In the present research, a bubble dynamics based model for cavitating flow simulations is extended to higher void fraction region for wider range of applications. The present bubble model is based on the so-called Ray...In the present research, a bubble dynamics based model for cavitating flow simulations is extended to higher void fraction region for wider range of applications. The present bubble model is based on the so-called Rayleigh-Plesset equation that calculates a temporal bubble radius with the surrounding liquid pressure and is considered to be valid in an area below a certain void fraction. The solution algorithm is modified so that the Rayleigh-Plesset equation is no more solved once the bubble radius （or void fraction） reaches at a certain value till the liquid pressure recovers above the vapor pressure in order to overcome this problem. This procedure is expected to stabilize the numerical calculation. The results of simple two-dimensional flow field are presented compared with the existing bubble model.展开更多
基于商用CFD软件Fluent 160,采用Mixture多相流模型、Schnerr and Sauer空化模型和Re-alizablek-e湍流模型,建立了圆盘空化器超空化流动的三维计算模型,开展了模型验证工作,研究了流域径向尺度对自然超空泡形态的影响。结果表明流域径...基于商用CFD软件Fluent 160,采用Mixture多相流模型、Schnerr and Sauer空化模型和Re-alizablek-e湍流模型,建立了圆盘空化器超空化流动的三维计算模型,开展了模型验证工作,研究了流域径向尺度对自然超空泡形态的影响。结果表明流域径向尺度对超空泡形态有显著影响。流域径向尺度不足时空泡明显偏大;随流域径向尺度的增加超空泡的尺寸逐渐减小并收敛;当流域具有36倍以上的径向比尺度时,超空泡外形收敛并且与经验公式的计算结果吻合,可用于指导工程实践。展开更多
In this paper, recent measurements of tip vortex flow with and without cavitation carried out in Cavitation Mechanism Tunnel of China Ship Scientific Research Center（CSSRC） are presented. The elliptic hydrofoil with...In this paper, recent measurements of tip vortex flow with and without cavitation carried out in Cavitation Mechanism Tunnel of China Ship Scientific Research Center（CSSRC） are presented. The elliptic hydrofoil with section NACA 662-415 was adopted as test model. High-speed video（HSV） camera was used to visualize the trajectory of tip vortex core and the form of tip vortex cavitation（TVC） in different cavitation situations. Laser Doppler velocimetry（LDV） was employed to measure the tip vortex flow field in some typical sections along the vortex trajectory with the case of cavitation free. Stereo particle image velocimetry（SPIV） system was used to measure the velocity and vorticity distributions with and without cavitation. Series measurement results such as velocity and vorticity distributions, the trajectory of tip vortex core, the vortex core radius, cavity size and cavitation inception number were obtained. The results demonstrated that the minimum pressure coefficient in the vortex core obtained by flow field measurement was quite coincident with the tip vortex cavitation inception number obtained under the condition of high incoming velocity and low air content. And TVC would decrease the vortex strength comparing with the case without cavitation.展开更多
文摘In the present research, a bubble dynamics based model for cavitating flow simulations is extended to higher void fraction region for wider range of applications. The present bubble model is based on the so-called Rayleigh-Plesset equation that calculates a temporal bubble radius with the surrounding liquid pressure and is considered to be valid in an area below a certain void fraction. The solution algorithm is modified so that the Rayleigh-Plesset equation is no more solved once the bubble radius （or void fraction） reaches at a certain value till the liquid pressure recovers above the vapor pressure in order to overcome this problem. This procedure is expected to stabilize the numerical calculation. The results of simple two-dimensional flow field are presented compared with the existing bubble model.
文摘基于商用CFD软件Fluent 160,采用Mixture多相流模型、Schnerr and Sauer空化模型和Re-alizablek-e湍流模型,建立了圆盘空化器超空化流动的三维计算模型,开展了模型验证工作,研究了流域径向尺度对自然超空泡形态的影响。结果表明流域径向尺度对超空泡形态有显著影响。流域径向尺度不足时空泡明显偏大;随流域径向尺度的增加超空泡的尺寸逐渐减小并收敛;当流域具有36倍以上的径向比尺度时,超空泡外形收敛并且与经验公式的计算结果吻合,可用于指导工程实践。
基金Project supported by the Key Project of National Natural Science Foundation of China(Grant No.11332009)
文摘In this paper, recent measurements of tip vortex flow with and without cavitation carried out in Cavitation Mechanism Tunnel of China Ship Scientific Research Center（CSSRC） are presented. The elliptic hydrofoil with section NACA 662-415 was adopted as test model. High-speed video（HSV） camera was used to visualize the trajectory of tip vortex core and the form of tip vortex cavitation（TVC） in different cavitation situations. Laser Doppler velocimetry（LDV） was employed to measure the tip vortex flow field in some typical sections along the vortex trajectory with the case of cavitation free. Stereo particle image velocimetry（SPIV） system was used to measure the velocity and vorticity distributions with and without cavitation. Series measurement results such as velocity and vorticity distributions, the trajectory of tip vortex core, the vortex core radius, cavity size and cavitation inception number were obtained. The results demonstrated that the minimum pressure coefficient in the vortex core obtained by flow field measurement was quite coincident with the tip vortex cavitation inception number obtained under the condition of high incoming velocity and low air content. And TVC would decrease the vortex strength comparing with the case without cavitation.
