非牛顿气液两相流广泛存在于工农业生产中,气泡和液相间的接触非常复杂,对相间的传递效率具有重要的影响。为了理解气泡在非牛顿流体中的运动特性,基于连续表面张力模型与Carreau本构模型,本文运用volume of fluid (VOF)法研究了单气泡...非牛顿气液两相流广泛存在于工农业生产中,气泡和液相间的接触非常复杂,对相间的传递效率具有重要的影响。为了理解气泡在非牛顿流体中的运动特性,基于连续表面张力模型与Carreau本构模型,本文运用volume of fluid (VOF)法研究了单气泡在剪切稀化流体内自由上浮的运动特性。研究发现:气泡的动力学特性与液相的特征时间λ密切相关,液相的剪切稀化程度越强(流变指数n越小)或表面张力越小(Eo数越大)时,特征时间λ对气泡变形和尾涡的影响越大。在给定的剪切稀化程度和表面张力下,λ越大,气泡终端速度越大,其尾涡强度和尺度也越大,导致气泡周围液相高剪切速率区和低表观黏度区的范围越宽。此外,当液相的表面张力较小时,在气泡尾部出现了黏度盲区;并且随着λ的增大,黏度盲区逐渐脱离气泡尾部并破碎;黏度盲区的出现减小了气泡周围液相低表观黏度区的面积,增大了气泡上浮过程的摩擦阻力,降低了气泡的终端速度。展开更多
A novel floating foundation to support the NREL offshore 5 MW wind turbine was designed conceptually by combining the characteristics of barge and Spar. The main focus was structural design and hydrodynamic modelling....A novel floating foundation to support the NREL offshore 5 MW wind turbine was designed conceptually by combining the characteristics of barge and Spar. The main focus was structural design and hydrodynamic modelling. Based on this novel floating foundation, the hydrodynamic performance was investigated in the frequency domain and time domain by using the wave analysis software Hydro D and Deep C from Det Norske Veritas. The frequency domain analysis was conducted to investigate the effects of the incident wave angle and water depth. The time-domain analysis was carried out to evaluate the response of the floating foundation under a selected operational condition. The hydrodynamic performances of this floating foundation with respect to time series and response spectra were also investigated in this study.展开更多
文摘非牛顿气液两相流广泛存在于工农业生产中,气泡和液相间的接触非常复杂,对相间的传递效率具有重要的影响。为了理解气泡在非牛顿流体中的运动特性,基于连续表面张力模型与Carreau本构模型,本文运用volume of fluid (VOF)法研究了单气泡在剪切稀化流体内自由上浮的运动特性。研究发现:气泡的动力学特性与液相的特征时间λ密切相关,液相的剪切稀化程度越强(流变指数n越小)或表面张力越小(Eo数越大)时,特征时间λ对气泡变形和尾涡的影响越大。在给定的剪切稀化程度和表面张力下,λ越大,气泡终端速度越大,其尾涡强度和尺度也越大,导致气泡周围液相高剪切速率区和低表观黏度区的范围越宽。此外,当液相的表面张力较小时,在气泡尾部出现了黏度盲区;并且随着λ的增大,黏度盲区逐渐脱离气泡尾部并破碎;黏度盲区的出现减小了气泡周围液相低表观黏度区的面积,增大了气泡上浮过程的摩擦阻力,降低了气泡的终端速度。
基金Supported by the National Natural Science Foundation of China(No.51479134)the Science Fund for Creative Research Groups of the National Natural Science Foundation of China(No.51321065)the State Key Laboratory of Hydraulic Engineering Simulation and Safety
文摘A novel floating foundation to support the NREL offshore 5 MW wind turbine was designed conceptually by combining the characteristics of barge and Spar. The main focus was structural design and hydrodynamic modelling. Based on this novel floating foundation, the hydrodynamic performance was investigated in the frequency domain and time domain by using the wave analysis software Hydro D and Deep C from Det Norske Veritas. The frequency domain analysis was conducted to investigate the effects of the incident wave angle and water depth. The time-domain analysis was carried out to evaluate the response of the floating foundation under a selected operational condition. The hydrodynamic performances of this floating foundation with respect to time series and response spectra were also investigated in this study.
