水下无人系统学报

Factors Influencing Water Entry Parameters of Torpedo-Parachute System

WANG Zhi-jie, MA Xia, LIU Yan-bo

2010, 18(4): 241-245. doi: 10.11993/j.issn.1673-1948.2010.04.001

[Abstract](1252) [PDF 213KB](797)

Abstract:
For the water entry parameters analysis of torpedo-parachute system, the existing studies only considered torpedo’s dropping speed, attitude angle, and wind speed, but neglected other factors. This paper establishes a three-dimensional space trajectory model of torpedo-parachute system, and simulates torpedo trajectory in air. According to the simulation results, the influences of the comprehensive factors on water entry parameter and trajectory stability of the torpedo-pa rachute system are analyzed, and some valuable conclusions are drawn. Those factors include dropping altitude, speed and attitude angle of a torpedo, design parameters o f a parachute, and wind speed. This research may provide a technical support to air drop test and firing form scheduling of torpedoes.

Parametric Modeling of Torpedo Shell Structure Based on APDL

HE Hui-jiang, LI Nan

2010, 18(4): 246-248. doi: 10.11993/j.issn.1673-1948.2010.04.002

[Abstract](1589) [PDF 158KB](802)

Abstract:
Modeling Torpedo shell structure is very important to torpedo overall design as well as shell structure optimization. The traditional torpedo shell structure modeling method establishes model with GUI via CAD drawing software, how ever once some parameters change, designers have to rebuild the model from the very beginning and result in waste of design resources. This paper presents a parametric modeling method for the torpedo shell structure based on the ANSYS parametric design language (APDL), with which remodeling can be automatically performed by computer through simply changing a few design parameters. The present method can save much design resources and facilitate the later torpedo shell optimization.

Application of FAHP to Torpedo Operational Effectiveness Evaluation

SONG Bao-wei, LI Nan, MAO Zhao-yong

2010, 18(4): 249-252. doi: 10.11993/j.issn.1673-1948.2010.04.003

[Abstract](1253) [PDF 150KB](639)

Abstract:
Torpedo system is a complex system with many fuzzy or uncertain factors, which to a certain extent lead to fuzzy operational effectiveness of torpedo. Traditional evaluation methods ignore this problem, inevitably resulting in a certain risk in the evaluation results. We introduce fuzzy analytic hierarchy process (FAHP) into the operational effectiveness evaluations of several types of torpedoes to reduce the risk of evaluation results, decompose a complex problem in to a series of fuzzy factors, then determine the relative importance of each factor in every level by pair-wise comparison, and finally determine the sequence of the factors according to the irrelative importance, conclusions show that the evaluation results obtained by the proposed methods is more safety and reliable.

Application of iSIGHT to Optimization Design of Water-exit Trajectory for Missile Carrier

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

2010, 18(4): 253-257. doi: 10.11993/j.issn.1673-1948.2010.04.004

[Abstract](1796) [PDF 216KB](659)

Abstract:
In the design of the water-exit trajectory of the unpowered sub-aunched missile carrier from deep water, a large number of design parameters and complex constrains make the manual design and optimization of control scheme a complicated job, which needs much experience and techniques and cannot assure the best result. In this paper, the authors apply the software iSIGHT in the optimization design of water-exit trajectory control scheme. Hence, the automation o f design process is realized, the design efficiency is improved, and the optimized water-exit trajectory control scheme for missile carriers is achieved.

Strength Prediction of Underwater Complicated Target Based on Planar Element Method

FENG Qi

2010, 18(4): 258-262. doi: 10.11993/j.issn.1673-1948.2010.04.005

[Abstract](1533) [PDF 351KB](675)

Abstract:
When underwater complicated target is irradiated by high frequency signals, the comprehensive effect of all parts on sonar irradiation plays an important role in the reflection of the target. Aiming at this problem, the planar element method is introduced into sonar target computation. The surface of any arbitrary shape target is divided into many small curved faces by 3DS MAX software, which are approximated by planar elements. Then underwater complicated target strength is predicted by Kirchhoff acoustic scattering theory. The present method has solved the problems that the existing acoustic high light model is inaccurate because of ignoring the geometry of target, and the numerical integration can not calculate the target strength of irregular objects. The availability of the present method is verified by numerical calculation and experiment.

Influence of ULA Structure on PTRM Array Spatial Gain

LIU Jia-liang, WANG Hai-yan, JIANG Zhe, ZHANG Ying-feng

2010, 18(4): 263-267. doi: 10.11993/j.issn.1673-1948.2010.04.006

[Abstract](1354) [PDF 235KB](652)

Abstract:
In order to overcome the complexity of acoustic channels multipath, theoretical expressions of the multi-element passive time reversal mirror (PTRM) are deduced, hence the principle of obtaining spatial gain by PTRM is proposed, and the influence of uniform linear array (ULA) structure on PTRM array spatial gain is studied theoretically for the first time. The proposed PTRM method is validated and analyzed with simulative data, and the computational results indicate that: (1) With the increase of array element number, PTRM array spatial gain is heightened; (2) When the element spacing is long enough( longer than the half of wave length to let noise become incorrelate), element spacing has little effect on PTRM array spatial gain, w here signal to noise ratio (SNR) influences the quality of communication predominantly.

Effect of Ship Speed on Bubble Wake Geometry Characters

TIAN Xue-bing, GU Jian-nong, ZHANG Zhi-hong, WANG Chong

2010, 18(4): 268-271. doi: 10.11993/j.issn.1673-1948.2010.04.007

[Abstract](1526) [PDF 207KB](630)

Abstract:
In order to understand the effect of ship speed on bubble wake geometry characters, explore the effect law of different scale bubbles on wake, and provide theoretical basis for acoustic detection of ship bubble wake and torpedo wake homing, this study adopts parabolic Reynolds-averaged Navier-Stokes ( PRaNS) equations, the bubble transport equation and the k-ε turbulence model are used to estimate the bubble number density distribution in ship’s far field wakes, numerically simulates the ship bubble wake geometry characters under different speeds for two typical ships, and the results agree well with the experiments. It shows that ship speed has little effect on bubble wake geometry distribution, but has significant effect on bubble number density in ship wakes. The faster the speed of ship, the higher the bubble number density in the ship wakes with same wake age, and the clearer the wake character. The bubbles with 10 μm radius have the largest elevation, the bubbles with 52 μm radius have the smallest elevation, and the bubbles with radius between 30~ 50 μm live longest. So the wake detection should be focused on the bubbles with radius between 30~ 50 μm.

Design of Torpedo Wake Homing System for Higher Trajectory Accuracy

LIU Li-li, SU Shao-jing, HUANG Zhi-ping, LIU Chun-w u

2010, 18(4): 272-276. doi: 10.11993/j.issn.1673-1948.2010.04.008

[Abstract](1317) [PDF 223KB](706)

Abstract:
Three key problems in wake homing design are analyzed theoretically to improve the accuracy of torpedo trajectory. Firstly, a new method for forming wake detection sign by comparing the cumulantion in a time period is presented to solve the inaccurateness caused by the randomicity of wake. Secondly, the orientation and the width of the wake a re calculated by using the coordinates of the points w here torpedo entering and leaving the wake, thereby the torpedo can run following the wake orientation with simpler and more effective way than the conventional methods. Finally, the effect of the wake break on guidance and trajectory is introduced, and the corresponding technique to avoid the misguidance is presented. Analysis results show that the present scheme can improve the accuracy of trajectory guidance.

Cooperative Navigation for Multiple AUVs Based on a Single Leader with Unknown Currents

LI Wen-bai, LIU Ming-yong, GAO Jun-chai, PEI Xuan

2010, 18(4): 277-281. doi: 10.11993/j.issn.1673-1948.2010.04.009

[Abstract](1860) [PDF 327KB](688)

Abstract:
Cooperative navigation of autonomous underwater vehicles (AUV) is important in marine applications, where currents estimation is one of the major challenges. In this paper, an “ unknown-but-constant ” model for currents is assumed. Then, the cost function of localization transition for cooperative navigation of multiple AUVs with disturbance of currents is constructed via analyzing the localization principle of cooperative navigation with a single leader communication and navigation aid-AUVs (CNA) . The optimal estimation principle for localization navigation is given by minimizing the cost function. Through this principle, the error estimation of currents and the cooperative navigation algorithm are obtained. Thus, accurate localization for AUV can be realized by using this navigation algorithm. Simulation results show that this algorithm solves the cooperative navigation problem with good real-time property and high precision. This study may provide a theoretical basis and research tools for the overall design of multi-AUV system, navigation path planning and tracking theorem.

A Transfer Alignment Method of SINS for Shipborne Torpedo

WANG Yan, WANG Li-wen

2010, 18(4): 282-286. doi: 10.11993/j.issn.1673-1948.2010.04.010

[Abstract](1849) [PDF 196KB](816)

Abstract:
Addressing the initial alignment of strapdown inertial navigation system (SINS) for shipborne torpedo, we present a new transfer alignment method on moving base, i. e. sequential matching scheme. The scheme adopts the “first angular rate matching, then velocity plus attitude matching” method to make the misalignment angle converge rapidly when angular motion of the base is slight. The oscillation during the interim is suppressed by keeping measurement noise covariance or by using adaptive Kalman filter. We compare the sequential matching with velocity plus attitude matching by using Kalman filter algorithm. Simulation results show that the proposed method has shorter response time and more general applicability.

New Application of Federated Filter in INS/GPS/DVL Integrated Navigation System for AUV

WANG Xiao-feng

2010, 18(4): 287-290. doi: 10.11993/j.issn.1673-1948.2010.04.011

[Abstract](1638) [PDF 171KB](654)

Abstract:
Aiming at the problem that autonomous underwater vehicle(AUV) navigation system can not fulfill the requirement of high precision for navigation and location because of the limitation of underwater environment, an inertial navigation system/global position system/Doppler velocity log (INS /GPS /DVL) integrated navigation system fusing multi-sensor information is proposed. In this integrated system, the federated Kalman filter is adopted, and each navigation subsystem is optimized through dynamic information sharing coefficient to improve the performance of the integrated navigation system. Simulation results show that the present system can sufficiently extract the information of the navigation sensors, and effectively improve AUV navigation system’s precision and underwater localization ability.

Predicting the Occurrence of Contact Loss Between Pairing Elements in Spatial Wobble-plate Mechanism

ZHOU Qi-zheng, WANG De-shi, GAO Sheng-yao

2010, 18(4): 291-294. doi: 10.11993/j.issn.1673-1948.2010.04.012

[Abstract](1223) [PDF 257KB](689)

Abstract:
Based on the theory of spatial mechanics, the structure model was abstracted from wobble-plate engines. The bearing-force and its direction rate between linkage and wobble-plate without clearance were deduced. Then the ratio of the direction rate to the force’s magnitude was obtained. The rule of the occurrence of contact loss between pairing elements in spatial wobble-plate mechanism was given according to the variation of the absolute ratio value. The conclusion is drawn that pairing elements will separate at specific angles of principal axis. This study may provide reference to the vibration and noise control of the torpedo wobble-plate engine, and to the dynamical optimization of torpedo wobble-plate engine with clearance.

Numerical Simulation on Flow and Heat Transfer Characteristics of Combustor

TANG Ling-hong, MA Xiao-li, SHI Hai-chao, ZHAO Wei-bing, Wan Rong-hua

2010, 18(4): 295-298. doi: 10.11993/j.issn.1673-1948.2010.04.013

[Abstract](1168) [PDF 387KB](670)

Abstract:
Addressing the faults on the hull wall of a combustor, such as deformation, crack, wrinkle and local over-heat under high-temperature gas, three-dimensional numerical simulations of flow and heat-transfer characteristics of the combustor are conducted via the standard k-ε model with standard wall function and DO radiation model. Results show that heat transfer performance of the half-ball bottom worsens because the reduction of the flow area in the combustor nozzles makes the velocity of gas flow sharply increase, and temperature is higher at some parts of the bottom. The highest temperature of cooling water in the cooling passage is lower than the saturation temperature corresponding to the cooling water pressure, the water-side pressure drop of the combustor depends primarily on the shape of the spiral passage, and the total pressure drop in the cooling passage is smaller than the allowable maximum value.

Influence of Tail Jet Temperature of Supercavitating Underwater Vehicle on Cavitation Configuration

DANG Jian-jun, CHEN Wei-hua, LIU Jian-zhao

2010, 18(4): 299-302. doi: 10.11993/j.issn.1673-1948.2010.04.014

[Abstract](1729) [PDF 599KB](674)

Abstract:
In order to meet the hydrodynamic conditions for supercaviating underwater vehicles moving stable, the cavity closing on a vehicle must have a particular configuration to balance the vehicle’s gravity and the moment suffered. In this study, the influence of tail jet intensity on the steady supercavitating flow was analyzed, and a numerical simulation of ventilated cavitation and tail jet flow field of a 2D underwater vehicle model was performed by using calculation fluid dynamics (CFD). Supercavitating flow was analyzed at different tail jet temperature when the attack angle of the vehicle model was zero degree. The law of influence of tail jet temperature on supercavition was achieved, which agree with experimental result.

Effect of Ship Motion on Water Entry Parameters of Torpedo

XU Qin-chao, LIAN Yong-qing, WANG Shu-zong

2010, 18(4): 303-307. doi: 10.11993/j.issn.1673-1948.2010.04.015

[Abstract](1582) [PDF 181KB](659)

Abstract:
Ship motion imposes clear effect on torpedo launching process. In order to analyze water entry parameters of a torpedo, the effect factors on water entry parameters are analyzed. A mathematical model of the parameters is established by comprehensively considering the effects of swing, speed, torpedo tube turning angle, and attitude of a ship in torpedo launching process on the water entry parameters. Simulations are conducted in different conditions, and the results show that the present model can really reflect torpedo launching process

Calculation and Analysis of Hit Spread for Straight Running Torpedo Salvo

XIA Pei-lun, LIU Yong, CHEN Zhi-peng

2010, 18(4): 308-311. doi: 10.11993/j.issn.1673-1948.2010.04.016

[Abstract](1621) [PDF 156KB](680)

Abstract:
Some issues concerning the calculation of hit spread (HS) for straight running torpedo (SUT) salvo are studied. HS is a very important torpedo fire parameter and guaranteeing that the attacked target does no t escape from two salvo torpedoes. Methods for calculating HS of SUT for various cases are given and analyzed, and the proportional relation between HS of SUT and tangent of the lead angle is discovered. An interesting phenomenon is observed that a reverse firing order o f torpedoes may actually become a forward firing order if the target with high speed is not long enough and the torpedoes are launched with longer time interval. In addition, the software Matlab 6. 5 is adopted to visually reveal the properties o f the HS calculation formulas.

Analysis on Parameters Influencing Intercept Probability of Anti-torpedo Torpedo

YOU Da-de, XU De-min

2010, 18(4): 312-315. doi: 10.11993/j.issn.1673-1948.2010.04.017

[Abstract](1621) [PDF 155KB](768)

Abstract:
To understand the major parameters which influence intercept probability of ananti-torpedo torpedo (ATT), we establish a torpedo trajectory model and a ship evasion model based on assumptive intercept state. According to the calculation results, we quantitatively analyze the effects of detection error, homing range, and homing sector angle on intercept probability of ATT. Simulation results indicate that the intercept probability of ATT can be effectively improved by raising locating accuracy of coming torpedo, and increasing homing range and homing sector angle of ATT.

Simulation of Rocket Assisted Torpedo Salvo Attack from a Two-Warship Formation

MEN Jin-zhu, ZHOU Ming, ZHENG Ya-bo

2010, 18(4): 316-320. doi: 10.11993/j.issn.1673-1948.2010.04.018

[Abstract](1573) [PDF 189KB](706)

Abstract:
According to the current tendency of anti-submarine warfare formation, we introduce three firing methods of rocket assisted torpedo salvo from a formation of two surface warships, establish three firing models and three salvo interval models of the three firing methods, and calculate the hit probabilities of the firing methods. Simulation results show that the hit probabilities of the three firing methods are all beyond 0.9 when the distance between the formation and the target is less than 38 km, the hit probability of the firing target’s advance position method reaches more than 0. 95 with in the firing range of the torpedo, and the hit probabilities of the firing target’s present position method and the firing target’s probable position method are less than 0.8 if the distance between the formation and target are larger than 46 km and 51 km, respectively.

2010 Vol. 18, No. 4

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