在实际气层中,束缚水以毛管束缚水和水膜形式存在。根据由Derjaguin-Landau-Verwey-Overbee理论建立的总分离压和水膜厚度的理论计算模型,结合扩展Young-Laplace公式,采用迭代算法,提出了计算储层水膜厚度的图解法。利用实际地层实测温...在实际气层中,束缚水以毛管束缚水和水膜形式存在。根据由Derjaguin-Landau-Verwey-Overbee理论建立的总分离压和水膜厚度的理论计算模型,结合扩展Young-Laplace公式,采用迭代算法,提出了计算储层水膜厚度的图解法。利用实际地层实测温度、压力数据,得到总分离压与水膜厚度曲线,求得在气藏中部孔隙中的水膜厚度远小于含气孔隙半径。在实际气藏的高矿化度水溶液中,静电斥力较小,只有Van der Waals引力是保持水膜稳定的主要作用力,因此气藏孔隙中水膜厚度小。对比临界孔隙半径和水膜厚度的计算值表明,束缚水主要以毛管束缚水的形式存在,水膜厚度远小于含气孔隙的半径,对天然气渗流的影响小。展开更多
Drag reduction features in the transition regime of channel flow with fibre suspension were analyzed in terms of the linear stability theory. The modified stability equation was obtained based on the slender-body theo...Drag reduction features in the transition regime of channel flow with fibre suspension were analyzed in terms of the linear stability theory. The modified stability equation was obtained based on the slender-body theory and natural closure approximation. Results of the stability analysis show attenuating effects of fibre additives to the flow instability. For the cases leading to transition, drag reduction rate increases with the characteristic parameter H of fibres. The mechanism of drag reduction by fibres is revealed through the variation of velocity profile and the decrease of wall shear stress. The theoretical results are qualitatively consistent with some typical experiments.展开更多
Three different kinds of closure model of fiber orientation tensors were applied to simulate numerically the hydrodynamic stability of fiber suspensions in a channel flow. The effects of closure models and three_dimen...Three different kinds of closure model of fiber orientation tensors were applied to simulate numerically the hydrodynamic stability of fiber suspensions in a channel flow. The effects of closure models and three_dimensional (3_D) orientation distribution of fibers on the results of stability analysis were examined. It is found that the relationship of the behavior in hydrodynamic stability and the parameter of the fiber given by all the three models are the same. However, the attenuation of flow instability is most distinct using 3_D hybrid model because the orientation of the fiber departures from the flow direction, and least apparent using its 2_D counterpart for that the fibers show a tendency towards alignment with the flow direction in this case.展开更多
Different from previous temporal evolution assumption, the spatially growing mode was employed to analyze the linear stability for the channel flow of fiber suspensions. The stability equation applicable to fiber susp...Different from previous temporal evolution assumption, the spatially growing mode was employed to analyze the linear stability for the channel flow of fiber suspensions. The stability equation applicable to fiber suspensions was established and solutions for a wide range of Reynolds number and angular frequency were given numerically . The results show that, the flow instability is governed by a parameter H which represents a ratio between the axial stretching resistance of fiber and the inertial force of the fluid. An increase of H leads to a raise of the critical Reynolds number, a decrease of corresponding wave number, a slowdown of the decreasing of phase velocity , a growth of the spatial attenuation rate and a diminishment of the peak value of disturbance velocity. Although the unstable region is reduced on the whole, long wave disturbances are susceptible to fibers.展开更多
文摘在实际气层中,束缚水以毛管束缚水和水膜形式存在。根据由Derjaguin-Landau-Verwey-Overbee理论建立的总分离压和水膜厚度的理论计算模型,结合扩展Young-Laplace公式,采用迭代算法,提出了计算储层水膜厚度的图解法。利用实际地层实测温度、压力数据,得到总分离压与水膜厚度曲线,求得在气藏中部孔隙中的水膜厚度远小于含气孔隙半径。在实际气藏的高矿化度水溶液中,静电斥力较小,只有Van der Waals引力是保持水膜稳定的主要作用力,因此气藏孔隙中水膜厚度小。对比临界孔隙半径和水膜厚度的计算值表明,束缚水主要以毛管束缚水的形式存在,水膜厚度远小于含气孔隙的半径,对天然气渗流的影响小。
基金the National Natural Science Foundation of China (No. 10372090 and No. 10102017).
文摘Drag reduction features in the transition regime of channel flow with fibre suspension were analyzed in terms of the linear stability theory. The modified stability equation was obtained based on the slender-body theory and natural closure approximation. Results of the stability analysis show attenuating effects of fibre additives to the flow instability. For the cases leading to transition, drag reduction rate increases with the characteristic parameter H of fibres. The mechanism of drag reduction by fibres is revealed through the variation of velocity profile and the decrease of wall shear stress. The theoretical results are qualitatively consistent with some typical experiments.
基金ProjectsupportedbytheNationalNaturalScienceFoundationofChina (No .1 0 3 72 0 90 )
文摘Three different kinds of closure model of fiber orientation tensors were applied to simulate numerically the hydrodynamic stability of fiber suspensions in a channel flow. The effects of closure models and three_dimensional (3_D) orientation distribution of fibers on the results of stability analysis were examined. It is found that the relationship of the behavior in hydrodynamic stability and the parameter of the fiber given by all the three models are the same. However, the attenuation of flow instability is most distinct using 3_D hybrid model because the orientation of the fiber departures from the flow direction, and least apparent using its 2_D counterpart for that the fibers show a tendency towards alignment with the flow direction in this case.
基金Foundation item: the National Natural Science Foundation of China for Outstanding Young Sci-entists (19925210)
文摘Different from previous temporal evolution assumption, the spatially growing mode was employed to analyze the linear stability for the channel flow of fiber suspensions. The stability equation applicable to fiber suspensions was established and solutions for a wide range of Reynolds number and angular frequency were given numerically . The results show that, the flow instability is governed by a parameter H which represents a ratio between the axial stretching resistance of fiber and the inertial force of the fluid. An increase of H leads to a raise of the critical Reynolds number, a decrease of corresponding wave number, a slowdown of the decreasing of phase velocity , a growth of the spatial attenuation rate and a diminishment of the peak value of disturbance velocity. Although the unstable region is reduced on the whole, long wave disturbances are susceptible to fibers.
