A review on solar still: a simple desalination technology to obtain potable water

Present review paper presents an overall summarised presentational view of the research work to be discussed on the solar still. The current review paper also includes the infused crisis and struggle for obtaining fresh water for drinking purpose and consumption for other household activities which are a result of the ecological imbalance that has prevailed and is in continuation for past many centuries. It also shows the various tested and applied techniques for freshwater production and their suitability in the usability context in the present scenario of the scarcity of clean water. The use of solar desalination technology is discussed elaborately for a broader consumption to be employed in the current and future works.     

Experimental study on control fins of a small flying vehicle using piezo-composite actuators

A camber morphing control fin design and an all-moving control fin design using piezo-composite unimorph actuators are presented in this paper. The control fin of a small flying object is usually actuated using a servo motor system with an electromagnetic motor. Much research has been conducted to solve the structural complexity of servo actuation systems to convert the rotation of a servo motor to a linear actuation motion. To simplify this structural complexity, several types of smart actuators have been developed, such as bimorph or unimorph actuators with piezoelectric material layers and shape memory alloy actuators. In this study, a camber morphing type control fin and an all-moving type control fin actuated using piezo-composite actuators are designed to evaluate their ability to simplify the structural complexity of the gear transmission and electromagnetic servo motor system or hydraulic actuator system. Within the skin of the control fin, a piezo-composite actuator is mounted and the other end inserted in a slot of the control fin. As the piezo-composite actuator is excited by an electric field, the pitch angle of the control fin is changed. Experimental testing for the pitch rotation angle of a control fin in a 450 V electric field showed the deflection angle of the camber morphing control fin was 1.4° and the rotational angle of the all-moving control fin was 5.4°, which is obtained from the rotation angle magnification linkage structural system.     

Heat spreading in a thin longitudinal fin

In view of the trend towards higher power densities in ever shrinking geometries, understanding heat spreading fundamentals is gaining importance. In this paper heat spreading in thin longitudinal geometries is considered. This geometry is of practical interest in one-dimensional Cartesian geometries. A characteristic length is derived and it is shown that this has physical significance for the distance that heat spreads, and for the total amount of heat cooled away. Furthermore, it is investigated when “thin” is a viable assumption. The use of the characteristic length is illustrated for the case of a line source cooling to a plate and for the case of the fins of a plate heatsink. The results are compared to numerical simulations. The work is an extension of the authors' earlier work on heat spreading in infinite longitudinal geometries and heat spreading in infinite and finite circular geometries.     

气缸散热片对压缩机温度场影响的试验研究

以传热学和空气动力学的研究成果为基础,应用正交法设计气缸散热片,并且对空压机以及气缸、气缸盖等温度进行了试验与测量;确认了不同的气缸散热片设计对压缩机的排气温度、气缸盖温度场、气缸温度场以及曲轴箱润滑油温度等各个部分温度的影响是各不相同的;该试验还证实了勃拉休斯关于附面层方程解的科学性。     

板翅式换热器中新型微凸翅片结构设计及性能分析

为提高翅片区域的换热效率、改善板翅式换热器的整体换热性能,提出了一种新型微凸翅片结构。基于结构参数多采样点处的热力学性能仿真结果构建近似模型,以翅片热功率最高为优化目标、压降为约束,使用序列二次规划法确定了微凸体结构参数（微凸高度、微凸夹角、微凸开口长度）的最优值;对微凸体排列间距、排列方式进行优化,确定了改进微凸翅片结构的具体参数值。通过对翅片流道内温度场、压力场分析,以及与相同尺寸的平直翅片的换热性能对比,验证了所提出的新型微凸翅片结构的有效性。     

基于同心环形缝隙流理论的纤维编织网增强混凝土抗渗性能研究

通过对压力水作用下纤维编织网增强混凝土(TRC)的渗透试验和扫描电镜(SEM)试验,探究不同水灰比、纤维单丝含量对TRC试件抗渗性能及内部细观结构的影响。研究表明,自由水在压力作用下沿着混凝土基体与纵向纤维束的界面进行定向迁移,TRC的抗渗性能随水灰比及纤维单丝含量增大而减弱。此外,SEM试验表明,混凝土基体与纤维束的界面存在环形裂隙,裂隙宽度随水灰比及纤维单丝含量增大而增大。基于同心环形缝隙流理论,建立压力水作用下TRC试件渗透率的计算公式,计算结果与试验值吻合较好。     

仿鱼柔性长鳍波动运动分析与建模

研究了弓鳍目鱼“尼罗河魔鬼”的柔性波动长背鳍.针对波动长鳍大的柔性变形特征,提出了由N根刚性鳍条依靠柔性薄膜连接组成的柔性波动长鳍简化模型;在分析长背鳍运动和流固耦合的基础上,建立了柔性波动长鳍的运动学模型;进而,从弹性薄壳理论出发,考虑柔性长鳍结构的几何非线性,并引入无矩薄壳理论的假定,建立了柔性长鳍波动的平衡方程.依据所建立的运动学模型和柔性长鳍波动的平衡方程,可以进一步解析柔性长鳍波动运动的动力学性能.     

CPU散热片冲孔复合模具设计中的废屑处理

在CPU散热片冷冲压成形中,为节省材料,提高效率,设计了用机械手传送零件的连续模,取代了传统方法的连续模。在提高经济效益的同时也带来了一些问题,其中冲孔落料工序中的废屑处理尤为显著。本文探讨了冲孔落料模具的设计方法,有效解决了废屑处理的问题。不仅使成形可以顺利进行,还实现了省时节约的目的,对业内设计人员有一定的借鉴作用。     

旋转对非圆形扰流柱排换热影响的数值模拟

对有非圆形叉排扰流柱排的旋转矩形通道的换热旋转效应进行了数值模拟。扰流柱排的几何参数为/=4,/=1.33,/=2.7。来流雷诺数=20000下,旋转数o=0～0.3时对三种不同形状(方形、钻石形和液滴形)的扰流柱旋转矩形通道的换热研究。结果表明:迎风面与背风面的平均数都随着o的增加而增大;钻石形扰流柱排通道的换热最强,其次为方形、液滴形;此外,研究发现随着旋转的增强,矩形通道端壁各段的换热变化呈现出不同的规律,进口区端壁的换热会增强,而扰流柱排区以及尾缘区的换热则先减后增。