Thermodynamic Effect on Rotating Cavitation in an Inducer-猫眼课题宝

DOI：

10.1115/fedsm2007-37468

发表时间：

2009-09

期刊：

影响因子：

通讯作者：

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其他

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作者：

Y. Yoshida;Yoshifumi Sasao;Mitsuo Watanabe;Tomoyuki Hashimoto;Y. Iga;T. Ikohagi

诱导轮中的旋转空化被称为一种空化不稳定性，其中不均匀的空腔模式以与转子相同的方向传播，传播速度比为 1.0-1.2。由于诱导轮上的不稳定横向载荷的增加，这种旋转空化导致轴振动。另一方面，由于空腔周围的热不平衡，低温流体中的空化具有热力学效应。由于延迟空腔生长，它提高了空化性能。然而，热力学效应与空化不稳定性之间的关系仍然未知。为了研究热力学效应对旋转空化的影响，我们进行了将液氮设置在不同温度（74 K、78 K 和 83 K）的实验，重点关注空化腔长度。在较高的空化数下，超同步旋转空化（Super-SRC）发生在Lc/h≅0.5的临界腔长处，并且在腔长波动方面热力学效应较弱。相比之下，在较低的空化数下，同步旋转空化（SRC）发生在临界空化长度 Lc/h ≅ 0.9–1.0 处。由于热力学效应抑制了空穴的生长，临界空化数移至较低水平，随着液体温度的升高，这种现象显着出现。热力学效应减小了同步旋转空化下空腔长度的不均匀性。此外，我们还证实，在旋转空化条件下，作用在诱导轮上的流体力显着增加，但轴振动的幅度通过热力学效应取决于空腔长度的不均匀程度。Copyright © 2007 by ASME

Rotating cavitation in inducers is known as one type of cavitation instability, in which an uneven cavity pattern propagates in the same direction as the rotor with a propagating speed ratio of 1.0–1.2. This rotating cavitation causes shaft vibration due to the increase of the unsteady lateral load on the inducer. On the other hand, cavitation in cryogenic fluids has a thermodynamic effect because of the thermal imbalance around the cavity. It improves cavitation performances due to the delay of cavity growth. However, the relationship between the thermodynamic effect and cavitation instabilities is still unknown. To investigate the influence of the thermodynamic effect on rotating cavitation, we conducted experiments in which liquid nitrogen was set at different temperatures (74 K, 78 K and 83 K) with a focus on the cavity length. At higher cavitation numbers, super-synchronous rotating cavitation (Super-SRC) occurred at the critical cavity length of Lc/h ≅ 0.5 with a weak thermodynamic effect in terms of the fluctuation of cavity length. In contrast, synchronous rotating cavitation (SRC) occurred at the critical cavity length of Lc/h ≅ 0.9–1.0 at lower cavitation numbers. The critical cavitation number shifted to a lower level due to the suppression of cavity growth by the thermodynamic effect, which appeared significantly with rising liquid temperature. The unevenness of cavity length under synchronous rotating cavitation was decreased by the thermodynamic effect. Furthermore, we confirmed that the fluid force acting on the inducer notably increased under conditions of rotating cavitation, but that the amplitude of the shaft vibration depended on the degree of the unevenness of the cavity length through the thermodynamic effect.Copyright © 2007 by ASME

Thermodynamic Effect on Rotating Cavitation in an Inducer

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