水下无人系统学报

Convective Heat Transfer on Solid of Revolution with Local Heating under Flow-Directional Electromagnetic Force

LI Hui, LIU Zong-kai, ZHOU Ben-mou, JIANG Yong

2016, 24(5): 321-324. doi: 10.11993/j.issn.1673-1948.2016.05.001

[Abstract](896) [PDF 786KB](470)

Abstract:
In this paper, based on the energy equation of convective heat transfer and the basic control equations of flow field, simulation is conducted with the software Elmer to analyze the local convective heat transfer characteristics of the solid of low velocity revolution under the action of flow-directional electromagnetic force. The results show that the power of convective heat transfer increases when the electromagnetic force is exerted around the solid of revolution, and with the increase in the electromagnetic force, the fluid within the scope of the electromagnetic force gains more motion energy to drive the high temperature fluid near the wall of the solid of revolution leaving away more rapidly, thus the wall can contact more low-temperature fluid, resulting in more heat exchange and higher convective heat transfer power. The research in this paper can provide reference for the design of the thermal environment of the underwater weapon and the counter measures.

Discussion on Assembly Technique of Torpedo Electronic Section

HUANG Chao

2016, 24(5): 325-328. doi: 10.11993/j.issn.1673-1948.2016.05.002

[Abstract](963) [PDF 237KB](444)

Abstract:
The assembly of electronic section of a torpedo is of great importance in whole torpedo assembly, affecting the performance of the torpedo. In this paper, the existing assembly technique is reviewed, and the key procedures of the assembly technique are summarized, such as sealing, blind-mating, assembly of cable, and assembly check. Furthermore, a concept of digital assembly for the assembly of torpedo electronic section is proposed to solve the problem in the existing assembly technique, and the application of digital assembly to torpedo electronic section is discussed.

Waveform Analysis of Acoustic Doppler Flow Measurement

ZHANG Yu-hang, YANG Yun-chuan, LÜ Lin-xia, WANG Hai-lu, YUE Ling, LI Jin-ming

2016, 24(5): 329-333. doi: 10.11993/j.issn.1673-1948.2016.05.003

[Abstract](812) [PDF 640KB](520)

Abstract:
To improve the velocity accuracy and range resolution of Doppler flow measurement technology, this paper comprehensively compares the waveforms of the signals with large product of time-width and bandwidth between the Costas frequency-coded signal and several phrase-coded signals considering practical application condition. It is revealed that binary phase shift keying(BPSK) signal is more benefitial to achieving high velocity accuracy and range resolution, and gains better anti-reverberation ability at low speed. The accuracy of Doppler frequency is estimated in simulation by using the complex autocorrelation algorithm. The results show that BPSK signal can help to obtain the minimum variance of velocity characterization, and is more suitable for the measurement of high-resolution Doppler flow velocity.

A Method of Target Tracking Data Association in Sea Clutter Background

CHEN Xiao, LI Ya-an, YU Jing

2016, 24(5): 334-339. doi: 10.11993/j.issn.1673-1948.2016.05.004

[Abstract](1221) [PDF 594KB](564)

Abstract:
The problem of surface ship target tracking in strong sea clutter environment is theoretically analyzed and simu-lated by employing the nearest neighbor filter(NNF) algorithm and the probabilistic data association filter(PDAF) algorithm. Based on the PDAF algorithm, the concept of twice-weighted distance is introduced for the dense sea clutter environment to improve the correlation probability value calculation method of the existing PDAF algorithm, and the single target tracking in the sea clutter environment with different densities is simulated. Simulation results show that the improved algorithm can improve the tracking performance in dense sea clutter environment, hence realize the non-maneuvering target tracking more effectively and reliably. This research may provide reference for accurate tracking of surface ship targets in sea clutter background.

Waveform Design and Echo Characteristic of Underwater Carrier-free Ultra-Wide Band Signal

HOU Xin-yu, CHEN Hang

2016, 24(5): 340-345. doi: 10.11993/j.issn.1673-1948.2016.05.005

[Abstract](988) [PDF 530KB](487)

Abstract:
The design of signal waveform is very important for improving torpedo homing performance under complex underwater acoustic environment. Ultra-wide band signal has many advantages in target detection, such as high resolution, strong penetrability, and low duty ratio. In this paper, According to the Ricker waveform of underwater acoustic signals modulated by different bit baker codes, the signal′s bandwidth, frequency spectrum and energy uniformity within a frequency band are analyzed, a Ricker signal modulated by a 4 bit baker code is optimized as an underwater carrier-free ultra-wide band signal. Based on this kind of ultra-wide band signal, the echo characteristic simulation analysis of submarine target is carried out, and the influences of incident angle and signal waveform with different pulse interval on the echo of multi-highlight target are obtained. Simulation results verify the feasibility of this kind of pulse signal in underwater target detection, and may provide reference for further research on application of ultra-wide band signal to underwater target detection.

Waveform Design and Analysis of Torpedo Acoustic Homing in Shallow Water

LEI Jiang-tao, DONG Meng, ZHANG Guo-feng

2016, 24(5): 346-350. doi: 10.11993/j.issn.1673-1948.2016.05.006

[Abstract](1180) [PDF 1147KB](460)

Abstract:
As one of three major design factors of a torpedo active acoustic homing system, waveform design determines the anti-reverberation capability and accurate parameter estimation of the torpedo active acoustic homing system. In this study, ambiguity function is adapted to analyze the anti-reverberation capability, range and velocity resolution of three typical wideband waveforms, i.e. linear frequency modulation(LFM) waveform, pseudo random binary phase coding waveform, and Costas waveform. Simulation results demonstrate that the pseudo random binary phase coding waveform has the best anti-reverberation performance and joint resolution of velocity and range, and it is suitable to low speed target detection and identification in shallow water. This research may provide a reference for design of torpedo active acoustic homing waveform.

Impeller Modal Testing Based on Measuring Points Optimization and Acceleration Sensors

LIU Jing-yun, SUN Tao, PENG Bo, YI Yin, YAN Hai, GAO Hui-zhong

2016, 24(5): 357-361. doi: 10.11993/j.issn.1673-1948.2016.05.008

[Abstract](1121) [PDF 1101KB](1496)

Abstract:
Since torpedo turbine impeller is small and light, the number of acceleration sensors has a direct effect on testing precision and measured order of impeller modal. In order to reduce the number of testing points for the purpose of decreasing the effect of additional mass on the natural frequency of the impeller, modal confidence analysis is carried out by introducing the finite element grid model and the modal calculation result of the impeller into the software LMS Virtual.lab. The response number and positions of the measuring points, as well as the position and direction of the excitation point, in impeller modal testing are optimized. The first 3 orders of natural frequency and vibration modes of the impeller are identified with acceleration sensors on the basis of pre-test. The vibration modes of the modals from testing coincide with that from calculation, and the maximum error of natural frequency is 3.3%. This research indicates that the optimized position and number of sensors can improve modal testing effect, but cannot eliminate the influence of additional mass on the natural frequency of the impeller completely. It is suggested that the non-contact laser vibrameter technology be employed to obtain more accurate impeller modal parameters.

Simulation on Flow around Cylindrical Projectile in Water Based on DES model

ZHANG Chi-yu, GUO Rui, LIU Min, LIU Rong-zhong, ZHOU Hao, CHEN Liang

2016, 24(5): 362-367. doi: 10.11993/j.issn.1673-1948.2016.05.009

[Abstract](937) [PDF 896KB](515)

Abstract:
Based on the software Fluent, the flow around a cylindrical projectile in water with high Reynolds number is simulated by using the detached eddy simulation(DES) method. The flow characteristics of the cylindrical projectile are analyzed at the flow rate of 25 m/s, and the lift coefficient, the drag coefficient and the Strouhal number, as well as the periodic alternatively shed Karmen vortex structure, are obtained. The mean velocity of flow field in different cross section and the mean steady pressure coefficient at cylinder circumference are analyzed. The image law is well consistent with that from the known large eddy simulation(LES) method. Further, the projectile drag coefficient and the Strouhal number at different speeds are analyzed, and the results show that with the increase in flow rate, the drag coefficient and the drag against the cylindrical projectile moving in water decrease, while the Strouhal number increases, inferring higher frequency of vortex shedding at both sides of the cylindrical projectile. When the vortex shedding frequency is close to the natural frequency of the projectile, resonance will occur to harm the projectile. This research may provide reference for design of projectile in underwater weapon warhead.

Design of Vibration Isolator Against Underwater Explosion for LED Light Source

WANG Wen-guan, ZHOU Li

2016, 24(5): 368-373. doi: 10.11993/j.issn.1673-1948.2016.05.0010

[Abstract](1470) [PDF 1094KB](501)

Abstract:
To directly observe and analyze the impulsion characteristics of the bubbles induced by underwater explosion, a light-emitting diode(LED) light source and its vibration isolator are designed. The characteristics of the vibration isolator under non-contact underwater explosion load are simulated. Finite element models of the LED, its vibration isolator, protection cover and water medium are built by using the software Hypermesh. Then the acoustic-structural coupling method in the software ABAQUS is employed to analyze the dynamic response of the isolator. By analyzing the time history curve of acceleration of two terminal points on the isolator, it is concluded that the medium density difference between inside and outside of the structure will affect transmission path of explosion shock wave, and the fixing mode of the structure will influence illumination of the LED light source. This research may provide reference for design of vibration isolator against underwater explosion for small structure.

Discussion on Five Problems in Torpedo Test and Evaluation with Improvement Suggestions

HE Cheng-gang, GAO Jiang, WANG Hao

2016, 24(5): 374-378. doi: 10.11993/j.issn.1673-1948.2016.05.011

[Abstract](964) [PDF 206KB](464)

Abstract:
Five problems existing in the torpedo test and evaluation are discussed, and corresponding improvement methods are suggested as follows: 1) Using the statistical method of repeated failures for reference, the repeated unqualified items can be changed to a single statistics to eliminate the impact of the difference of test plans on the pass rate; 2) Based on the existing definite number test, the requirement and principle of the “adding test” are analyzed and determined to solve the inadequate and incomprehensive problems of a test; 3) According to the sufficiency requirement of sample size and the change condition of technical status, whether interrupt or retry the torpedo test after the technical status change is analyzed and determined to clarify the test procedure and avoid mistake; 4) The availability dependability capability(ADC) effectiveness evaluation model is employed to define the work reliability and the ability in sea trial, thus the problem that the work reliability and the ability are repeatedly judged to be unqualified can be solved; and 5) According to the definition of load reliability, the requirement of consistency before and after the torpedo load test, and the actual usage analysis of a torpedo, we clear the detecting depth and breadth after the test are clarified. The methods mentioned above may be applicable to compiling torpedo test outline and modifying the evaluation criteria.

Torpedo Approval Lake Test in Actual Combat Condition: Discussion

SUN Quan

2016, 24(5): 379-383. doi: 10.11993/j.issn.1673-1948.2016.05.012

[Abstract](850) [PDF 182KB](466)

Abstract:
The torpedo approval test in actual combat condition is very important for ensuring the equipment reliability. For the purpose of conducting torpedo approval lake test in actual combat condition, the performance of a modern torpedo and its actual combat characteristics are considered, the requirements of the test and the related hardware resource are analyzed, and the key testing points and items of the approval test are presented. This study may provide a reference for torpedo approval lake test, and may be helpful for torpedo approval sea trial, soldiers training, torpedo research test and acceptance test in lake, and the tests of other underwater weapons such as mine and decoy.

Vector Control of Dual Three-phase Induction Motor

LI Hong, ZHANG Peng-ju

2016, 24(5): 379-383. doi: 10.11993/j.issn.1673-1948.2016.05.007

[Abstract](736) [PDF 434KB](506)

Abstract:
Dual three-phase induction motor has been widely applied to such fields as ship propulsion, aviation, aerospace, new energy vehicles, and nuclear power because of its high reliability and stability. There are 64 voltage space vectors in six-phase induction motor driven by the six-phase voltage source inverter. The α-β subspace is divided into 12 sectors, and the reference vector in each sector is composed of 4 maximum vectors. Based on the rotor flux oriented control method and voltage vector space decoupling method, a six-phase space vector pulse width modulation(SVPWM) speed control system is established in the MATLAB/Simulink environment. Simulation results show that the system′s torque ripple and stator current harmonics are small, the speed response and flux response can effectively track, and the system possesses satisfactory dynamic and static response capability.

Force Analysis and Simulation of Optical Fiber Clew for Wired Communication Buoy

ZHAO Jin-cai, TANG Wei-jiang, SUN Tie-sheng

2016, 24(5): 384-389. doi: 10.11993/j.issn.1673-1948.2016.05.013

[Abstract](998) [PDF 367KB](326)

Abstract:
To solve the end plate extrusion deformation problem of the wired communication buoy′s optical fiber clew, which is made from lightweight material, in the winding process of guidance optical cable, this paper analyzes the force and deformation of the end plate and shell by considering the structure features and winding process of the optical fiber clew, and employs the theory of plate and shell mechanics to derive the balanced differential equation, geometric equation and physical equation of the end plate deformation. Moreover, a simulation of the end plate deformation is conducted according to real boundary condition and the characteristics of the lightweight material, and the main factors affecting the end plate deformation are determined. The research is of benefit to the design of the wired communication buoy′s optical fiber clew.

Analysis on Internal Flow Fields in Different Launch Valve Core Structures in Emergent Launching Condition

CHEN Wei-bin, WANG Xian-ming, DUAN Hao, WANG Yun

2016, 24(5): 390-395. doi: 10.11993/j.issn.1673-1948.2016.05.014

[Abstract](855) [PDF 1449KB](406)

Abstract:
A program-controlled valve, which can complete launch mission in emergent condition, is vital to ensure successful launching of a torpedo in war. To explore whether the valve core can keep good launching quality in emergent conditions, the finite element simulation software FLUENT is employed to simulate the internal flow fields in three kinds of valve core structures. Contrast analysis show that the double trapezoidal-double rectangular valve core structure can effectively reduce the loss during energy going through the valve core, hence enhance launching quality. This research may provide a reference for further optimization of transient energy injection and control as well as reduction of transient noise during launching process.

Influence of Tube′s Inner Diameter on Interior Trajectory for Underwater Vehicle Ejection Launcher

MA Hui

2016, 24(5): 396-400. doi: 10.11993/j.issn.1673-1948.2016.05.015

[Abstract](649) [PDF 678KB](412)

Abstract:
To balance launch efficiency and size of an underwater vehicle launcher and design proper inner diameter of the launching tube, the many-to-many interface scheme is adopt to overcome the simulation difficulty of gapless slipping between the walls with holes, and a simulation model for solving coupled unsteady flow field, piston and vehicle movement is built. Interior trajectory simulation with different tube′s inner diameters is accomplished by secondary development in software Fluent, and the calculated flow fields as well as the movement time history curve are analyzed. Simulation results reveal that the inner diameter of the tube shows obviously positive correlation with the launching efficiency within a certain scope, while the influence of the inner diameter gradually weakens as the inner diameter increases, and finally the out-tube efficiency tends to be stable. It is concluded that the simulation of underwater vehicle launcher based on many-to-many scheme is reliable, and may be applied to design of underwater vehicle ejection launcher.

2016 Vol. 24, No. 5

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