The labyrinth seal in turbomachinery is a key element that restricts leakage flow among rotor-stator clearances from high-pressure regions to low-pressure regions. The fluid-induced forces on the rotor from seals duri...The labyrinth seal in turbomachinery is a key element that restricts leakage flow among rotor-stator clearances from high-pressure regions to low-pressure regions. The fluid-induced forces on the rotor from seals during machine operation must be accurately quantified to predict their dynamic behavior effectively. To understand the fluid-induced force characteristics of the labyrinth seal more fully, the effects of four types of pre-swirls on the leakage, flow field, and fluid-induced force of a rotary straight-through labyrinth gas seal (RSTLGS) were numerically investigated using the proposed steady computational fluid dynamics (CFD) method based on the three-dimensional models of the RSTLGS. The leakage, flow field, and fluid-induced force of the RSTLGS for six axial pre-swirl velocities, four radial preswirl angles, four circumferential positive pre-swirl angles, and four circumferential negative pre-swirl angles were computed under the same geometrical parameters and operational conditions. Mesh analysis ensures the accuracy of the present steady CFD method. The numerical results show that the four types of pre-swirls influence the leakage, flow field, and fluid-induced force of the RSTLGS. The axial pre-swirl velocity remarkably inhibits the fluid-induced force, and the circumferential positive pre-swirl angle and circumferential negative pre-swirl angle remarkably promote the fluid-induced force. The effects of the radial pre-swirl angle on the fluid-induced force are complicated, and the pressure forces and viscous forces show the maximum or minimum values at a specific radial pre-swirl angle. The pre-swirl has a negligible impact on the leakage. The four types of pre-swirls affect the leakage, flow field, and fluidinduced force of the RSTLGS to varying degrees. The pre-swirl is the influence factor affecting the leakage, flow field, and fluid-induced force of the RSTLGS. The conclusions will help to understand the fluid-induced force of labyrinth seals more fully, by providing helpful suggestions for engineering practices and a theoretical basis to analyze the fluid–structure interaction of the seal-rotor system in future research.展开更多
The reactivation of pre-existing faults is a common phenomenon in a basin. This paper discusses the relationship between the pre-existing faults and the newly formed Coulomb shear fractures regarding pore fluid pressu...The reactivation of pre-existing faults is a common phenomenon in a basin. This paper discusses the relationship between the pre-existing faults and the newly formed Coulomb shear fractures regarding pore fluid pressures. Based on the Coulomb fracture criterion and Byerlee frictional sliding criterion, an equation relating pore pressure coefficient (λe), minimum dip angle (αe) of the reactive pre-existing fault and the intersection point depth (z) between the pre-existing fault and a newly formed Coulomb shear fault in an extensional basin, is established in this paper. This equation enhanced the understanding on the reactivation of pre-existing faults and can be used to calculate paleo-pore fluid pressures. The bigger the pore fluid pressure in a pre-existing fault is, the less the minimum dip angle for a reactive pre-existing fault will be. The minimum dip angle is less in shallow area than that in deep area. This will be of significance in petroleum exploration and development.展开更多
塔河油田奥陶系油气藏储层非均质性极强,烃源岩长期生排烃、多期充注成藏及混合改造,导致油气性质变化大,给流体识别带来巨大挑战。通过模型正演,分析缝洞型储层厚度、孔隙度、含流体性质对AVO特征的影响,明确气藏、轻质油藏、重质油藏...塔河油田奥陶系油气藏储层非均质性极强,烃源岩长期生排烃、多期充注成藏及混合改造,导致油气性质变化大,给流体识别带来巨大挑战。通过模型正演,分析缝洞型储层厚度、孔隙度、含流体性质对AVO特征的影响,明确气藏、轻质油藏、重质油藏三种不同类型油气藏的AVO特征及敏感参数;在此基础上,开展叠前反演,获得地下不同流体纵波阻抗及纵横波速度比特征,然后基于实际测井数据,建立三种不同类型油气藏岩石物理量版,在岩石物理量版指导下,利用双参数进行流体概率分析,获得缝洞储层流体定量识别结果。对塔河A区(气藏)、B区(轻质油藏)和C区(重质油藏),各50 km 2三维地震资料开展基于叠前AVO反演的流体识别应用研究,将识别结果用于盲井检验,气藏识别符合率为80%,轻质油藏符合率为76%,重质油藏符合率为72%。研究结果为塔河碳酸盐岩储层流体识别提供了参考依据。展开更多
基金Supported by National Basic Research Program of China(973 Program,Grant No.2012CB026006)
文摘The labyrinth seal in turbomachinery is a key element that restricts leakage flow among rotor-stator clearances from high-pressure regions to low-pressure regions. The fluid-induced forces on the rotor from seals during machine operation must be accurately quantified to predict their dynamic behavior effectively. To understand the fluid-induced force characteristics of the labyrinth seal more fully, the effects of four types of pre-swirls on the leakage, flow field, and fluid-induced force of a rotary straight-through labyrinth gas seal (RSTLGS) were numerically investigated using the proposed steady computational fluid dynamics (CFD) method based on the three-dimensional models of the RSTLGS. The leakage, flow field, and fluid-induced force of the RSTLGS for six axial pre-swirl velocities, four radial preswirl angles, four circumferential positive pre-swirl angles, and four circumferential negative pre-swirl angles were computed under the same geometrical parameters and operational conditions. Mesh analysis ensures the accuracy of the present steady CFD method. The numerical results show that the four types of pre-swirls influence the leakage, flow field, and fluid-induced force of the RSTLGS. The axial pre-swirl velocity remarkably inhibits the fluid-induced force, and the circumferential positive pre-swirl angle and circumferential negative pre-swirl angle remarkably promote the fluid-induced force. The effects of the radial pre-swirl angle on the fluid-induced force are complicated, and the pressure forces and viscous forces show the maximum or minimum values at a specific radial pre-swirl angle. The pre-swirl has a negligible impact on the leakage. The four types of pre-swirls affect the leakage, flow field, and fluidinduced force of the RSTLGS to varying degrees. The pre-swirl is the influence factor affecting the leakage, flow field, and fluid-induced force of the RSTLGS. The conclusions will help to understand the fluid-induced force of labyrinth seals more fully, by providing helpful suggestions for engineering practices and a theoretical basis to analyze the fluid–structure interaction of the seal-rotor system in future research.
文摘The reactivation of pre-existing faults is a common phenomenon in a basin. This paper discusses the relationship between the pre-existing faults and the newly formed Coulomb shear fractures regarding pore fluid pressures. Based on the Coulomb fracture criterion and Byerlee frictional sliding criterion, an equation relating pore pressure coefficient (λe), minimum dip angle (αe) of the reactive pre-existing fault and the intersection point depth (z) between the pre-existing fault and a newly formed Coulomb shear fault in an extensional basin, is established in this paper. This equation enhanced the understanding on the reactivation of pre-existing faults and can be used to calculate paleo-pore fluid pressures. The bigger the pore fluid pressure in a pre-existing fault is, the less the minimum dip angle for a reactive pre-existing fault will be. The minimum dip angle is less in shallow area than that in deep area. This will be of significance in petroleum exploration and development.
文摘塔河油田奥陶系油气藏储层非均质性极强,烃源岩长期生排烃、多期充注成藏及混合改造,导致油气性质变化大,给流体识别带来巨大挑战。通过模型正演,分析缝洞型储层厚度、孔隙度、含流体性质对AVO特征的影响,明确气藏、轻质油藏、重质油藏三种不同类型油气藏的AVO特征及敏感参数;在此基础上,开展叠前反演,获得地下不同流体纵波阻抗及纵横波速度比特征,然后基于实际测井数据,建立三种不同类型油气藏岩石物理量版,在岩石物理量版指导下,利用双参数进行流体概率分析,获得缝洞储层流体定量识别结果。对塔河A区(气藏)、B区(轻质油藏)和C区(重质油藏),各50 km 2三维地震资料开展基于叠前AVO反演的流体识别应用研究,将识别结果用于盲井检验,气藏识别符合率为80%,轻质油藏符合率为76%,重质油藏符合率为72%。研究结果为塔河碳酸盐岩储层流体识别提供了参考依据。
