical vector sensor array was proposed. It not only has the advantages of small number of snapshots, less computation and high estimation accuracy, but also has the capability of a vector sensor which can measure the acoustic pressure and particle velocity simultaneously and colocately, so the spatial direction-of-arrival of the target can be achieved with one dimension line array. The algorithm has better real time capability and lower hardware requirement in the practical application. The performance of the direction-of-arrival estimation was simulated and analyzed. The simulation results show that the proposed method is feasible.

Damage Characteristics of Box-like Beam as a Bulk Subjected to UnderwaterExplosion in Near-field

LI Hai-tao， ZHANG Yong-kun, ZHANG Zhen-hai

2012, 33(5):  611-616.  doi:10.3969/j.issn.1000-1093.2012.05.018

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When warship acts against underwater near-field explosion and coupling resonant motion takes place, the damage characteristics of the warship deserves an advanced research. A box-like beam was designed as an object floating on water, and a numerical simulation method was presented to study on the dynamic response of the beam subjected to underwater explosion located closely. Finally，experiments were carried out to verify the simulation method. The results show that numerical results agree well with experimental ones, and it proves the method reasonable. When the first-order mode frequency of beam is close to that of underwater explosion bubble oscillation, with the increase of the ratio of stand-off to maximum bubble radius, the response mode of beam will take a change from plastic bending in sagging condition into elastic whipping motion.

Contact Pressure Distribution During Chemical Mechanical Polishing with Bionic CuttingPolishing Pad

LU Yu-shan, ZHANG Liao-yuan, WANG Ju, WANG Wu-gang

2012, 33(5):  617-622.  doi:10.3969/j.issn.1000-1093.2012.05.019

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In order to improve the uniformity of the contact pressure distribution of chemical mechanical polishing (CMP) and the effects of chemical mechanical planarization, a new model of contact mechanism on CMP was set up based on the Winkler foundation model of elastic theory, and also a kind of method on cutting polishing pad was invented according as phyllotactic pattern of sunflower seed, and then the effects of cutting parameters on the contact pressure distribution of CMP were calculated and analyzed, lastly, the effects of the cutting parameters on the surface profiles of polished wafers were investigated by experiment. The research results show that the contact pressure distribution on polishing wafer surface becomes more uniform and its flatness errors become smaller when cutting parameters are from 0.008 mm to 0.009 mm in clockwise and from 0.005 mm to 0.006 mm in anticlockwise.

Research Notes

Investigation on the Blast Wave Structures of a High-speed Projectile Flying ThroughDifferent Muzzle Brakes

ZHANG Huan-hao， CHEN Zhi-hua， JIANG Xiao-hai， HAN Jun-li

2012, 33(5):  623-629.  doi:10.3969/j.issn.1000-1093.2012.05.020

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The processes of a high-speed projectile flying away from the bores through different muzzle brakes were numerically simulated by using the high resolution Roe scheme and the structured dynamic mesh techniques based on the two-dimensional unsteady Euler equation. The calculated results describe the evolution process of muzzle blast wave structures of different muzzle brakes (without muzzle brake, a three-way muzzle brake and a multi-cavity muzzle brake), and the interaction and evolution processes of them and the projectile are visualized clearly in the computational schlieren images. The numerical results agree well with our previous corresponding experimental shadowgraphs. Moreover, the reducing mechanism of recoil impulse of muzzle brake and the distribution of overpressure areas around the muzzle were discussed in detail, which can praide important guidance for improving the muzzle brake design.

Research on the Effect of Wave to Vertical Launch Missile Water Trajectory

WANG Ya-dong， YUAN Xu-long， ZHANG Yu-wen， LIU Wei

2012, 33(5):  630-635.  doi:10.3969/j.issn.1000-1093.2012.05.021

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During the process between launch and water-exit, sub-launched missile will suffer wave forces, and the wave forces will affect the missile water trajectory parameters to a considerable degree. A random wave model was built using the Pierson-Moscoswitz spectrum and the SWOP direction distributing function, furthermore, equations for calculating wave forces were derived in reference of the section-cutting theory. According to the characteristics of the wave randomness, a series of statistical simulation were carried out by using the Monte Carlo like method. The rules of wave effect to the maximum parameter deviations of the uncontrolled ballistics with the variation of depth were obtained, and maximum ballistics parameter deviations of different sea conditions and wave angles were given, with the changing law described. The simulation method and results have a certain reference value for engineering studies.

Study on Orientation Angle of Two Acoustic Homing Torpedoes Relative to Target withParallel Salvo Launched by Submarine

XIA Zhi-jun， ZHANG Xin-hua， XU Lin-zhou

2012, 33(5):  636-640.  doi:10.3969/j.issn.1000-1093.2012.05.022

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The orientation resolution capacity of surface to two acoustic homing torpedoes with parallel salvo launched by submarine has important influence on command and decision-making of underwater acoustic warfare. Based on the above mentioned parallel salvo method, the mathematic model of the orientation angle of two torpedoes relative to target was established. The orientation angle of two torpedoes to target and its influence factors were calculated and analyzed at different tactical situations. The results indicate the orientation angle of two torpedoes is influenced by alarm distance of oncoming torpedo, salvo interval, salvo optimization coefficient, and homing performance of torpedo etc, and the orientation angle of two salvo torpedoes relative to target is about 3°~7° under the usual tactical condition. As the existing sonar could not differentiate the two torpedoes with parallel salvo veraciously, surface ship gives alarm and counters the two torpedoes as one torpedo usually.