为研究表面形貌对表面润湿性和抗附着性能的影响,采用激光刻蚀技术制备点阵微结构和仿生贝壳表面网格微结构,将SiO2纳米粒子涂覆在微结构上制备微纳结构。研究表明,Ti6Al4V合金表面经激光刻蚀后由亲水变为超亲水状态。经低表面能修饰后,点阵微结构表面符合Wenzel模式的疏水状态,而网格微结构表面符合Wenzel模式的超疏水状态。在点阵和网格微结构上涂覆SiO2形成微纳结构表面均符合Cassie模式的超疏水状态,且网格结构表面的接触角更大,滚动角更小。浅海挂板实验显示,微生物粘膜附着量由多至少的顺序为:超亲水状态的点阵微结构表面亲水的抛光表面超亲水状态的仿生网格微结构表面符合Cassie模式的超疏水表面。

In order to study the impacts of the surface pattern on its wettability and antifouling performance,la-ser etching technique was used to build dot micro-structure and shell surface like grid micro-structure,and the nano-SiO2 powders were coated on the micro-structures to build micro-nano structures.It was shown that after laser etching,Ti6Al4V alloy surface change from hydrophilic state to super hydrophilic one.Trough low sur-face energy modification,the dot micro structure surface was in hydrophobic state that was in accordance with Wenzel model,while the grid micro structure surface was in super hydrophobic state that was in accordance with Wenzel model.The surfaces with the micro-nano structure formed both by coating the nano-SiO2 on the dot or grid micro-structures were both in super hydrophobic state that were in accordance with Cassie model. The grid structure surfaces have greater contact angles and smaller roll angles.Sea-side exposure test showed that the order of the surfaces

利用疏水/超疏水表面获得滴状冷凝进而提高冷凝器传热系数是目前冷凝器强化传热的重要方法。然而，由于冷凝形成的液滴呈黏性极强的Wenzel状态，在重力作用下很难脱落，使得冷凝传热性能尤其在低冷凝负荷时并不能得到显著提高。研究表明：对粗糙表面施加垂直振动，可观察到其表面上液滴浸润状态的转变。今利用聚二甲基硅氧烷(PDMS)为基底采用光刻技术制备了方柱状和方孔状粗糙表面，对振动作用下 Wenzel 状态液滴的浸润状态转变特性进行了对比研究。结果表明，在一定的频率和振幅下，微方柱状表面的 Wenzel 状态液滴可以发生向 Cassie 状态转变，而方孔状表面的液滴则依然保持Wenzel状态。分析认为，在振动作用下粗糙表面Wenzel液滴能否向Cassie状态转变和其表面微观几何结构密切相关，气液固界面三相接触线的连续性是影响液滴浸润状态转变的重要指标，结合表面物理化学和液滴动力学，建立了物理模型对该现象进行了分析。

Using hydrophobic or superhydrophobic surfaces for forming droplet condensation is an important approach to enhance heat transfer in condensers. However, the condensed droplets appearing on the rough surfaces are in Wenzel state. They can hardly be removed from the surfaces, which is detrimental to heat transfer, especially when the loading of a condenser is low. The transition between the Wenzel and Cassie wetting regimes has been previously observed for droplets on a superhydrophobic surface when the surface is vibrating vertically. In this work, the surfaces with square-post and square-pore were prepared respectively on the polydimethyl-siloxane (PDMS) substrate by using photolithography techniques. The wetting transition of the vibrated droplets on the surfaces was analyzed. The experimental results show that the Wenzel state droplets on the surface with square-post can change into Cassie state during vibration at certain frequencies. However, the Wenzel state droplets on

航天器与等离子体环境中的电子、离子相互作用,表面将出现充放电效应,对航天器产生负面影响.表面充电电位对充放电影响至关重要.综合考虑等离子体中粒子质量、温度及密度,二次电子效应及非偏置固体的运动速度等因素,基于气体动理论,利用粒子的麦克斯韦速度分布函数理论推导得出等离子体环境中非偏置固体表面充电电位一般表达式.分析了等离子体以及非偏置固体特殊状态下的表达式及一般状态下的表达式,总结出不同等离子环境、不同运动状态下的表面充电规律.

Within the plasma environment of spacecraft, the interaction between electrons and ions may cause surface charging and discharg-ing and may degrade the performance of spacecraft. The charging potential is a key factor for discharging process. By considering the comprehensive effects of particle mass, temperature, density of plasma, secondary electrons and the velocity of unbiased solid, a general equation of surface charging potential of unbiased solid has been derived using Maxwell velocity distribution function. The expressions under some special and general conditions have been also analyzed. The surface charging and discharging properties are summarized under different plasma environment and motion states of unbiased solid.

利用聚二甲基硅氧烷(PDMS)为基底采用光刻技术制备了微方柱状超疏水表面,分析了冷凝条件下超疏水表面液滴的冷凝生长特征,发现液滴的生长过程可分为微液滴成核冷凝独立生长、冷凝微液滴合并生长以及大液滴生长3个阶段。超疏水表面初始合并的液滴呈Wenzel-Cassie状态和Wenzel状态,随着冷凝液滴的成长,液滴的液-固接触面积与粗糙结构表面的表观面积之比f随着冷凝液滴尺寸的增大而增大,Wenzel-Cassie状态向完全Wenzel状态转变。最后分析了超疏水性破坏的原因。

The square-shaped pillars superhydrophobic surfaces were prepared with the polydimethyl -siloxane ( PDMS) sub-strate using photolithography techniques .The growth dynamics of water droplets condensed on a superhydrophobic geometrically patterned surface were studied .Experimental results show that there are three steps during the growing of the water droplets on the superhydrophbic patterned surface at low temperature .The first step is that the small droplets grow lonely .The second step is that the small droplets coalesce and the last step is that the big droplets grow .Furthermore, the droplets on the surface are Wen-zel-Cassie or Wenzel state at first .With increasing of the size of the droplets , the fraction of the solid-liquid contact area and the solid apparent area increases .The Wenzel-Cassie state of the droplets on the superhydrophobic surfaces transform into the Wenzel state when the size of the droplets increase .

为了更加精确地测量附面层流动状态,并验证表面热膜测试技术的可靠性,利用表面热膜测量了低雷诺数定常来流条件下高负荷涡轮叶栅通道内叶片吸力面附面层的流动状态,并与表面静压实验测得结果进行对比。结果表明,利用表面热膜测得的准壁面剪切力以及相关的统计参数能够准确捕捉到附面层分离泡和转捩的位置,对于高负荷低压涡轮叶型附面层流动测量是可靠有效的。

In order to research boundary layer separation behaviors more accuratly and to prove that the sur-face hot-film testing technique is reliable,a hot-film experimental investigation on steady low Reynolds number boundary layer separation behaviors of the suction surface of a high-loaded low-pressure turbine blade was de-scribed,which was compared with the static pressure experimentation. The experimental results indicate that the quasi-shear stress and the statistical value of the surface hot-film can capture the position of separation bubble and transition accurately. The surface hot-film technique is effective and reliable for measurement on the high-load low-pressure turbine blade.