Heat transfer through impingement cooling of a rotating cylinder

齿轮传动涡扇发动机是目前用于降低民用飞机发动机比油耗和噪声排放的概念。通过使用高性能变速器，可以实现更大的旁路比，从而提高推进效率。为了确保行星减速箱的安全运行，需要精确的热预算知识。用弹性流体力学方法可以很精确地确定啮合过程中齿面滑动引起的润滑膜中的热释放。然而，目前还没有关于齿轮冲击冷却过程中的传热模型。拟议的项目应有助于更好地了解冲击冷却过程，并有助于建立正齿轮冲击冷却过程的模型。冲击冷却换热的实验研究表明，齿轮冷却的高度非稳态换热过程以冲击过程为主。这一子过程应通过旋转圆柱体冲击冷却的实验研究来进行基础研究。实验数据将被用来描述喷流撞击过程中的流动行为。此外，还需要推导出热传递的关联式。在项目的第二部分，旋转圆柱体上的实验结果将与现有的直齿轮冲击冷却实验数据进行比较。应研究是否以及如何将气缸冷却的模型转移到直齿圆柱齿轮的冲击冷却。检测到的差异将被用来定义第二个应用期的实验。

The geared turbofan engine is a current concept for reducing the specific fuel consumption and noise emissions of civil aircraft engines. By using a high-performance transmission, larger bypass ratios can be achieved, resulting in increased propulsion efficiency. In order to ensure safe operation of the planetary reduction gearbox, precise knowledge of the thermal budget is required. The heat release in the lubricating film due to the sliding of the tooth flanks in mesh can be determined sufficiently precisely by the elastohydrodynamics. A model for the heat transfer during impingement cooling of the gears, however, is not yet available. The proposed project should contribute to a better understanding of the impingement cooling process and to the modelling of the impingement cooling process of spur gears. Experimental investigations of the heat transfer in impingement cooling have shown that the highly unsteady heat transfer process in gear cooling is dominated by the impact process. This sub-process shall be investigated fundamentally by experimental investigations through impingement cooling of a rotating cylinder. The experimental data will be used to characterise the flow behaviour during jet impact. Furthermore, a correlation for the heat transfer is to be derived. In a second part of the project, the findings from the experiments on the rotating cylinder will be compared with the existing experimental data on impingement cooling on the spur gear. It shall be investigated whether and how the model for cylinder cooling can be transferred to the impingment cooling of spur gears. The detected differences will be used to define experiments for a second application period.