空化区多相混合流体介质特性实验研究进展

Experimental research on the mixture properties inside cloud cavitation region

  • 摘要: 空化流动是水动力学领域一种特有的流动现象,空化区内部水汽掺混情况复杂,需要借助特殊实验测量手段来获取其中混合介质特性。本文回顾了用于空化区多相混合介质测量的非接触式和接触式实验方法,包括电离辐射、内窥技术、电阻探针和光纤探针等。相比于对实验条件要求较高的非接触式测量技术,接触式探针测量技术更加简便和稳定,可以得到单个测点位置的含汽率、汽泡速度和汽泡尺度等信息。此外,本文还介绍了近年来多相流探针技术在空化流测量中的应用。研究者们分别采用电阻探针和光纤探针,研究了空泡水筒中楔形平板空化和水翼空化内部的介质特性,得到的结果主要包括平均含汽率和汽泡尺度统计分布两方面,发现了云空化区内含汽率高低与空化数密切相关,且楔形平板空化流动和水翼空化流动中存在非常相似的汽泡尺度分布特征。

     

    Abstract: Cavitating flows are unique phenomena in the research field of hydrodynamics. Within the cavitation region, vapor and water are mixed in a complex state. Special experimental techniques are required to obtain the mixture properties. Both non-intrusive and intrusive techniques for cavitating mixture measurement are reviewed, including ionizing radiation, endoscopy, electrical impedance probes and optical fiber probes. In comparison with the experimentally demanding non-intrusive methods, intrusive probe techniques provide simple and stable single-point measurements for the void fraction, bubble velocity and bubble size. Recent applications of phase-resolved probe techniques are then introduced. The electrical impedance probe and optical fiber probe were used in the mixture property measurements in wedge-plate and hydrofoil cavitation, respectively. The time-averaged void fraction and statistical distribution of the bubble size were obtained. The results indicate that the void fraction within cloud cavitation is closely related to the cavitation number, and the characteristics of the bubble size distribution are quite similar between the two kinds of cloud-cavitating flows (wedge-plate and hydrofoil cavitation).

     

/

返回文章
返回