聚乙烯(PE)管道具有优异的化学稳定性,无毒,室温下耐盐酸、氟酸、磷酸、甲酸、胺类、氢氧化钾、氢氧化钠等各种化学物质。聚乙烯管道柔而韧且轻便,并且耐磨损性强,被广泛应用于生活中的各个领域如石油、化工、供水、排水、天然气等领域。一、热老化用途热老化试验主要用于评估 PE 塑料管道在高温环境下的性能变化,包括材料的热稳定性、老化速率、机械性能等方面。通过对样品进行长时间的高温暴露,可以模拟实际使用环境中的热应力对管道材料的影响。
The performance of a vertical axis wind turbine with and without a diffuser was studiedusing direct force measurement technique applied to a scaled model of the rotor in awater tunnel. The experiment was conducted at different tip-speed ratios. The maximumpower coefficient for the turbine was found to be equal to 0.35 for the rotor with diffuserand to 0.26 for the rotor without diffuser. Therefore, the maximum power coefficient wasincreased by 35% when the diffuser was used in the configuration.In the second part of this work, the flow patterns downstream of the turbine werestudied by the particle image velocimetry (PIV) technique. Six different tip-speed ratioswere considered for each configuration (with and without a diffuser). The vorticity andthe streamline plots provide insight into the flow physics in each configuration. Inaddition, the swept area of a full-scale rotor was calculated for both a diffuser-augmentedand a bare turbine for a range of power outputs.