活塞冷却系统是影响发动机热管理的关键因素之一。当前，在活塞头内部使用冷却通道使得可以优化热量提取并有效地控制活塞温度。然而，由于活塞通道中的空间小且结构复杂，因此在实验上很难对内部冷却油进行精确的目视观察并研究传热特性。在当前的工作中，使用了一个高速摄像机来捕获简化曲柄通道内各种曲柄角下水和空气的流动模式。探讨了气液两相流在往复运动过程中的传热机理。讨论了振荡频率和注水率的影响。已开发出一种有效的方法来全面了解活塞冷却通道内冷却介质的流动和传热特性。这可以为将来优化发动机的热管理提供一种有效的方法。
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Experimental visualization of gas–liquid two-phase flow during reciprocating motion
The piston-cooling system is one of the critical elements that impact on the thermal management of engines. At present, the use of a cooling gallery inside the piston head makes it possible to optimize the heat extraction and control the piston temperature effectively. However, owing to the small space in piston galleries and their complicated structure, it is rather difficult experimentally to perform accurate visual observations of the internal cooling oil and study the heat transfer characteristics. In the current work, a high-speed camera was employed to capture the flow patterns of water and air inside a simplified piston gallery at various crank angles. The heat transfer mechanisms in gas–liquid two-phase flow during reciprocating motion were explored. The effects of oscillation frequency and water filling ratio were discussed. An effective method was developed to achieve a full understanding of the flow and heat transfer characteristics of cooling medium inside a piston cooling gallery. This could provide an effective method to optimize the thermal management of engines in future.