Oil-jet lubrication and cooling of high-speed gears is frequently employed in aeronautical systems, such as novel high-bypass civil aero engines based on the geared turbofan technology. Using such oil-jet system, practitioners aim to achieve high cooling rates on the flanks of the highly thermally loaded gears with minimum oil usage. Thus, for an optimal design, detailed knowledge about the flow processes is desired. These involve the oil exiting the nozzle, the oil impacting on the gear teeth, the oil spreading on the flanks, the subsequent oil fling-off, as well as the effect of the design parameters on the oil flow. Better understanding of these processes will improve the nozzle design phase, e.g. regarding the nozzle positioning and orientation, as well as the nozzle sizing and operation.Most related studies focus on the impingement depth to characterize the two-phase flow. However, the level of information of this scalar value is rather low for a complete description of the highly dynamic three-dimensional flow. Motivated by the advancements in numerical methods and the computational resources available nowadays, the investigation of the oil-jet gear interaction by means of computational fluid dynamics (CFD) has come into focus lately.In this work, a numerical setup based on the volume-of-fluid method is presented and employed to investigate the two-phase flow phenomena occurring in the vicinity of the gear teeth. The setup consists of a single oil-jet impinging on a single rotating spur gear. By introducing new metrics for characterizing the flow phenomena, extensive use of the possibilities of modern CFD is made, allowing a detailed transient and spatially resolved flow analysis. Thus, not only the impingement depth, but also the temporal and spatial evolution of wetted areas on the gear flanks, as well as the evolution of the oil volume in contact with the gear flanks are extracted from the simulation data and compared in a CFD study.The study consists of 21 different simulation cases, whereby the effect of varying the jet velocity, the jet inclination angle, the jet diameter, and the gear speed are examined. Consistent results compared to a simplified analytical approach for the impinging depth are obtained and the results for the newly introduced metrics are presented.

中文翻译：

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正齿轮中喷油齿轮相互作用流动现象的 CFD 研究

高速齿轮的喷油润滑和冷却经常用于航空系统，例如基于齿轮传动涡扇技术的新型高涵道比民用航空发动机。使用这种喷油系统，从业者旨在以最少的油用量在高热负荷齿轮的侧面实现高冷却速率。因此，对于优化设计，需要有关流动过程的详细知识。这些包括从喷嘴流出的油、冲击齿轮齿的油、在侧面扩散的油、随后的油甩出以及设计参数对油流的影响。更好地理解这些过程将改进喷嘴设计阶段，例如关于喷嘴定位和方向，以及喷嘴尺寸和操作。大多数相关研究都集中在冲击深度来表征两相流。然而，这个标量值的信息水平对于一个高度动态的三维流动的完整描述来说是相当低的。在数值方法的进步和当今可用的计算资源的推动下，通过计算流体动力学（CFD）研究喷油齿轮相互作用最近成为焦点。在这项工作中，基于体积的数值设置 -提出并采用流体法来研究发生在轮齿附近的两相流动现象。该装置包括一个单一的喷油器撞击一个旋转的正齿轮。通过引入用于表征流动现象的新指标，广泛使用现代 CFD 的可能性，允许进行详细的瞬态和空间分辨流动分析。因此，从模拟数据中不仅提取了冲击深度，还提取了齿轮侧面润湿区域的时间和空间演变，以及与齿轮侧面接触的油量的演变，并在 CFD 研究中进行了比较. 该研究由 21 个不同的模拟案例组成，研究了改变射流速度、射流倾角、射流直径和齿轮速度的影响。与撞击深度的简化分析方法相比，获得了一致的结果，并给出了新引入的指标的结果。以及与齿轮齿面接触的油量的演变从模拟数据中提取并在 CFD 研究中进行比较。该研究由 21 个不同的模拟案例组成，其中改变射流速度、射流倾角的影响，射流直径和齿轮速度进行了检查。与撞击深度的简化分析方法相比，获得了一致的结果，并给出了新引入的指标的结果。以及与齿轮齿面接触的油量的演变从模拟数据中提取并在 CFD 研究中进行比较。该研究由 21 个不同的模拟案例组成，其中改变射流速度、射流倾角的影响，射流直径和齿轮速度进行了检查。与撞击深度的简化分析方法相比，获得了一致的结果，并给出了新引入的指标的结果。