Table of Content

31 May 2011, Volume 32 Issue 5

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Paper

Numerical Simulation of the 3D Flow Fields of a Muzzle Brake and Its Efficiency Calculation

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

2011, 32(5):  513-519.  doi:10.3969/j.issn.1000-1093.2011.05.001

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The process of projectile flying away from a three-dimensional muzzle brake was numerically simulated using the three-dimensional unsteady Euler equations, the high resolution Roe scheme and the structured dynamic mesh techniques. Based on the calculated results, the main characteristics of the complicated three-dimensional transient effect of muzzle brake were discussed in detail, and the numerical calculations are in good agreement with corresponding previous experimental shadowgraphs in our group. Moreover, the efficiency of the muzzle brake was calculated based on our numerical data, and the results also agree well with our previous corresponding experimental results. Therefore, our method is important for the design of the holistic capability of the muzzle brakes in future．

Numerical Analysis of Flow Field Characteristics of Supersonic Submunition with Parachute

WANYAN Zhen-hai, FENG Shun-shan, DONG Yong-xiang, ZHOU Tong

2011, 32(5):  520-525.  doi:10.3969/j.issn.1000-1093.2011.05.002

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The flow field of the supersonic submunition with parachute has a big influence on its aerodynamic performance. The analysis of its characteristics and law of variation can provide reference basis for its design and usage. CFD simulations of flat-faced submunition with disk-streamer parachute were carried out based on multi-block structured grids. Finite volume method and SST turbulence model were used in the simulation. The flow fields were displayed by numerical schlieren method. The results show that the flow field of the submunition with parachute is complicated and has several shock-wave and flow patterns. It is concluded that the flow field of the parachute influences counterpart of submunition and decreases its wake stagnation distance. The type of flow field can be divided into open type and closed type by the neck station of the submunition wake, and has a big influence on the drag coefficient of the parachute. As the Mach number increases, both the detached distance of the submunition's head shock and wake stagnation distances of the parachute and submunition decrease, as well as the decline amplitudes.

Calculation and Analysis on the Combustion Characteristics of a Base Bleed Unit in the Gun Bore

ZHANG Ling-ke, YU Yong-gang, LU Xin, LI Zhi-feng

2011, 32(5):  526-531.  doi:10.3969/j.issn.1000-1093.2011.05.003

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To research the combustion characteristics of base bleed unit in the interior ballistic process, a high pressure burning rate model of base bleed propellant described as de/dt=8.51×10^－8p^0.579 was obtained by utilizing an optimization method based on two sets of closed bomb experimental data with different loading density. Both the general combustion model of base bleed unit in bore and 0-D interior ballistic model of gun-base bleed projectile were established. For a 155mm base bleed unit, the research results obtained under an ideal firing condition are as follows: the difference between the pressures in the base bleed unit and under the projectile base is subjected to an increasing-decreasing-balancing-increasing-decreasing history; the mass of inflow is approximately equal to the outflow at the unit exit; the calculated burning mass of base bleed propellant is about 8.22 g; the maximum change of the muzzle velocity caused by the ignition-combustion delay time is less than 0.4 m/s which could be ignored; the burning mass of base bleed propellant is reduced exponentially with the increase in delay time. The results provide the basic data for analyzing the range dispersion caused by the mass deviation of the propellant from the gun muzzle.

Research on the Fuze-Warhead System Simulation of Terminal Sensitive Munitions

WANG Hong-bo, ZHUANG Zhi-hong, LI Yun-sheng, GONG Li-xian

2011, 32(5):  532-536.  doi:10.3969/j.issn.1000-1093.2011.05.004

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Fuze-warhead system simulation is a key step of terminal sensitive munitions (TSM ) weapon system design. The TSM and target movement models, the TSM swing and delay time estimation model for TSM encountering with target were established, the visualization simulation of beam scanning, target acquisition, burst delay estimation, explosively formed projectile (EFP) warhead burst and target hit processes were realized using the models mentioned above and the TSM/target 3D models. The effects of TSM swing and wind etc. on detector scanning track, target acquisition probability and kill probability of EFP warhead were researched based on visualization simulation, and the fuze-warhead coordination results in the different encounter environments were given.

Research on Wireless Power and Information Synchronous Transmission Method Based on Magnetic Resonance for Fuzes

LI Chang-sheng, ZHANG He

2011, 32(5):  537-542.  doi:10.3969/j.issn.1000-1093.2011.05.005

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A new method which uses a pair of spatial isolated coils in a strongly coupled magnetic resonance regime to achieve the wireless power transmission and information synchronous setting between setter and fuze was proposed based on magnetic resonance theory in order to meet the requirement of weapon systems for power and information efficiency and high-quality synchronous transmission at long distance (meter level) and to solve the problem of widely used electromagnetic induction setting mode for short distance (millimeter level). A circuit model of magnetic-resonance wireless power transmission system was established. Resonance frequency splitting phenomena was observed by analyzing the mutual inductance coupling model, and the exact analytical solution of intrinsic extremum angular frequency was given. Further more, the transmission characteristics of the system in frequency domain and time domain were analyzed by Orcad simulation software. It is found that the current amplitude in pickup coil loop varies sensitively with the operating frequency, and the start-up time of system in resonance condition is microsecond level. The theoretical analysis and simulation results indicate that the method synchronous transmission of wireless power and information is effective and feasible.

Research on Parameters Extraction of Pseudo Code Phase Modulation-Carry Frequency Modulation Combined FuseSignal Based on the Adaptive Window Length of Improved B Distribution

LI Ming-zi, ZHAO Hui-chang

2011, 32(5):  543-547.  doi:10.3969/j.issn.1000-1093.2011.05.006

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The theory and implementation of an adaptive window length time frequency analysis method based on the improved B distribution were presented. The method was used to analyze the in-pulse characteristics of pseudo-code fuse signals, such as pseudo-code phase modulation (PCPM) signal, combined pseudo-code phase modulation and sinusoid frequency modulation (SFM) signal, and combined pseudo-code phase modulation and linear frequency modulation (LFM) signal. The simulation result shows that both the characteristics of carry frequency modulation and phase changed position caused by the pseudo-code can be extracted effectively for SNR=3 dB.

Effect of Substrate Surface Roughness on the Properties of Ni-Cr Alloy Thin Film Transducer Elements

WANG Guang-hai， LI Guo-xin, JIAO Qing-jie

2011, 32(5):  548-553.  doi:10.3969/j.issn.1000-1093.2011.05.007

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The effect of aluminum oxide (95%) substrate surface roughness on the properties of Ni-Cr alloy thin film was studied. The Ni-Cr alloy thin films were prepared on the substrates with different roughness by magnetron sputtering. The micro-structure, adhesion properties and electrical properties of the thin films were studied by scanning electron microscopy, scratch method and four-probe method. The burst voltage and burst current of thin film transducer elements with different substrate surface roughness were measured according to D-optimization method. The results show that the particle size, structural defect, resistivity and adhesion strength of the thin film increase with the increase in the substrate surface roughness. Difference among the burst time of the samples with difference substrate surface roughness gradually decreases with the increase in stimulation amount. The burst time is approximate to 20 μs at the charging voltage of 37 V.

An Assessment Method of Reliability of Initiating Devices Based on Information Measure Equivalency

DONG Hai-ping, ZHAO Xia, CAI Rui-jiao

2011, 32(5):  554-558.  doi:10.3969/j.issn.1000-1093.2011.05.008

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A new method for assessing the reliability of initiating devices based on test information measure equivalency was put forward. According to the principle that more information on reliability from tests on the stress level of low reliability could be gotten over the stress level of high reliability, only one tenth of samples needed by classical method were used to estimate the reliability of 0.999 through test on the stress level of low reliability under the condition of the equivalent information measure obtained by tests between low reliability and high reliability. The assessment result of the new method is consistent with that of the large sample assessment method. The verification test result shows that the new method is feasible for reliability assessment of initiating devices.

Experimental Investigation on the Semiconductor Bridge Plasma Temperature

WU Rong， ZHU Shun-guan， ZHANG Lin， LI Yan， FENG Hong-yan

2011, 32(5):  559-563.  doi:10.3969/j.issn.1000-1093.2011.05.009

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The plasma temperature of the semiconductor bridge (SCB) was measured in real-time based on the relative intensity ratio of two lines of atomic emission spectrum. In the case of different discharge pulses, the plasma temperature and the influence of pulse energy on it were studied. The results show that the plasma peak temperature rises gradually with the increase in initial discharging voltage and capacitance. When the charging capacitance is 22 μF and the initial discharging voltage increases from 21 V to 63 V, the plasma temperature rises from 2 000 K to 6 200 K

Research on Relation between Functional Component Concentration Profile and Combustion Performance of aModified Single Base Propellant

LIU Bo, WANG Qiong-lin, LIU Shao-wu, YU Hui-fang, LI Da, YAO Yue-juan, PAN Qing, WEI Lun

2011, 32(5):  564-568.  doi:10.3969/j.issn.1000-1093.2011.05.010

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A modified single base propellant was prepared from single base propellant grains by impregnating water medium with blasting oil and phlegmatizing it. The concentration profile of functional composition in the propellants is studied by FTIR microspectroscopy. The dynamic and static combustion performance of the propellant was investigated by the means of closed-bomb tests and interior ballistic tests. The results show that the nitroglycerine concentration is along the radius in the form of parabola, and the NA polyester concentration decreases exponentially from the surface inwards on the near surface of propellant. The deeper the nitroglycerine impregnates and the slower the deterrent concentration decreases, the stronger the progressive combustion is and the better the interior ballistic performance is. When the depth corresponding to the maximal value of NG concentration is in proximity to 1/2 of the web and the decrease in the deterrent is the slowest, the progressive combustion is the strongest and the interior ballistic performance is the best.

Fractal Dimension of Pore Structure of Combustible Cartridge Cases

XIAO Le-qin₁, LI Yu₁, ZUO Hai-li₁, ZOU Wei-we₁, LI Ning₁, GUO De-hui₂, ZHOU Wei-liang₁

2011, 32(5):  569-573.  doi:10.3969/j.issn.1000-1093.2011.05.011

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A fractal pore structure model of combustible cartridge case was established by virtue of the fractal geometry. Pore structure information, such as backbone fractal dimension and percolation fractal dimension, of four kinds of combustible cartridge were obtained by mercury intrusion porosimetry (MIP) test. The formation mechanism of fractal pore structure of combustible cartridge was studied with mechanical properties. The results show that the backbone fractal dimension is formed of the space of component and influenced by the number and size of components; the percolation fractal dimension reflects the pore structure of components themselves; and the fractal dimension of pore structure is positively related to the tensile strength of combustible cartridge.

Stabilized Target Tracking Algorithm Using Multi-feature Joint Matching

LI Yu-jue， YAN Jing-long

2011, 32(5):  574-579.  doi:10.3969/j.issn.1000-1093.2011.05.012

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The single feature tracking algorithm of imaging guidance system has a disadvantage of feature instability which can cause the shift of tracking point and the loss of targets in the course of tracking. A multi-feature joint matching method for target tracking was proposed. The drawbacks of tracking algorithm using gray or point feature were analyzed, the corresponding relationship between target tracking algorithm and feature type was induced , and several multi-feature modes were given according to the experiences. The validity of the method using gray and point features as multi-feature was demonstrated. The algorithm is use the gray feature and point feature of target image to calculate the tracking points, respectively. The consistency between the tracking point of each tracking algorithm and the ideal target points was determined according to the measure criteria of comparability between tracking point neighbor and template, a weight coefficient was allocated for each matching algorithm, and an optimal tracking point was given. Besides, the tracking point was taken as a basis of template update. The algorithm overcomes the shortcoming of single tracking method and realizes the stabilized target tracking under the complex background. At last, the tracking video data of a certain missile was used to demonstrate the validity of multi-feature tracking algorithm, compared with a single feature method, the algorithm combines the virtues of multiple features, and the calculated tracking point shift is small. And also, the further improvement of tracking trajectory smoothness and the real-time implementation of algorithm were investigated.

Multiplication Model of Electron Multiplying CCD Based on Single Type of Carrier

ZHANG Can-lin, CHEN Qian, YIN Li-ju

2011, 32(5):  580-583.  doi:10.3969/j.issn.1000-1093.2011.05.013

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The avalanche multiplication principle of electron multiplying CCD(EMCCD) was discussed based on single type of carrier, and a multiplication model was built by using a classic piecewise ionization rate model and avalanche multiplication integral formula. Wolff’s ionization rate model was selected according to the structure and the multiplication gate voltage amplitude of the actual devices. By comparing the theoretical result with the multiplication curve of the actual device, it can be found that only enough fringing field and multiplication area can lead to an adequate signal multiplication. The relationship between the multiplication gate voltage and the total gain of the cascaded boosting EMCCD can be determined by using the model. The calculation indicates that the actual device multiplication curve agreed well with the one of EMCCD theory model.

Experimental Research on the Effect of Air Inlet on Detonation Process and Operating Frequency of PulseDetonation Rocket Engine

PENG Zhen， WENG Chun-sheng， BAI Qiao-dong， LI Ning， MA Dan-hua， JIANG tao，

2011, 32(5):  584-588.  doi:10.3969/j.issn.1000-1093.2011.05.014

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In order to study the impact of different air inlets on detonation process and operating frequency of pulse detonation rocket engine (PDRE) which uses fuel/air as a propellant, three kinds of air inlets, i.e. tangential inlet, tangential/radial mixing inlet and tangential/radial/axial inlet combination, were designed and test on a 80 mm diameter detonation tube, and the multi-cycle work of PDRE was successfully implemented. The results show that the operating frequency and detonation wave of PDRE can be improved by increasing the number of air intakes and setting a reasonable inlet way; the flow speed can be enhanced and the explosive mixture can be evenly distributed in space by using the tangential/radial inlets which achieve the detonation stability at a frequency of 15 Hz. The results have an important reference value to the overall design of optimized PDRE.

Experimental Investigation on Plastic Dynamic Response of Foam Sandwich Arch Subjected to Impact Loading

XIE Qing-hai， WANG Zhi-hua， ZHAO Long-mao

2011, 32(5):  589-595.  doi:10.3969/j.issn.1000-1093.2011.05.015

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The dynamic response of clamped sandwich arch with aluminum foam core under the impact loading of aluminum foam projectile was investigated. The deformation/failure modes of sandwich arch were classified and analyzed systematically. The effects of projectile momentum, face-sheet thickness, thickness of foam core, and radius of curvature on the structural response were analyzed. The deformation/failure modes of sandwich arch can be classified as the indenting failure in the loading area and the large global deformation of the front face sheet, the compression failure and shear failure of the core, and the large inelastic deformation of the back face sheet. The results show that the thicknesses of face sheets and core or the appropriate curvature can be increased effectively to control the permanent deflection of back face sheet, and improve the shock resistance of sandwich arch. The experimental results can provide a reference to the optimum design of cellular metallic sandwich structures.

Design of Launch Acceptability Region Parametric Model for Guided Munitions

ZUO Wei, FENG Jin-fu, ZHANG Jia-qiang

2011, 32(5):  596-601.  doi:10.3969/j.issn.1000-1093.2011.05.016

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A design method of launch acceptability region(LAR) parametric model for guided munitions based on response surface modeling (RSM) was proposed. A polygon of n-vertices was defined to represent the LAR geometric shape，and a mathematical model of LAR was set a group of quadratic polynomials. A number of numerical simulation experiments based on six degree-of-freedom(DOF) model were designed to generate the training data sets and verification data sets. The experimental points corresponding to the training data sets were designed by D-optimal design, and the coefficients of parametric model were determined by a multiple regression analysis of the training data sets. The verification data sets were used to verify whether LAR generated using the fitted coefficients meets the defined criteria，and the experimental points were designed using Sobol sequences. The simulated results show that the designed parametric model could provide an acceptable accuracy of the LAR calculation and effectively reduce the complexity of the LAR calculation program.

Modeling and Experimental Investigation of Load Simulator of Multiple DOF Servo Mechanism

ZHU Xiao-min， YAN Hao, SUN Meng

2011, 32(5):  602-606.  doi:10.3969/j.issn.1000-1093.2011.05.017

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The multiple degrees of freedom (DOF) load property of servo system was analyzed for a load simulating problem of thrust vector control system in a launch vehicle. A new load simulator structure and its mathematical model were presented. The simulation result shows that the output position dynamics of this system is in agreement with that of the actual system. The multiple DOF load property of a prototype experimental system was shown in a sweep frequency test. The simulation and experimental results verify the feasibility of this load simulator structure, which will lay a foundation for developing servo mechanisms of thrust vector control system in heavy launch vehicle.

Research on the Sawing Trajectory of Electroplated Diamond Wire Saw

ZHANG Liao-yuan， CHU Gui-jun， MU Li

2011, 32(5):  607-612.  doi:10.3969/j.issn.1000-1093.2011.05.018

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The cutting process of electroplated diamond wire saw was researched based on impulse and vibration machining theories. From the finite element calculation of different contact states in the cutting process, it is shown that the cutting stress is uniformly distributed along the direction of the workpiece width in a steady state. The mathematical equation of sawing trajectory was established using a superposition principle through the cutting experiment of diamond wire saw, and the trajectory curve was calculated using the equation. The trajectory cure difference between the theoretical and the calculated is less than 15%. The result will be provided the theoretic basis for optimizing the cutting process parameters of diamond wire saw.

Design Method of New Naval Gun Based on Time-oriented Feeding and Random Scheduling

GE Yang, QIU Zhi-ming₁, XIAO Liang₁

2011, 32(5):  613-618.  doi:10.3969/j.issn.1000-1093.2011.05.019

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A new method using a time-oriented design (TOD) and a random scheduling design (RSD) was proposed for some problems, such as low feeding rate, slow ammo-replacement velocity, of naval gun feeding system. A time allotment model of the system and a random scheduling model of multiple operating steps were established. The decision management and simulations of the whole system of the supplying work steps were carried out based on the RSD as well as Markov state transition matrix. It is shown from the integrated mechanical, electrical and control performance simulations that, under the condition of ammo replacement, the average feeding rate of continuous 10 rounds can exceed 35 rounds/min，the ammo replacement time can be less that 4.6 s, and the work efficiency of the optimized system is increased by 20%~30%. This method gives a reference to design the mechanism adapted to the continuously feeding and supplying demands.

Research Notes

Experimental Research on the Impact Compressive Properties of Styropor Concrete

HU Ze-bin, XU Jin-yu, CAO Shan, PENG Gao-feng

2011, 32(5):  619-624.  doi:10.3969/j.issn.1000-1093.2011.05.020

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The dynamic mechanical properties of Styropor concrete（EPSC） added with various volume fractions of EPS at different strain rates were researched by using a 100-mm-diameter split Hopkinson pressure bar(SHPB) apparatus. The effect of EPS volume fraction and strain rate on its compressive strength and deformation were investigated. The experimental results show that the EPSC materials exhibits a strong strain rate dependency. With the increase in volume fraction of EPS, the impact compressive strength of EPSC is declined, and the toughness of EPSC is reinforced.

Flexible-body Dynamics Analysis on Cage of High-speed Angular Contact Ball Bearing

DENG Si-er, XIE Peng-fei, YANG Hai-sheng, GAO Yin-tao

2011, 32(5):  625-631.  doi:10.3969/j.issn.1000-1093.2011.05.021

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A dynamic analysis method for the flexible cage dynamic formula of high-speed angular contact ball bearing was described. The flexible cage dynamic formula of high-speed angular contact ball bearing computational formulation was established using a modified Craig-Bampton component mode synthesis method based on angular contact ball bearing dynamics analysis. The dynamic characteristics of cage of high-speed angular contact ball bearing was analyzed using rigid-flexible multi-body dynamic analysis program ADAMS, and was verified by the computation example of Gupta. The results show that the rotary smoothness of cage will be broken if the ratio of pocket clearance to guided clearance and the ratio of radial load to axial load become too large or too small. The flexible cage runs more smoothly compared to the rigid cage.

Research on Design and Safety Evaluation Method of the Mechanical-Thermal Weak-Link

WANG Fei， ZHANG Fang-xiao

2011, 32(5):  632-635.  doi:10.3969/j.issn.1000-1093.2011.05.022

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In an abnormal high-temperature fire environment, a mechanical-thermal weak-link structure is used to predict the permanent failure before the failure of the strong link (such as explosive initiator), so that the expected safety objective is obtained. A design success is defined to be that the weak-link fails before the failure of the strong link, under which condition the system is safe; and a design invalidation means that the weak-link fails after the failure of the strong link, under which condition the system loses in safety. The probability of safety loss exists due to the uncertainty of the failure temperatures of the weak-link/strong-link. To get the probability of the safety loss, a probability method was used to deal with the uncertainty of the failure temperatures. The integral method and stochastic simulation method were used to compute the results. Finally, a simple sample was given to prove the results given by the two methods to be identical.

An Optimizing Method for Availability-Centric Equipment Support Plan

MAO De-jun, LI Qing-min, ZHANG Zhi-hua

2011, 32(5):  636-640.  doi:10.3969/j.issn.1000-1093.2011.05.023

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The stock and order policy of spare parts influences the availability of equipment. A method was proposed to calculate the expected number of backorders for both repairable and discardable units for the availability of a single part. A model was established to analyze and calculate the availability of multi-echelon equipment. Then the stock and order policies of spare parts were combined and optimized one echelon after another by using the marginal effect, and an entire support plan was got after the optimization. Furthermore, the cost-effective curve of multi-echelon equipment was obtained. An example was given.