Table of Content

31 October 2011, Volume 32 Issue 10

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Paper

Two-phase Flow Simulation of the Charge Structure Which Has Overload Protection with Ignition by Detonation

ZHANG Ding-shan, WANG Hao₂, RUAN Wen-jun₂, GUO Jin-yan₂, FENG Guo-zeng₂

2011, 32(10):  1177-1183.  doi:10.3969/j.issn.1000-1093.2011.10.001

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In order to study the moving and combustion conditions of powder, and the firing and flame propagation characteristics of the charge structure which has overload protection with ignition by detonation, an axial symmetry two dimension-two phase flow model of the layered charge structure using the ignition by detonation was set up based on the experimental study. The main parameters of ignition process were calculated using programming language, and some typical computed results were listed, such as pressure distribution pattern and solid phase void ratio distribution pattern. From the analysis of firing and flame propagation characteristics of the ignition process, it is concluded that the layered charge structure has nicer flame propagation characteristic.

Numerical Simulation and Experimental Study of Ventilated Supercavity of Underwater Projectile

JIN Da-qiao₁, WANG Cong₂, CAO Wei₂, ZHANG Jia-zhong₂, ZOU Zhen-zhu₂

2011, 32(10):  1184-1188.  doi:10.3969/j.issn.1000-1093.2011.10.002

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Fluent 6.3 was applied to simulate the ventilated supercavity of underwater projectile based on the homogeneous equilibrium flow theory. The experiments of underwater ventilated projectile were made by using the projectile device, and the ventilated supercavities of underwater projectile were obtained at 50 m/s and 70 m/s. More ventilation is needed to form the supercavity with the decrease in the cavitation number, and the tail of ventilated supercavity is not closed. The drag coefficient decreases greatly after a supercavity forms, and the drag coefficients nearly remain the same at different velocity. Compared with unventilated projectile, the ventilated supercavitation projectile have small velocity decay rate and longer displacement under the condition of the same muzzle velocity.

Research on a Fast Nonlinear Model Predictive Control Law

XIU Guan, WANG Liang-ming₁, SUN Rui-sheng₁, YANG Rong-jun₁

2011, 32(10):  1189-1194.  doi:10.3969/j.issn.1000-1093.2011.10.003

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Taking nonlinear characteristics, state constraints and magnitude limits of control surface deflections into account, a gliding control law was designed for glide range-extended projectile. For the characteristics of short sampling time and fast system dynamics during the glide control process, the direct multiple shooting method and the real-time iteration scheme were employed to reduce the runtime needed for the receding optimization of nonlinear model predictive control, and the advanced-step scheme was also used to avoid the feedback control delay. The simulation results show that the runtime for solving control law is less than sampling period and the controller could satisfy the control requirement of glide range-extended projectile. The research results provide an important reference for nonlinear model predictive control law design of similar projectiles and rockets.

Interior Ballistic Modeling and Experimental Study on Keyhole Delayed Ignition in Double-chamber

GUO Jin-yan, RUAN Wen-jun, ZHANG Ding-shan, WANG Hao

2011, 32(10):  1195-1199.  doi:10.3969/j.issn.1000-1093.2011.10.004

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In order to make the keyhole delayed ignition device, which could provide a time interval that is shorter than a millisecond, adjust the interior ballistic performance of double-chamber fire mechanism more accurately, a keyhole delayed ignition technology for double-chamber was researched. A structure design scheme of keyhole delayed ignition device was described. An interior ballistics model was established according to the working principle of keyhole delayed ignition device in double-chamber. Besides that, the interior ballistic experiment of double-chamber fire mechanism was done, and the changing situations of pressure in two chambers were measured in the experiment. Then the working process of the keyhole delayed ignition device and the change laws of pressure in each chamber were discussed. By comparing the calculated pressure-time curve with the measured curve, it is shown that the calculated result agrees closely with the experimental result. The interior ballistics model and the test technology can be used to guide the design of keyhole delayed ignition device in double-chamber.

Research and Application of Higher-order Approximate Riemann Solver to Two-phase Flow in Gun

CHENG Cheng， ZHANG Xiao-bing

2011, 32(10):  1200-1205.  doi:10.3969/j.issn.1000-1093.2011.10.005

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In order to improve the ability to capture the complex shock wave of two phase flow on interior ballistic， a split approach was used to handle the advection and source terms of two-phase flow model of gun based on Roe-type approximate Riemann solver. The advection part of the model was solved using a high resolution scheme by reconstruction and flux limiter for total variation diminishing. A two-step and fourth-order Runge-Kutta method was used to solve the source terms. The numerical method was verified using the exact solution of shock tube and source term. By the close comparison between the calculated results and experimental data, it is found that the approximate Riemann solver can be used in the two-phase flow process of interior ballistic. The calculated results can describe the complex two-phase flow in the igniter tube in detail and really. The effect of different factors on the ignition performance was investigated.

Research on Shock/Shock Wave Disturbance Characteristics in Separation of Supersonic Cluster Munition

TAO Ru-yi, WANG Hao, ZHAO Run-xiang, JIANG Kun

2011, 32(10):  1206-1211.  doi:10.3969/j.issn.1000-1093.2011.10.006

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There is complex shock disturbance in the process of separation of supersonic cluster munition. A novel numerical simulation method was proposed to research the shock/shock wave disturbance characteristics in separated flow field of supersonic cluster munition. The calculated solutions are well consistent with the experimental data. It is shown that the shock/shock flow characteristics can be simulated well by the method of Reynolds-averaged Navier-Stokes equations, and splitting scheme AUSM+. The shock/shock interaction, the multiple reflections generated by shocks, and the complicated distribution of pressure and velocity caused by the change in flow direction are found in the process of dispersion. The flow field mechanism of shock/shock flow was explored by the analysis of the specific flow field structure.

Research on Miniaturization of Laser Proximity Fuze

XU Wei， CHEN Qian， GU Guo-hua， HE Wei-ji

2011, 32(10):  1212-1216.  doi:10.3969/j.issn.1000-1093.2011.10.007

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Miniaturization is the key technology and development trend of laser proximity fuze. Based on the operating principle of laser proximity fuze, the miniaturized design requirements were discussed, including fuze system, photodetector selection, optical structure and electrical system, and the design solutions were presented: fuze system which initiates at a fixed distance based on range gating and pulsed laser rangefinding, avalanche photodiode(APD) signal detecting, optical structure of which a transmission optical system is integrated in a receiving optical system, and circuitry based on ARM core MCU and time-to-digital converter(TDC).The design was put into practice. The static experimental results show that the fuze system has small size, low power consumption, high precision and anti-interference capability, and can meet the miniaturized design requirements of laser proximity fuze.

The Analysis of Combination of Chirp Modulation and Pseudonoise Phase Modulation Signal

LIU Jing, ZHAO Hui-chang, ZHOU Xin-gang, ZHANG Shu-ning

2011, 32(10):  1217-1222.  doi:10.3969/j.issn.1000-1093.2011.10.008

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The ambiguity functions (AF) of combination of chirp modulation and pseudonoise phase modulation (PN-chirp) pulse signal and continuous wave were analyzed for the different properties of AFs for finite-duration signals and periodic continuous wave radar signals. Firstly, the AF of PN-chirp pulse was deduced, and the cuts along the delay axis and Doppler axis were discussed respectively. Then the periodic AF of PN-chirp continuous wave was given for analyzing the properties of single-period AF and periodic AF. At the same times, the AFs of PN-chirp pulse and continuous wave were contrasted to show the difference between the two signals. Simulation results show that they have different AF and delay autocorrelation function, which demonstrates that the range ambiguity may appear in PN-chirp continuous wave type detectors; the Doppler autocorrelation function of PN-chirp pulse signal and the single-period Doppler autocorrelation of PN-chirp continuous wave are the same, however, the periodic Doppler autocorrelation shows a better velocity resolution.

Research on Following Penetrating Rate of Homing Guided Missile’s Bunker Blaster Warhead

LI Miao, QI Zai-kang

2011, 32(10):  1223-1229.  doi:10.3969/j.issn.1000-1093.2011.10.009

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Proportional navigation guidance law is used for the terminal trajectory of homing guided missile. While attacking a reinforced fortification, the falling angle dispersion is relatively large so as to ensure a higher hitting accuracy. In addition, the following warhead may be blocked if a reinforced steel bar is not cut off during the opening process of the main warhead, and therefore the successful following penetrating rate of the following warhead is lowered. The effects of falling point distribution and falling angle dispersion of missile, reinforced structure within target, jet current, and size of following warhead on the following rate of bunker bluster warhead were analyzed. The successful following rate of the following warhead penetrating reinforced target was calculated using Monte Carlo random sampling method. The results show that the following rate is direct proportion with jet diameter and inverse proportion with the size of following warhead and falling angle. The following rate is maximum when the missile shoots the target vertically. The research result could give a theory support to the model development of related weapon systems.

Multi-point Temperature Measuring Cook-off Test and Numerical Simulation of Explosive

CHEN Lang， MA Xin， HUANG Yi-min， WU Jun-ying， CHANG Xue-mei

2011, 32(10):  1230-1236.  doi:10.3969/j.issn.1000-1093.2011.10.010

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To investigate the thermal reaction law of PBXC10 explosive, the multi-point temperature measuring cook-off tests were carried out at different heating rates. The explosive temperatures were measured from its edge to its center. An explosive cook-off test model was set up. The numerical simulations were conducted to calculate the explosive thermal reaction. According to measured T-t curves of explosives, the activation energy and frequency factor of PBXC10 explosive were obtained. The thermal reaction characteristics of explosive at various heating rates were analyzed. Based on the direction of heat transfer, the cook-off tests were described in three forms of slow cook-off test, medium cook-off test and fast cook-off test. The thermal explosion processes of PBXC10, JB9014 and JOB9003 explosives were calculated at different temperatures. The results show that the heat sensitivity of PBXC10 explosive is between those of JB9014 and JOB9003.

Research on Microcosmic Mechanical Properties of NQ Propellant

YANG Chun-hai₁, LIAO Xin₁, DU Ping₁, ZHANG Fang₂

2011, 32(10):  1237-1242.  doi:10.3969/j.issn.1000-1093.2011.10.011

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In order to find the reason about inferior mechanical properties of NQ gun propellant(NGP), the topography images, phase images and friction force signal pictures of cut surface of NGP prepared by pre-soaked NQ process(PSNP) and one-off gelatinization process(OOGP) were acquired in Contact Mode and Tapping Mode of atomic force microscopy (AFM). At the same time, the force map of cut surface of NGP prepared by PSNP was obtained and analyzed. The brittle fractured surface picture of sample prepared by PSNP was scanned using the scanning electronic microscope(SEM). The linear expansion coefficients of NGP components were obtained from thermomechanical analysis apparatus(TMA). In conclusion, based on comparative analysis, the results reveal that the inferior mechanical properties of NGP are due to the defects in microstructure of NGP and the dependency of these defects on circumstance temperature. The mechanical properties of NGP could be improved by eliminating these adverse factors whenever possible.

Experimental Investigation on the TNT Equivalence Coefficient of a Rock Emulsion Explosive

FAN Jun-yu， FANG Qin， ZHANG Ya-dong， CHEN Li

2011, 32(10):  1243-1249.  doi:10.3969/j.issn.1000-1093.2011.10.012

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The TNT equivalence of rock emulsion explosives which exploded in free air and outside of corridor conditions was investigated experimentally and numerically. The relationships between the peak pressure and scaling distance for the explosives explosions in free air and outside of corridor conditions were fitted by the test data, and the corresponding TNT equivalent coefficients of the rock emulsion explosives were 0.609 and 0.582, respectively. Besides, the numerical simulation of the tests was conducted, in which the charge weight of the rock emulsion explosives was converted to TNT by the equivalent coefficient obtained in test. The pressure-time histories predicted by the numerical simulation agree quite well with the test data. It is shown that the proposed approach for the determination of the TNT equivalent coefficient of rock emulsion explosives explosions in free air and outside of corridor conditions is feasible. The TNT equivalence of rock emulsion explosives given in this paper can be used in the calculation of shock wave parameters of rock emulsion explosives.

Influence of Combustible Case on Combustion Residue of Modular Charges

QIAO Li-jie， DU Ping， LIAO Xin， WANG Ze-shan

2011, 32(10):  1250-1254.  doi:10.3969/j.issn.1000-1093.2011.10.013

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For the problem of combustion residue produced from some modular charge during firing, the residue amounts of two kinds of combustible cases (slow burning and fast burning) after burning were measured through the closed bomb test. The combustion residue amounts of two combustible cases were also tested in the firing range by taking a bag propelling charge as a reference, and the two residue amounts were compared. The results show that near two-thirds combustion residue comes from the combustible case, and the total amount of combustion residue of the modular charge during firing is reduced by two-thirds after the synthetic resin binder and fiber reinforced material are reduced and the nitrocellulose is increased in the improved combustible case. Thus，the combustion residue of modular charge during firing is basically eliminated.

Infrared Absorption Properties of Silicon Oxynitride Films

ZHOU Shun, LIU Wei-guo, CAI Chang-long, LIU Huan

2011, 32(10):  1255-1259.  doi:10.3969/j.issn.1000-1093.2011.10.014

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Silicon oxynitride films were deposited in a PECVD reactor. The N₂O/NH₃ flow ratio was varied in order to obtain different oxynitride compositions. The films were characterized by X-ray photoelectron spectroscopy, spectroscopic ellipsometry and Fourier transform infrared absorption spectroscopy. The compositions, optical constants and infrared optical absorption properties of silicon oxynitride films were investigated. The results show that the O atomic content increases，the N atomic content decreases， and the Si atomic content keeps nearly unchanged as the N₂O/NH₃ flow ratio increases. The silicon oxynitride films show a dominant infrared absorption peak due to the Si—O/Si—N bond, with the infrared absorption peak located between 11.6 μm (860 cm^-1) and 9.4 μm (1 063 cm^-1) . The position of absorption peak also shifts to a shorter wavelength when the N₂O/NH₃ flow ratio increases. Meanwhile, the width of absorption peak increases firstly and then decreases with the increase in N₂O/NH₃ flow ratio. Moreover, the H content and the refractive index decrease with the increase in flow ratio. Compared with silicon oxide and silicon nitride films, the silicon oxynitride films with a specific composition have the largest width of absorption peak and the strongest intensity between 8 μm and 12 μm, which make them be well suited for the absorber of thermal detectors.

Algorithm of Optical Axis Stabilization Based on Two-axis Polar Coordinate Frame Platform

MAO Xia, LIU Yan, LIANG Xiao-geng

2011, 32(10):  1260-1264.  doi:10.3969/j.issn.1000-1093.2011.10.015

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The importance of post-launched missiles in aerial combat was analyzed on the background of air-to-air missile with infrared seeker. The optical axis of platform was analyzed according to the characteristics of two-axis polar coordinate frame platform, an algorithm of optical axis super-hemisphere stabilization was proposed for the two-axis platform with rolling/swing configuration. The algorithm was efficiently optimized using a dynamic programming method. The simulated results prove that the algorithm can achieve the optical axis super-hemisphere stabilization with high accuracy and fast tracking capability. It has a reference value for practical application.

New Algorithms to Estimate Initial Roll Angle for In-flight Alignment of GPS/INS Guided Munitions

SHE Hao-ping, YANG Shu-xing, NI Hui

2011, 32(10):  1265-1270.  doi:10.3969/j.issn.1000-1093.2011.10.016

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When GPS/INS guided munition needs in-flight realignment after it is fired from a conventional platform, an initial roll angle is difficult to be acquired. To solve this problem, two new algorithms of initial roll angle were proposed with regard to the non-spin and low-speed spin of projectile. The relationships between the roll angle and the transverse angular rates and attitude angle rates were derived from attitude kinematics equations. The measured values of angular rate gyroscopes and GPS velocity were used to obtain optimal estimation of roll angle based on least squares estimation. Simulation results and performance analysis show that the random and constant wind during flight are the main factors affecting estimation accuracy. The estimated errors are less than 3° under different typical levels of measurement and flight conditions. The algorithm can be used to estimate the roll angle during in-flight coarse alignment.

Dynamic Responses and Failure Modes of Reinforced Concrete Beams with Flexible Supports Under Blast Loading

CHEN Wan-xiang, GUO Zhi-kun, YE Jun-hua₂

2011, 32(10):  1271-1277.  doi:10.3969/j.issn.1000-1093.2011.10.017

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Calculation methods of elasto-plastic dynamic response of reinforced concrete beams with flexible supports under blast loading were derived based on the theory of Euler-Bernoulli beam. The main factors such as the dynamic loading characteristics, stiffness and damping of supports that have influence on the failure modes were investigated according to the criterion of dynamic ultimate resistance for reinforced concrete beams. Results show that the failure mode of reinforced concrete beam with flexible supports under blast loading not only depends on the loading characteristics, but also on the supporting conditions. The shearing failure times of reinforced concrete beams with flexible supports are delayed greatly, and the shearing failure tends to occur at higher dynamic loading rate, larger blast impulses or blast overpressures. The failure modes of the beams are transferred from flexural failures to shearing failures with the increase in supporting stiffness, and the failure times are delayed with the decrease of supporting stiffness. The peak deflection values, moments or shearing force are attenuated quickly with the increase of supporting damping, but the failure modes and failure times are not changed greatly. The supporting damping seems to have no obvious effects on increasing the ultimate resistance of reinforced concrete beams with flexible supports.

Sampling-based Evaluation of Firing Efficiency of Cargo Round

LI Bin， ZHANG Jian， YU Hai-yong

2011, 32(10):  1278-1281.  doi:10.3969/j.issn.1000-1093.2011.10.018

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Aiming at the deficiency of pixel-simulation and holomorphic-simulation used in calculating the damage area of cargo round, a resolving method based on sampling was proposed. By sampling in the target area, calculating the damage situation of sample points, the method can evaluate the damage effect and effectively solve the problem of calculating overlapped damage area of cargo round. The theory of sampling method was discussed, and the mathematical models of target area, impact point, cargo round scattering, coordinate transformation and efficiency evaluation were established. The precision of the method was approved by a representative calculation example. The method can be used for tactical and technical index demonstration and researching on how to use weapon equipment for maximal efficiency in battle.

Vibration and Noise Reduction of a Double Crank Four Ring-Plate-Type Cycloid Speed Reducer

YANG Bing， LIU Yan

2011, 32(10):  1282-1286.  doi:10.3969/j.issn.1000-1093.2011.10.019

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A double crank four ring-plate-type cycloid speed reducer is a new type speed reducer. However, the speed reducer generates large noise and vibration which prevent its popularization and application to some extent. The noise and vibration tests of the double crank ring-plate-type cycloid speed reducer driven by three gears were completed using the Artemis integrated multi-channel noise and vibration analysis system. The vibration and noise characteristics of the speed reducer main parts at different rotational speeds and different loads were analyzed. The main noise source in the speed reducer was identified as the noise caused by the mesh of the cycloid gear and pin wheels. The relevant noise and vibration reduction measures were proposed for the noise source and the speed reducer box. The improved speed reducer was tested and analyzed. The results show that the vibration and noise reduction are achieved effectively through the structural improvements of the box and the ratio changes of the cycloid gear and pin wheels. The conclusions provide the basis for further design of vibration and noise reduction.

Fault Diagnosis Strategy Design of Electronic Equipment Based on Multivalue Test

WANG Cheng-gang， LIU Zhi-yuan， YANG Zhi-yong

2011, 32(10):  1287-1291.  doi:10.3969/j.issn.1000-1093.2011.10.020

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For complex electronic equipment, the practical test output may be variform when it fails. A great deal of information would be ignored if a binary test is applied, and the test precision and efficiency would also be decreased. A heuristic function based on Huffman coding with r elements was constructed, and a fault diagnosis strategy design algorithm based on multivalue test was put forward. The multivalue outputs were taken as the independent signals, and then a fault diagnosis strategy design algorithm based on dependency matrix extension was presented. Finally, an example shows that the fault isolation precision is improved and the algorithm is effective. It offers an efficient algorithm to the diagnosis strategy design of complex electronic equipment.

Research on Safety Performance Evaluation Method of Fault-prediction Technology Based on Misclassification Cost

HUANG Da-rong， SONG Jun, ZHAO Gang

2011, 32(10):  1292-1297.  doi:10.3969/j.issn.1000-1093.2011.10.021

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A new safety performance evaluation of the fault-prediction technology was researched based on misclassfication cost. First of all, a misclassification cost model for the statistical data of two fault-classificatory sets was constructed based on the inaccurate characteristic of probability theory, and the fault-direction decision rules of the running state were established by considering the minimum misclassification cost. Secondly, a misclassification cost model of numerous fault-classificatory sets was constructed, and the fault-direction decision rules were established by considering the minimum misclassification cost. And a basic flow of safety performance evaluation was provided for the fault prediction technology. Finally, the effectiveness of the model was verified by taking the fault detection of launch vehicle control system as an example, and the further development trend of the fault prediction technology was discussed.

Adaptive Control of a Nonlinear System with Input Backlash

GUO Jian, WU Yi-fei, CHEN Qing-wei, YAO Bin

2011, 32(10):  1298-1304.  doi:10.3969/j.issn.1000-1093.2011.10.022

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Two kinds of adaptive controllers were developed for a class of nonlinear system with input backlash. For the inherent non-smooth and dynamic nonlinear nature of the unknown backlash, it is linearly parameterized globally with bounded modeling error. An adaptive controller and an adaptive robust controller for nonlinear system were designed in the case of unknown input backlash, parameter uncertainty and external disturbances. The proposed adaptive control law ensures the asymptotic tracking stability of closed-loop system. But the violent chatting limits its application in practice. The adaptive robust control ensures that all signals of the closed-loop system are bounded and the tracking error is kept in a desired precision. The theoretical analysis and simulation results show the validity of the proposed controllers.