Dynamic Response Analysis of Semi-Submersible Floating Wind Turbine with Different Wave Conditions

To address the problem of poor wave resistance of existing offshore floating wind turbines,a new type of semisubmersible platform with truncated-cone-type upper pontoons is proposed by combining the characteristics of offshore wind turbine semi-submersible floating platforms.Based on the coupled hydrodynamic,aerodynamic,and mooring force physical fields of FAST,the surge,heave,pitch,and yaw motions responses of the floating wind turbine under different wave heights and periods are obtained,and the mooring line tension responses are also obtained;and compare the dynamic response of the new semi-submersible platform with the OC4-DeepCwind platformat six degrees of freedom.The results show that different wave conditions have obvious effects on the heave and pitch motions of the new floating wind turbine,and fewer effects on the surge and yaw motions;the tensegrity response of the mooring system is more affected by the wave conditions;compared with the OC4-DeepCwind floating wind turbine,the pitch and roll response of the new floating wind turbine has been significantly reduced and has good stability.

Mechanistic Drifting Forecast Model for A Small Semi-Submersible Drifter Under Tide–Wind–Wave Conditions

Understanding the drifting motion of a small semi-submersible drifter is of vital importance regarding monitoring surface currents and the floating pollutants in coastal regions. This work addresses this issue by establishing a mechanistic drifting forecast model based on kinetic analysis. Taking tide–wind–wave into consideration, the forecast model is validated against in situ drifting experiment in the Radial Sand Ridges. Model results show good performance with respect to the measured drifting features, characterized by migrating back and forth twice a day with daily downwind displacements. Trajectory models are used to evaluate the influence of the individual hydrodynamic forcing. The tidal current is the fundamental dynamic condition in the Radial Sand Ridges and has the greatest impact on the drifting distance. However, it loses its leading position in the field of the daily displacement of the used drifter. The simulations reveal that different hydrodynamic forces dominate the daily displacement of the used drifter at different wind scales. The wave-induced mass transport has the greatest influence on the daily displacement at Beaufort wind scale 5–6; while wind drag contributes mostly at wind scale 2–4.

基于NX/WAVE的空调分体机逆向设计

以空调分体机的逆向设计为例,介绍了通过三坐标测量机进行接触式数据采集,应用NX/WAVE技术和自上而下的装配建模方法,多人并行地进行各零件的逆向设计,快速建立了空调分体机的3D数字模型。以此模型进行模具制造,企业可避免从国外进口模具,既节省成本,又可保证产品的质量。

某型号直升机超短波电台电磁干扰问题研究

【目的】对某型号直升机在试飞过程中因超短波电台干扰空调工作而产生的故障进行分析,为解决直升机电磁兼容问题提供建议。【方法】通过对相关系统原理及故障机理进行分析,以故障树形式来梳理故障产生的原因,并在直升机上逐一进行验证,最终定位故障点,并采取有效的排故措施。【结果】可从根本上解决该型机超短波电台干扰空调工作的共性问题,并根据电磁兼容性问题发生的基本原因,对三个基本解决方法进行优化。【结论】在试飞过程中,直升机上常见的故障与电磁干扰有关,而在生产制造过程中对直升机进行电磁兼容试验是十分重要的,充分的试验可提前发现电磁兼容性问题,并在地面解决,从而避免后续试飞过程中出现故障,保证试飞任务的顺利完成,提高直升机生产质量。

智能型变频空调在北京新机场线的应用

智能化控制、节能、舒适性已经成为轨道车辆空调系统的发展方向。北京地铁大兴机场线被誉为“北京市轨道交通建设新里程碑”,该线路采用世界最高等级、具有完全自主知识产权的全自动驾驶系统,不仅可实现无人驾驶,还可实现列车自动唤醒、自检、运行、休眠等全过程。文章介绍了北京新机场线轨道车辆所使用的智能型变频空调系统方案。该方案集成变频空调系统达成对客室内的精确温控,降低温度波动;采用压力波保护装置隔绝车外的气压波动,有效避免乘客出现耳部不适感,提升乘客乘车体验;配置低温等离子空气净化装置,利用低温等离子体对送入车内的空气进行杀菌、消毒,并去除其中异味,进一步实现了客室内部舒适性的提升。同时,压缩机的变频控制精确匹配车内热负荷的变化,并对电能高效利用,降低了空调系统的运营能耗以及成本。

变频空调的性能研究

变频空调以其节约、舒适、噪音小等特点吸引了众多的消费者。然而,其中的变频器会产生高频波与高周波,造成环境污染,本文就其性能特点进行了探讨。

空调室外机减振垫对振动和噪声影响的研究

用有限元法建立家用空调器室外机及压缩机制冷系统的动态分析模型,使用ANSYS软件做结构模态分析,求出使用不同刚度减振垫时配管对整个结构振动的影响,系统的固有频率和振型变化情况,得出最适合的橡胶垫刚度,使得压缩机结构振动减小。实验测量不同刚度减振垫对应的振动和噪声,绘制振动速度图,进行频谱分析,并通过采取合适的减振、降噪预测措施,使设计具有科学性、可行性和经济性。

基于机电波传播理论的柔性功率调节器稳定控制方法实验研究

柔性功率调节器(FPC)是一种集成了飞轮储能技术和双馈电机技术两者优点的新型FACTS装置。而机电波传播理论是一种分析和研究电力系统有功功率振荡的新思路。本文将机电波理论应用于提高实际电力系统稳定性,分析了单机系统中机电波传播特性,提出了基于该理论的FPC稳定控制方法,为所研制的380V/4kW FPC样机设计了稳定控制器。样机动模实验结果表明,FPC能够有效地提高系统稳定性,从而验证了所提方法的可行性和FPC技术的实用性。

一种超宽带中功率MPM的设计

介绍了一种超宽带中功率微波功率模块(MPM)的设计方法,主要内容包括MPM的系统构成和系统集成设计,重点阐述了前级固态驱动放大器以及后级行波管放大器外围集成电源的设计方法,针对MPM要求的小体积、高功率密度带来的散热问题作了细致的分析,提出了工程设计中的解决方法,并以此为基础,研制出了一种较为通用的100 W/6-18 GHz微波功率模块。

Analysis on the applicability of VLFS for China

With the advantages on rapid construction,no limitation of extent,less influence on environment, the VLFS has been turned into the focus of coastal and offshore engineering studying.As the platform,VLFS was built as airport,huge oil house etc,and would play the role of ocean economics,politics and military.The restrictive condition of VLFS is strong wave by monsoon,seismic,serious bomb etc.The floating breakwater should be put forward to shelter VLFS.The analysis of wave condition including typhoon route,archipelago and water depth is performed in this paper.The advantage and disadvantage are compared between VLFS and the marine structure from land.

钟形地形动力抬升和重力波传播与地形云和降水形成关系研究

地形云和降水过程在区域水循环、水资源、生态环境及气候变化中具有十分重要的作用。本文利用中尺度数值模式WRF数值模拟试验,以及通过引入表示大气层流速度、层结稳定度和地形特征的关系参数——湿Froude数(Fw),研究了北京2009年5月1日湿条件不稳定大气层结下,地形云和降水形成过程与地形动力抬升和地形重力波传播之间的关系及形成机理。研究表明,在地形最大高度2km、半宽10km的条件下,层流速度从2.5m/s逐步增加到25m/s时,对应的湿Fw数从0.19增加到1.81。当Fw≤1时,地形的阻挡起主要作用,由地形抬升形成的地形云主要产生在迎风坡一侧。地形重力波主要产生在迎风坡,并向上游传播,先形成层状云,最后演变为准稳定浅对流波状云。最大降水主要发生在紧靠山顶的迎风坡一侧,但当Fw很小时,地形云不产生降水。当Fw>1时,地形抬升形成的云主要发生在山顶附近,而地形重力波主要形成在背风坡,并向下游方向传播,形成准稳定波状云。最大降水主要产生在紧靠山顶的背风坡一侧。另外,在弱湿条件不稳定大气层流下,地形降水主要由地形动力抬升造成的暖云微物理过程产生,地形重力波形成的波状云几乎不产生降水。

空调管路系统的有限元分析及优化设计

针对设计好的空调管路系统振动较大问题,运用Hyper Mesh软件将设计好的空调管路模型划分成高质量的六面体网格。再将划分好的网格模型导入Ansys中进行模态分析,分析计算出前10阶的固有频率和振型。发现1阶固有频率在工作频率附近,分析该阶固有频率的振型并据此提出管路改进的设计方案,使空调管路系统固有频率远离工作频率,避免产生共振。最后对改进前后的结构进行实验对比,得到改进后的结构振幅减小90%的结果。实践表明在空调减振过程中应用Ansys等有限元技术辅助分析很好地提高了效率和准确性。

Ku波段微波无线输能系统技术研究

微波无线输能是未来能量传输的一种重要手段,在太阳能电站、孤岛输电、无人机供电、能源卫星等军民用领域有广泛应用前景。根据能源卫星无线传能这一应用需求,基于高效率真空功率器件,文中将载波频率拓展到Ku波段,高压电源采用单级谐振变化技术,显著降低了变换器开关损耗;微波源为高效率行波管,采用螺距动态速度渐变再同步技术和多级降压收集极技术,大幅度提高了互作用和收集效率;微波整流采用肖特基二极管,并进行多路合成,降低了插入损耗,优化了整流效率。据此搭建了Ku波段高效率远距离微波无线输能系统,经测试,在载波频率12.5 GHz、传输距离25 m条件下,微波发射功率150 W,市电到直流(AC-DC)总转换效率达5.6%。

家用空调室外机配管动力学分析及优化设计

利用有限元仿真技术对某型家用空调室外机管路进行了动力学分析,掌握了原始管路的模态及谐响应结果并根据结果对管路进行优化,从仿真及试验角度对优化管路进行了分析及试验验证,结果表明:采用仿真技术对室外机管路进行优化设计是可行的,取消管路用于减震的阻尼块、橡胶块,提高了管路质量一致性及可靠性。

The effects of bonding conditions on the propagation of acoustic waves along a cased borehole

Based on the wave equations in cylindrically layered structures and boundary conditions, the frequency equation for axisymmetric guided waves and the expression for sound fields in a cased borehole excited by a monopole or multipole source have been derived. The synthetic full waveforms excited by the monopole and dipole source are simulated using a real axis integration and FFT method. According to the axisymmetric guided wave modes, the synthetic full waveforms and the effects of the interface conditions on the sound field in a cased borehole have been analyzed and studied respectively. Numerical results indicate that it may be difficult to distinguish well bonded, poorly bonded or unbonded intermediate layer between the steel pipe and formation if only using a monopole source or dipole source. To properly estimate the case boundary conditions, a combination of monopole source logging with dipole source logging is suggested.

毫米波雷达在空调器上的应用研究

目前,在空调器上采用较多的环境感知传感器主要是红外传感器、摄像头,这类光学设备无法有效的保护隐私,用户易有排斥心理,且摄像头受光线影响大,无法全天候工作,不是最佳的环境感知传感器选择。不同于这些传感器,毫米波得益于电磁波的物理特性,可以实现高精度的距离、角度、速度的测量和目标的识别和追踪,可以几乎不受影响地在黑暗、强光、雾霾雨雪等恶劣天气工作,且没有隐私泄露的问题,非常合适作为环境感知传感器使用。通过对60 GHz毫米波雷达在空调器上的应用研究,证实其数据可靠性高,可作进一步深入研究。

家用柜式空调钣金件减振降噪设计研究

基于CAE仿真分析技术对某型家用柜式空调钣金件动力学分析,结合噪声诊断分析结果,通过改变加强筋的设计参数实现对钣金件的模态振型优化,提升了钣金件的减振降噪性能。试验结果表明:经优化后,空调钣金件噪声振动辐射降低,空调内机声品质明显改善。

An application of radiation boundary condition to scattering problem of acoustic waves in fluids

A numerical method of solving acoustic wave scattering pnblem in fluids is described. Radiation boundary condition (RBC) obtained by factorization method of Helmholtz equation is applied to transforming the exterior boundary value problem in unbounded region into one in a finite region. Combined with RBC and scatterer surface boundary condition, Helmholtz equation is solved numerically by the finite difference method. Computational results for sphere and prolate spheroidal scatterers are in excellent agreement with eigenfunction solutions and much better than the results of OSRC method.

微窗波纹片换热器在热泵空调上的研究

本文通过CFD仿真设计优化了一款微窗波纹片换热器,该换热器经过验证,证明其在热泵空调器上具有应用价值。

微波功率模块——新型功率电子器件

微波功率模块MPM是上个世纪末提出的一种全新的电子器件,具有高效率、高增益、重量轻、体积小等优点,是功率放大技术的重大突破,已成为构建各种军用电子装备和民用系统的基本单元,在雷达、电子对抗和通讯等领域已得到应用,是未来武器装备核心电子器件。文中从MPM概念的提出入手,首先介绍了MPM基本组成与特点,然后对MPM的可靠性以及技术难点进行了分析,并展望了MPM的应用和发展。