Heat transfer through impingement cooling of a rotating cylinder

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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.