船舶主机气囊隔振系统对中控制的响应特性分析及算法研究

分析了气囊隔振装置的压力变化对主机对中姿态的影响,认为主机姿态控制的响应计算可进行线性化处理,并给出了满足线性计算精度要求的压力变化范围。基于分析结果,提出了一种的优化控制算法,将气囊压力分布与对中姿态同时作为控制目标。在试验台架上验证了理论分析的正确性,控制算法使气囊压力与对中姿态两个指标均能快速收敛到精度范围,具有较高的控制精度。     

船舶主机气囊隔振技术对中控制策略研究

针对气囊隔振器应用于船舶主机低频隔振面临的如何保证轴系对中精度技术难题,开展其对中控制策略研究。建立了对中状态响应特性分析模型,为解决该分析模型计算输入参数难以精确获取的问题,提出一种伪灵敏度分析方法。基于控制对象伪灵敏度矩阵,研究出可行的对中控制策略。应用该控制策略可使得控制系统在多目标、强耦合条件下,以良好的动态工作性能实现高精度对中控制,并保持装置承载力的均匀分配。     

主机气囊隔振装置对中姿态控制算法研究

将气囊隔振装置应用于船舶主机能够大幅衰减振动向船体基座的传递,但同时也增大了主机与轴系对中控制的难度。在实现对中误差在线监测的基础上,根据气囊隔振装置的特点,提出一种对中调整最优控制算法,通过对气囊充放气调整,使主机恢复到对中状态。试验表明该控制算法能在快速收敛到对中精度的同时,实现载荷的优化分布。     

连续线性混沌隔振装置设计与研究

根据混沌隔振原理设计出连续线性混沌隔振装置,该装置能够产生强非线性,其线性部分、非线性部分与模型几何尺寸相对应,并且两者完全区分开。在实验中两者均易于调节,这大大增加了该装置在工程中的应用前景。并利用数值计算对特定参数下的隔振装置在简谐激励力作用下的运动特性进行分析,分析结果表明该装置能够产生混沌运动,且具有很好的隔离线谱的能力。     

气囊浮筏隔振装置姿态控制问题

将气囊隔振器应用于浮筏隔振装置可显著提高低频隔振效果,但隔振元件的三相低频大位移也将带来三相动态平衡欠佳的实际问题,其中一个技术难点在于如何保持筏架姿态平衡。分析引起筏架姿态变化的各类扰动力特点及其影响;研究通过调整气囊压力保持筏架姿态平衡的可行性。结果表明,船体摇摆、装置负载变化及气囊漏气是影响筏架姿态平衡的主要扰动因素,气囊浮筏隔振装置可以通过气压的调整,在扰动力的影响下保持筏架姿态平衡。     

船舶主机气囊隔振系统动态特性分析

提出了将气囊隔振器应用于船舶主机隔振，介绍了该隔振装置的特性，并进行了动力学分析。分析表明，气囊隔振系统能够大幅度减小主机激振力向船体基座的传递。在其他条件不变时，系统具有定常频率特性，各气囊压力的分布对系统固有频率、力传递特性没有影响，而对主机输出端的位移有一定影响，应该通过优化设计使联轴节的振动最小。     

气囊隔振装置压力分布优化控制研究

首先对气囊隔振装置中气囊的压力分布进行了分析,然后以气囊压力分布方差最小为约束条件,计算出各气囊压力的比例因子,并运用比例控制充气策略,在确保气囊隔振装置高度的高精度控制前提下,实现了隔振系统中各气囊的压力优化分布。     

主动隔振与水下声辐射控制的实验研究

建立一个包括有机玻璃水箱和主动隔振器的实验系统,研究主动隔振对降低结构振动及其声辐射的有效性。实验模型的建立是基于流固耦合系统的有限元分析和局部模态测试,通过数值分析确定辐射面的振动模态以及辐射声场分布。扰动源的干扰频率接近辐射面固有频率,在水中形成共振状态下的辐射声场。扰动源采用四点主动隔离,四个电磁作动器同时控制并采用自适应对消算法,抑制扰动源周期性干扰引起的振动。实验结果表明主动隔振能够明显降低平板的辐射声压。     

基于磁流变悬置的动力装置垂向隔振控制与试验研究

悬置阻尼宽频可控对动力装置实现积极隔振具有重要意义。分析了基于挤压模式的磁流变半主动悬置工作原理和阻尼特性,在建立动力装置垂向隔振模型的基础上,设计出模糊自适应隔振控制器,用量化、比例因子自调整算法降低不同工况下动力装置垂向激励力的传递;给出了一种改进的天棚控制算法,通过抑制动力装置振动来降低能量传递。设计出动力装置隔振台架试验系统,在不同工况下进行了隔振对比试验。结果表明,在动力装置处于中低转速时,可控磁流变悬置能在宽频范围内把力绝对传递率抑制到25%内,隔振效果优于橡胶悬置;而磁流变悬置垂向隔振方法中,兼顾振动传递率和激励频率的模糊自适应控制,优于通过抑制动力装置自身振动来隔振的天棚控制。     

基于现场监测的海洋平台冰振控制效果评价

渤海辽东湾的ＪＺ２０－２ＮＷ 平台采用甲板阻尼隔振技术降低平台的冰激振动问题。根据海洋平台冰激振动的特点,设计现场监测系统,检验阻尼隔振系统的减振效果。对平台隔振的上下两层甲板的加速度和相对位移响应进行监测,并对实测数据进行对比分析。监测结果表明,上层甲板的振动强度相比下层甲板有所减弱,阻尼隔振装置起到控制上层甲板振动的效果。但是上下甲板的振动频率和相位无差别,说明减振装置未产生最理想的减振效果。同时对有无阻尼隔振装置结构的阻尼比进行提取,表明相对位移越大,上下甲板的阻尼比越大。减振后上下甲板的阻尼比都有所增加,结构振动耗能增加。应用实践表明,阻尼隔振技术是一种有效的海洋平台冰激振动减振措施,但仍有许多地方需要完善。     

主机对中姿态参数的近似算法

利用3个非共线设置的特征光标和单个CCD相机来获取空间物体的三维信息,采用广义欧拉角（布利恩角）来描述主机的对中姿态。基于小孔成像,建立主机与轴系之间的简化数学模型,推导了对中姿态参数的一种新的近似解析算法,建立了主机对中姿态方程,并叙述了姿态方程在主机对中姿态控制中的作用。最后,对该近似算法的误差进行仿真研究。     

Six-Degrees-of-Freedom Alignment of Two-Dimensional Array Components by Use of Off-Axis Linear Fresnel Zone Plates

A novel six-degrees-of-freedom (six-DOFs) alignment technique for assembling two-dimensional array components is presented. The technique uses off-axis linear Fresnel zone plates on one component that are combined with alignment targets on the other. The technique is compact and sensitive to all six DOFs; it was used to package an array of microlenses with a 32 x 32 array of GaAs multiple-quantum-well modulators flip-chip bonded to a 9 mm x 9 mm complementary-metal-oxide-semiconductor chip. By use of interference fringes to control the tilt misalignment, the worst-case misalignment of the microlenses relative to the chip is calculated to be as follows: lateral = 3.0 mum, rotational = 0.023 degrees , longitudinal = 13 mum, and tilt = 0.022 degrees . We also propose alternative implementations of the technique, including one that uses on-chip photodetectors to automate this six-DOF alignment technique.     

关于客车空调压缩机减振问题的思考

对一款客车空调压缩机支架减振设计的失误进行分析。研究结果表明,客车空调系统中压缩机部位的振动主要来自2个方面：发动机振动通过皮带传递到压缩机;压缩机运转过程中自身产生的振动。皮带传递的振动可以通过减振弹簧吸收,压缩机自身产生的振动可以通过安装的橡胶减振块吸收。     

Failure analysis of an aero engine ball bearing

An aero engine failed due to the misalignment of the ball bearing fitted on the main shaft of the engine. The aero engine incorporates two independent compressors: a six-stage axial flow low-pressure compressor and a nine-stage axial flow high-pressure compressor. The bearing under consideration is a high-pressure-location bearing and is fitted at the rear of the nine-stage compressor. It was supposed to operate for at least 5000 h but failed catastrophically after 1300 h of operation and rendered the engine unserviceable. Unusually high stresses caused by misalignment and uneven axial loading resulted in the generation of fatigue crack(s) in the inner race. When the crack reached the critical size, the collar of the race fractured, causing subsequent damage. The cage also failed due to excessive stresses in the axial direction, and its material was smeared on the steel balls and the outer race.     

无油干螺杆空压机的日常维护

分析无油干螺杆空压机主机卡死的原因,通过用干燥氮气吹扫主机及管道,杜绝了主机腔和管道内锈蚀物进入主机造成其卡死的现象发生;采取改进的维护措施后,有效地延长了空压机电器设备的使用寿命,为后续生产的正常进行提供气体保证。     

陀螺安装误差影响视轴稳定平台精度的机理研究

针对陀螺安装误差影响视轴稳定平台精度的问题,深入研究了其影响的作用机理及程度.以两轴稳定平台为具体对象,应用PIOGRAM图方法,讨论了安装误差对陀螺敏感量的运动学影响.并对陀螺安装误差影响系统精度以某实际模型为例进行了仿真分析,得出了其对稳定精度影响更为具体的解释.这对陀螺安装误差的标定、机构设计中安装面精度的取定以及误差分配等都具有参考作用.     

High-performance lift augmentation dynamic seals for turbine bearing compartments

Conventional bearing shaft seal systems used in gas turbine engines are often limited to a sliding velocity of about 100 m/s, differential pressure of 3 bar, gas temperature of 300°C and a seal life less than 8000 h. Advanced engines will require bearing shaft seal systems to operate up to sliding velocity of 200 m/s, differential pressure of 6 bar, gas temperature of 500°C and seal life in excess of 30?000 hours. For seals operating in these advanced conditions, a design with no rubbing contact will be required to achieve long life and reliability. A good validated approach is the use of a gas lift augmentation seal. The design objective for a seal of this type is to have the faces of the seal seek an equilibrium position to avoid any contact. The gap must be small enough to ensure a minimal air leakage, but it must be large enough to limit power dissipation, due to shear in the gas film, and face deformation by shaft displacement, misalignment and vibration. Dynamic seals for a bearing compartment have the following main functions: provide static and dynamic sealing in order to prevent oil leakage from the bearing oil compartment to the air compartment and consequently no oil smell pollution by the use of bleed air; control air leakage to the bearing oil compartment in order to improve performance of the engine and to reduce oil consumption; reduce volume of the oil tank and lubrication system and hence provide weight reduction; to operate in extreme conditions of temperature and with normal and reverse pressure; and reduce the mean time between overhaul (MTBO) and have a very long life. Techspace Aero and Burgmann have carried out design, development and testing of lift augmentation carbon seals and demonstrated that high life and performance levels of these seals are possible in a gas turbine engine environment.