深海AUV下潜过程浮力变化研究

由于深海AUV的潜深大,其下潜过程中温度、压力和盐度变化都较大,这些参数的变化会显著地造成下潜过程中的浮力的变化,从而极大地影响AUV航行性能.针对该问题,首先对影响浮力的主要因素进行了独立研究,得到了各因素和浮力变化之间的关系;然后将各因素的影响进行综合,并结合海上试验数据,得到了6000 m级AUV潜龙一号下潜深度和浮力变化的定量关系.研究结果表明:压力对浮力变化的影响最大,浮力随着压力增加呈线性增加;温度对浮力变化的影响(和初始下潜的水面温度有关)次之,且其关系是非线性的;盐度对浮力变化的影响最弱,且其对浮力变化的影响随着潜深的增加而减小.海上试验证明了分析结果的正确性,AUV配平效率得到有效提高.     

水下滑翔机垂直面运动优化控制

水下滑翔机是一种依靠水动力和净浮力驱动的新型水下机器人. 本文分析了滑翔机在垂直面滑翔时, 浮力变化和内置可动质量块位置变化对滑翔机运动状态的影响．针对滑翔机在潜浮切换时, 由于机翼受力不对称产生的无升力现象而导致的切换过程不稳定的问题, 采用两点边值的优化控制方法, 规划了内置质量块的位量, 以消除滑翔机在潜浮切换过程中各个时刻产生的不对称无升力现象．最后给出了滑翔机实际机械系统可接受的最优控制 方案. 仿真表明了这种优化方法的有效性.     

潜艇潜浮过程中均衡操纵的建模与仿真

该文通过分析艇体在潜浮过程中所受的力和力矩的变化,建立潜艇前浮运动的基本方程,计算出浮力差和力矩差：通过操舵与均衡水柜注排水进行行进间均衡,建立舵效模型和注排水模型;在对潜艇潜浮过程的模拟的基础上,对潜浮和均衡的操纵方法进行仿真研究,即在潜艇有总纵倾和无纵倾定深控制时,通过操随航速变化首尾舵平衡角进行控制,同时给出补充均衡的实例;结果表明所建立的模型是正确有效的。     

支承舱减振性能分析

支承舱是运载火箭与航天器之间的重要连接结构,支承舱的振动特性是力学环境设计需要考虑的因素之一.本文从振动环境控制的角度进行支承舱结构动力学分析,阐述了一种基于支承舱振动特性研究的改善航天器力学环境的方法.在有限元建模过程中,引入了材料级性能试验.计算并比较了不同材料支承舱结构对航天器振动环境的作用,比较了连接面形式对振动环境的影响.基于分析结果给出了进一步研究的建议.     

三叶渐开线罗茨风机转子数值分析与优化

为了获得三叶渐开线罗茨风机基圆半径变化对风机性能的影响关系,首 先从几何原理角度,分析了渐开线基圆变化对风机转子啮合渐开线的影响,给出了符合啮合 条件的渐开线基圆半径变化范围,及不同基圆半径对转子面积利用率系数的影响情况。在此 基础上利用数值分析方法,对同种叶型不同基圆半径时的风机转子流场进行数值计算,运用 动网格技术分析了风机内部的压力场、涡的强度变化和进气口质量流量变化情况。模拟结果 表明：同种叶型渐开线基圆半径增加,能够削弱涡的强度和速度,增加进气口质量流量,提 高风机效率,因此风机生产企业设计时应选择较大的渐开线基圆半径。     

平孔喷嘴内柱塞流判定模拟分析

平孔喷嘴作为被广泛应用的雾化设备之一,其内部流型对雾化效果具有至关重要的影响。而目前对喷嘴内流型的判定方法还并不统一。本文建立了喷嘴内流型变化判定方法的数学模型,并利用模型喷嘴长度与直径比(L/d)、喷嘴入口倒角半径与直径比(r/d)和操作压力对流型的影响规律进行了模拟分析。结果表明:L/d对喷嘴内流型有一定的影响,L/d越大,越不易发生柱塞流;r/d对喷嘴内空穴区的强度影响显著,r/d越大,空化强度越低,越不易发生柱塞流,但喷嘴r/d大于0.05时,柱塞流依然可以发生;喷射压力对喷嘴内流型变化以及流量系数影响显著,流量系数与喷嘴内流型有一定的对应关系。应用本文的研究成果,可以通过合理地设计喷嘴结构和操作条件,使得喷嘴内流型始终处于空穴流区间,以达到强化雾化效果的目的。     

一种基于经典层合板理论的碳纤维深海机器人电子舱的设计方法

为满足深海领域商业开发对高强度电子舱的轻量化需求,文章提出采用碳纤维复合材料筒体与金属端盖组合设计深海机器人的电子舱,并基于经典层合板理论提出一种简化的电子舱承压结构壁厚尺寸设计方法。该设计方法简化了金属端盖内的应力分布和碳纤维复合材料堆叠的理论模型,从而能够快速地给出设计推荐数值;且在所给出的推荐数值下,碳纤维舱体重量比铝合金、钛合金舱体均具有显著优势,较铝合金的轻70%,较钛合金的轻20%。第四强度理论和传统层合板理论被分别用于逐层校核该方法给出的电子舱设计强度,结果显示金属端盖的安全系数为0.866,所设计的3 000 m和6 000 m两种级别复合材料筒体安全系数分别达到0.56和0.66,均小于1;有限元计算也被用于校核电子舱的设计强度,结果表明,3 000 m环境和6 000 m环境对应的铝合金/钛合金端盖和碳纤维筒体应力极限均未超过对应材料的许用极限,验证了该设计方法的有效性。     

基于装配的液舱三维建模与仿真

船体结构复杂,液舱及其主要构件占实际舱容约99%的型舱容.由于实际使用中发现近似计算存在的误差较大,准确地建立液舱模型就成为准确计算舱容的关键和研究热点.本文根据液舱舱体和构件特征,采用Top-Down设计方法和基于wAVE的全相关产品设计技术,通过建立引用集对液舱舱体和构件进行参数化建模,实现了液舱在多种浮态下的三维建模与仿真,为舱容计量提供了准确的三维模型.     

结构强度自动化计算平台StrenBox——方法和实践

为提高结构强度计算效率,增强飞机等结构强度计算工作的协同性,促进强度设计知识和经验的传承,基于CAESAM开发环境构建StrenBox结构强度自动化计算软件平台. 就该平台的基本理论和方法进行阐释,并以1个飞机结构的典型舱段结构为例进行实际应用的演示和说明. 最后,根据飞机等结构强度设计和研究的当前状态,对结构强度自动化计算软件平台的进一步工作进行展望.     

全海深ARV浮力配平计算方法

全海深ARV(自主遥控水下机器人)下潜至马里亚纳海沟,机器人工作环境温度降低、海水压力增大,会引起载体结构、补偿油体积变化.根据深渊海水密度、重力加速度和机器人体积的变化,计算得到机器人浮力状态的变化量,从而计算机器人浮力配平.通过公式推导并结合"海斗号"ARV深潜数据和补偿油压缩实验数据,得到全海深ARV浮力配平计算方法.其主要包括海水密度测算、马里亚纳海沟重力加速度测算、机器人结构和补偿油排水体积变化测算.计算得出在11000 m深度实现浮力配平所需的压载为8.9 kg.完成"海斗号"ARV浮力配平,保障机器人深渊工作环境浮力与重力匹配,成功进行了多次马里亚纳海沟万米深潜.本文方法为全海深水下机器人浮力配平提供了理论计算依据.     

The Data Analyses of a Vertical Storage Tank Using Finite Element SOFT Computing

With the rapid development of the petrochemical industry, the number of largescale oil storage tanks has increased significantly, and many storage tanks are located in potential seismic regions. It is very necessary to analyze seismic response of oil storage tanks since their damage in an earthquake can lead to serious disasters and losses. In this paper, three models of vertical cylindrical oil storage tank in different sizes, which are commonly used in practical engineering are established. The dynamic characteristics, sloshing wave height and hydrodynamic pressure of the oil tank considering the liquid-structure coupling effect are analyzed by using ADINA finite element software, which are compared with the result of the standard method. The close numerical values of both results have verified the correctness and reliability of finite element model. The analytic results show that liquid sloshing wave height is basically in direct proportion to ground motion peak acceleration, the standard method of portion sloshing wave height calculation is not conservative. The hydrodynamic pressure generated by liquid sloshing caused by ground motion is not negligible compared with the hydrostatic pressure. The tank radius and oil height have a significant effect on the numerical value of hydrodynamic pressure. The ratio of the hydrodynamic pressure and hydrostatic pressure, which is named hydraulic pressure increase coefficients, is related to the height, which given by the GB 50341-2014 code in China have a high reliability. The seismic performances of tank wall near the bottom needs to be enhanced and improved in the seismic design of the oil tank.     

Optimal shapes of cylindrical concrete water tanks

The optimal wall shapes of circular cylindrical concrete water tanks are treated herein. The tanks have piecewise linearly tapered wall thicknesses. The internal radius and height of the tank are maintained constant while the thickness of the wall is varied along the axis so that the critical bending and hoop stresses attain values as close as possible to their allowable values. For the analysis a procedure which combines the Runge-Kutta method of solution of ordinary differential equations with a numerical minimization method is used. This procedure is then imbedded into a minimization routine to deal with the design problems. The results of the study show that the major saving in material is achieved by one slope itself. While two slopes improve the saving in material for some tanks, it does not seem reasonable to increase the number of slopes beyond two.     

液体晃动条件下飞艇水箱动力响应仿真分析

为了增加重载飞艇的载重能力,在满足结构强度要求下飞艇上的贮水水箱需要采用薄壁结构、轻质材料等方法来减轻重量。水箱在空中受到风载荷或其他载荷的作用,会导致水箱中的液体发生晃动,水箱在液体晃动和外部载荷共同作用下,可能会遭到破坏。考虑流固耦合作用对水箱结构的影响,分别从液体小幅晃动和大幅晃动两种情况对水箱动力响应进行研究。对于大幅晃动的情况,以试验所得风载荷加速度函数作为激励,利用计算流体动力学（CFD）方法进行仿真分析。分析结果表明,小幅晃动条件下,即使水箱发生共振,其结构也不会遭到破坏;大幅晃动条件下,1.3 mm以下壁厚钢材料水箱和2.1 mm以下壁厚铝合金材料水箱结构会遭到破坏。该分析结果可为水箱部分设计参数的确定提供参考依据。     

基于MFC的油罐设计抗震验算软件开发

目前各设计院在铁路油罐设计中多采用标准图,通常都不进行强度及抗震等要求的验算.在抗震设防烈度要求较高地区,标准油罐的罐底环形边缘板厚度和各圈罐壁有效壁厚往往达不到要求.通过开发适用于铁路机务设计中的油罐抗震验算软件,不但可以提高机务设计效率,还能保证设计储罐的安全可靠性.     

红外目标与背景的真实感合成

目标与地面背景的真实感红外图像合成是红外场景生成和实现其虚拟实时漫游的关键技术。文中从传热学原理出发，综合考虑各种环境因素的影响，建立起地面目标（如坦克）的热传导模型，绘制出坦克在各种状态下的红外图像。根据计算出的坦克和地面接触后达到热平衡时的温度场分布，绘制出真实感较强的坦克与背景的红外合成图像。利用三维差分法计算并绘制出坦克离去后留下的“红外阴影”效果，即地面因原有目标强烈辐射而留下的高于周围区域的温度场分析，并绘制出坦克驶离后不同时刻地面背景灰度及彩色的红外图像，为倒推某时刻之前红外目标的存在提供了依据。     

动车水箱安装座的强度计算和结构改进

为使动车上的水箱安装座具备足够的强度,以保证连接的可靠性,利用三维实体建模并用Hyper Works对水箱安装座进行有限元计算;依据EN 12663:2010标准对水箱安装座进行强度校核并针对不满足强度要求的部分进行结构改进.结果表明:改进后的模型设计能够满足EN 12663:2010的标准;CAE软件的应用为水箱安装座的结构设计提供参考.     

Computer aided design of post-tensioned concrete reservoirs

A computer method based on the classical shell and plate theories is presented for the elastic analysis of cylindrical water tanks subjected to axisymmetrical loading and post-tensioning loads. A spherical dome or circular plate roof, cylindrical container, top and bottom ring beams together with a circular plate foundation are considered as possible components of a water tank in the flexibility formulation. Classical shell, plate, and ring beam theories are used to obtain flexibility coefficients. A computer program has been developed based on this formulation and successfully used in the design of post-tensioned concrete water tanks with diameters of 80 m built in Saudi Arabia.     

Determining the optimal number of duplicated process tanks in a single-hoist circuit board production line

In a circuit board production line, each circuit board carrier must be soaked in a sequence of process tanks and the soak time at each process tank must be within a prespecified time interval. Processes with long minimum soak times can create severe bottlenecks. It is common practice to add duplicates of the tanks for these processes to improve the throughput of the line. This paper studies the problem of determining the optimal number of duplicated process tanks to be used in each process that maximizes the throughput for a given tank configuration of a single-hoist circuit board production line. The problem is formulated as a mixed integer program. The properties of the optimal solution are derived. On the basis of these properties, an algorithm is developed to solve the problem optimally. Computational experience with the benchmark problems is discussed.     

Thermal degradation of the concrete roof of high-level waste storage tank

The DOE's high-level waste storage tank (HLWST) sites consist of single- and double-shell concrete tanks covered with soil overburden. Due to the high temperature (212 °F and above) of the liquid-filled waste, the concrete walls and domed roofs are expected to endure thermal degradation which, in turn, may lead to cracking of the concrete. A remote video camera inspection of one such HLWST indicated some ‘irregularities’ on the inner surface of the tank dome. A finite element model using ADINA was developed to simulate the field conditions including concrete strength deterioration. The model was first validated against the results obtained from tests conducted on a 1/10th-scale model. The analysis was then extended to study the actual field behavior. The results confirmed the overall structural integrity of the tank by considering the global response of the tank and a detailed analysis of likely crack patterns in the dome area. The paper describes the complexities in validating the scale model as well as prototype response.     

油罐常用安全附件的维护与保养

目前油田使用的各式储罐基本上可分为钢制拱顶地上油罐和单盘式外浮顶储油罐两大类。这些储罐在日常运行和维护保养中的操作比较繁琐,带来的安全隐患也比较多,尤其是油罐安全附件的安全运行、检查、维护与保养,都关系到油区的日常安全生产。文章从日常运行管理方面,探讨了日常使用的油罐安全附件的日常运行、安检、维护和保养方法。