含盐海水飞沫的结冰风洞试验相似准则

Scaling law for salty sea spray icing wind tunnel test

舰船在极地低温海域航行时,空气中存在大量低温含盐海水飞沫。长时间暴露在飞沫中会导致舰船结构结冰,影响正常航行。结冰风洞试验是研究飞沫结冰问题的重要手段,但使用含盐水会腐蚀设备,目前无法在大型结冰风洞中进行飞沫结冰试验。开展含盐海水飞沫结冰的相似准则研究,可以实现使用纯水模拟含盐飞沫结冰。通过测试和分析多种组分的海水样本物性参数,在经典相似理论的基础上,补充水膜厚度的韦伯数调和含盐水与纯水的表面张力差异,重新构造含盐水的冻结系数确保相变过程能量守恒。最终建立含盐飞沫结冰的参数方程,形成对应的相似转换方法流程。对NACA0012模型在飞沫结冰条件下的试验工况进行转换,使用NNW-ICE软件验证相似准则。结果表明,通过建立的相似准则,使用纯水可以模拟含盐飞沫结冰冰形,为大型结冰风洞开展含盐飞沫结冰研究提供了有力理论支撑。

When ships navigate in polar regions,a large amount of low-temperature salt-containing spray exists in the air.Long-term exposure to the spray can cause the upper structure of the vessel and the internal intake of gas turbines to freeze,affecting the normal navigation of the ship.Large-scale icing wind tunnels can simulate the ice accretion of sea spray on ship components or scaled models,but the corrosive effect of seawater spray can endanger equipment’s safety.Therefore,sea spray icing experiments were conducted on small-scale equipment.The study of scaling law was conducted in a wind tunnel to simulate the icing of salinity sea spray.Physical properties were tested on various components of seawater samples,obtaining the surface tension,thermal conductivity,specific heat capacity,phase transition temperature,and latent heat.On the basis of classical similarity theory,the main differences between the icing of sea spray and pure water were analyzed.The classical icing wind tunnel scaling law was adopted and modified with the extension of the water film similarity and sea spray freezing coefficient.Ultimately,a scaling parameter equation for salinity sea spray icing was established,along with a corresponding process for scaling transformation.The icing condition of the NACA0012 model under sea spray conditions was scaled with the established scaling law,and the NNW-ICE software is used to validate the scaling law.The results indicate that via establishing the scaling law,it is possible to simulate the ice shape of salinity sea spray using pure water in icing wind tunnel tests.This study provides significant theoretical support for large-scale icing wind tunnels to conduct sea spray icing tests.