叶片表面超亲水和超疏水特性对二次水滴形成影响的研究

Influence of Blade Surface Super-hydrophilic and Super-hydrophobic Property on Formation of Secondary Droplets

为了探索减轻汽轮机低压叶片水蚀破坏的新措施,从二次水滴的形成机理出发,提出叶片表面进行超亲水和超疏水处理,搭建了水滴形成试验台,模拟汽轮机内叶片表面水膜在超亲水和超疏水表面破碎形成水滴的过程,采用单帧单曝光图像法测量了水滴粒径和速度,得到了试样模拟叶片表面亲疏水性能对二次水滴粒径和速度的影响规律.结果表明:与普通试样模拟叶片和超疏水处理的试样模拟叶片相比,超亲水处理试样模拟叶片所形成水滴的尺寸较小,较小水滴易被主汽流携带加速,可以减轻水蚀破坏;通过对静叶片表面进行超亲水处理有可能减轻叶片水蚀.

To reduce the erosion damage of low-pressure turbine blades by water impact,considering the formation mechanism of secondary water droplets,a suggestion was proposed to take super-hydrophilic and super-hydrophobic treatment to relevant blade surfaces,based on which a test platform was set up to simulate the process of water film fragmentation on the super-hydrophilic and super-hydrophobic surfaces, and the process of formation of secondary droplets in the steam turbine.The particle size and velocity of water droplets were measured using single frame single exposure imaging method,and subsequently the influence of surface hydrophilicity and hydrophobicity of simulation blades on formation of droplets was analyzed.Results show that,compared with ordinary and super-hydrophobic surface,small-sized droplets are easy to generate on the super-hydrophilic blade surface,which will be carried over by main steam flow, and therefore producing slight water droplet impact damage;super-hydrophilic treatment to stationary blade may help to reduce the water droplet impact damage.