电场中的气泡对于强化传热有显著的作用,对于电场中气泡动力学特性的研究对增强换热器效率,提高能源利用率有重要意义.为了获得外加电场作用下气泡的动力学特性,设计与搭建了可视化实验平台.采用50 k V高压直流电源构建均匀电场,高清摄...电场中的气泡对于强化传热有显著的作用,对于电场中气泡动力学特性的研究对增强换热器效率,提高能源利用率有重要意义.为了获得外加电场作用下气泡的动力学特性,设计与搭建了可视化实验平台.采用50 k V高压直流电源构建均匀电场,高清摄像机拍摄实验图像.引入电场强度、气泡体积与溶液介电常数作为变量,探究其对于气泡动力学特性的影响.观测了竖直与水平均匀电场中气泡的上升过程,分析了不同变量下气泡变形状况与上升速度的变化.引入气泡长宽比L/D用于表示气泡拉伸变形程度,截取单个气泡上升过程分时段图像展示形态变化过程.研究结果表明,气泡沿电场方向伸长,且电场强度越大,变形越明显;竖直电场中气泡伸长导致上升速度增大,而水平电场中气泡上升速度减小.气泡尺寸增大,浮升力作用增强,气泡上升速度增大.溶液介电常数增加,电场力作用明显增加,气泡变形更加明显.展开更多
In order to solve the hardening problem of complex calcium lubricating grease, the water absorption test of several calcium salts was carried out, and it was found that calcium 12-hydroxystearate did not absorb water,...In order to solve the hardening problem of complex calcium lubricating grease, the water absorption test of several calcium salts was carried out, and it was found that calcium 12-hydroxystearate did not absorb water, and calcium acetate, calcium phosphate and calcium borate had different degrees of water absorption. Calcium acetate has the highest water absorption rate, while calcium phosphate and calcium borate show comparable water absorption rates. Upon using the molecular simulation technology, it is found that in the complex calcium grease system, calcium phosphate and calcium borate tend to combine with water, which inhibits the water absorption of calcium acetate and alleviate the hardening problem.展开更多
文摘电场中的气泡对于强化传热有显著的作用,对于电场中气泡动力学特性的研究对增强换热器效率,提高能源利用率有重要意义.为了获得外加电场作用下气泡的动力学特性,设计与搭建了可视化实验平台.采用50 k V高压直流电源构建均匀电场,高清摄像机拍摄实验图像.引入电场强度、气泡体积与溶液介电常数作为变量,探究其对于气泡动力学特性的影响.观测了竖直与水平均匀电场中气泡的上升过程,分析了不同变量下气泡变形状况与上升速度的变化.引入气泡长宽比L/D用于表示气泡拉伸变形程度,截取单个气泡上升过程分时段图像展示形态变化过程.研究结果表明,气泡沿电场方向伸长,且电场强度越大,变形越明显;竖直电场中气泡伸长导致上升速度增大,而水平电场中气泡上升速度减小.气泡尺寸增大,浮升力作用增强,气泡上升速度增大.溶液介电常数增加,电场力作用明显增加,气泡变形更加明显.
文摘In order to solve the hardening problem of complex calcium lubricating grease, the water absorption test of several calcium salts was carried out, and it was found that calcium 12-hydroxystearate did not absorb water, and calcium acetate, calcium phosphate and calcium borate had different degrees of water absorption. Calcium acetate has the highest water absorption rate, while calcium phosphate and calcium borate show comparable water absorption rates. Upon using the molecular simulation technology, it is found that in the complex calcium grease system, calcium phosphate and calcium borate tend to combine with water, which inhibits the water absorption of calcium acetate and alleviate the hardening problem.
