Purpose

The presence of air in the water flow over the hydrofoil is investigated. The examined hydrofoil is ClarkY 11.7% with an angle of attack of 8 deg. The flow simulations are performed with the assumption of different models. The Singhal cavitation model and the models which resolve the non-condensable gas including 2phases and 3phases are implemented in the numerical model. The calculations are performed with the uRANS model with assumption of the constant temperature of the mixture. The two-phase flow is simulated with a mixture model. The dynamics and structures of cavities are compared with literature data and experimental results.

Design/methodology/approach

The cavitation regime can be observed in some working conditions of turbomachines. The phase transition, which appears on the blades, is the source of high dynamic forces, noise and also can lead to the intensive erosion of the blade surfaces. The need to control this process and to prevent or reduce the undesirable effects can be fulfilled by the application of non-condensable gases to the liquid.

Findings

The results show that the Singhal cavitation model predicts the cavity structure and related characteristics differently with 2phases and 3phases models at low cavitation number where the cavitating flow is highly dynamic. On the other hand, the impact of dissolved air on the cloud structure and dynamic characteristic of cavitating flow is gently observable.

Originality/value

The originality of this paper is the evaluation of different numerical cavitation models for the prediction of dynamic characteristics of cavitating flow in the presence of air.

中文翻译：

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空气存在下水翼上空化流动的数值研究

目的

研究了水翼上的水流中空气的存在。被检查的水翼为 ClarkY 11.7%，攻角为 8 度。流动模拟是在不同模型的假设下进行的。在数值模型中实现了Singhal空化模型和求解不凝性气体的两相和三相模型。使用 uRANS 模型进行计算，并假设混合物的温度恒定。用混合模型模拟两相流。将空腔的动力学和结构与文献数据和实验结果进行了比较。

设计/方法/方法

在涡轮机的某些工作条件下可以观察到空化状态。出现在叶片上的相变是高动态力、噪音的来源，也可能导致叶片表面的强烈腐蚀。控制该过程并防止或减少不良影响的需要可以通过将不凝性气体应用于液体来实现。

发现

结果表明，Singhal 空化模型在空化流动高度动态的低空化数下与 2 相和 3 相模型对空腔结构和相关特性的预测不同。另一方面，溶解空气对云结构和空化流动态特性的影响是可以观察到的。

原创性/价值

本文的独创性在于评估不同的数值空化模型，以预测空气中空化流的动态特性。