Modeling of Slug Velocity and Pressure Drop in Gas‐Liquid‐Liquid Slug Flow

Gas‐liquid‐liquid slug flow in a capillary reactor is a promising new concept that allows one to incorporate gas‐liquid reaction, liquid‐liquid extraction, and facile catalyst separation in a single unit. In order to assess the performance of a gas‐liquid‐liquid slug flow reactor, it is necessary to predict the slug velocity and pressure drop to ascertain residence times and reaction rates. New empirical models for velocity and pressure drop were developed based on existing models for two‐phase gas‐liquid and liquid‐liquid slug flows, and these were validated experimentally.     

Flow Compartments in Viscoelastic Fluids Using Radial Impellers in Stirred Tanks

The influence of viscoelastic flow properties on fluid dynamics using radial impellers is investigated. The use of transparent model fluids allows for the optical measurement of general flow behavior with a fluorescence dying technique. By varying viscoelastic flow properties, size of agitators and rotational frequency, the impact of these parameters on fluid dynamics is analyzed. Toroidally shaped, cavern‐like flow compartments form around the agitators in all fluids in specific rotational frequency ranges, preventing an efficient mixing. By balancing elastic with centrifugal forces, a simple model is developed with which compartment sizes can be predicted with good accuracy. The results indicate a good suitability of the elasticity number as a scale‐up criterion.     

Motion control of underactuated linkage robot based on gymnastic skill

In this paper, a reproduction of a swing‐up and a giant swing motion of underactuated robots based on technique of the horizontal bar gymnast is discussed with focusing on an equivalent center of mass (ECM) of underactuated robots and the gymnast. At first, the behaviors of the ECM of the gymnast (ECMG) are analyzed by using a motion capturing technique and an efficient motion of the ECMG for the swing‐up and for the giant swing motion are identified from analysis results, respectively. Next, a partial linearization method, which can realize that the ECM of the Acrobot (ECMA) replicates this efficient motion, is designed and reproduces the underactuated robots the swing‐up and giant swing motion like the gymnast. Finally, an effectiveness of the proposed controller is shown by numerical simulations.     

The residual zonal flow in tokamak plasmas with a poloidal electric field

In a tokamak plasma with auxiliary heating by cyclotron waves, a poloidal electric field will be produced, and as a consequence influence the residual zonal flow(RZF) level. The poloidal electric field can also be induced through biasing electrodes at the edge region of tokamaks.Numerical evaluation for a large aspect ratio circular cross section tokamak for the electron cyclotron wave heating indicates that the RZF level decreases significantly when the poloidal electric field increases. Qualitatively, the ion cyclotron wave heating is able to increase the RZF level. It is difficult to apply the calculation to the real cyclotron wave heating experiments since we need to know factors such as the plasma profiles, the exact power deposition and the cross section geometry, etc. It is possible to use the cyclotron wave heating to control the zonal flow and then to control the turbulence level in tokamak experiments.     

Imaging the Curie Point isothermal surface and predicting its impact on the geothermal regime within the Nile Delta,Egypt

The available aeromagnetic data together with information from some available wells have been used in the current study to shed the light on the geothermal setup of the Nile Delta Province. The aeromagnetic data was reduced-to-pole and critically analyzed using the Spectral Analysis Technique through the Fast Fourier Transform (FFT), to determine the expected depths to the Basement and Curie Point (CPD) surfaces. The geothermal gradient between CPD and earth's surface was estimated, and accordingly the heat flow was evaluated using the proposed thermal conductivity. Then, the Basement Surface Temperature (BST) was estimated, by which the geothermal gradient and heat flow for the igneous-rocky basement and sedimentary-rocky horizon was independently predicted. By which, it could be possible to distinguish between the heat flow contribution from each horizon separately.     

水平井筒气水流动规律及影响因素

由于流动方向变化及壁面流体的不断径向入流，水平井筒的气水流动规律与常规直井存在较大差异。在总结前人研究结果的基础上，优选水平井筒气液两相预测模型，并在验证模型可靠的情况下，考虑管壁入流和气液流型变化，改变气量、水量、管径、倾角、轨迹波动、气水入流位置等多个影响因素，对水平段流型、压力分布规律及影响因素进行综合预测分析，为水平气井的生产管理及后期措施优化提供依据。研究结果表明，一般生产条件下水平井筒存在分层流、间歇流和环雾流3种流型，管径和倾角对水平井筒的气、水流型影响最为明显，管壁入流对入流就地井筒流态的影响较小。水平井筒压力损失与气量、水量、轨迹上倾角及轨迹波动起伏程度呈正相关性，而与管径和下倾角呈负相关性。预测范围内，气量、轨迹上倾和管径对水平井筒压力损失的影响最为明显，是水平井筒压降的关键影响因素。随着轨迹上倾角增加，水平井筒压降随气量的变化规律发生明显反转，低气量条件下水平井筒压降随气量的减小而增加，高气量下压降随气量增加而增加。     

环形通道内液态铅铋合金流动换热特性实验研究

通过对环形通道内液态铅铋合金的流动换热特性进行实验研究，得到了气泡泵注气对液态金属流动的影响，并拟合出环形通道内液态铅铋合金的摩擦系数关系式和换热特性关系式。结果表明：采用气泡泵注气能有效提升铅铋合金的质量流速；相同Reynolds数下环形通道内液态铅铋合金的摩擦系数大于由布拉休斯公式计算得到的摩擦系数；液态铅铋合金对流换热过程中，导热项占主导地位，并且Nusselt数随Peclet数的增大而增大。     

MHD flow in a rectangular duct with a perturbed boundary

The unsteady magnetohydrodynamic (MHD) flow of a viscous, incompressible and electrically conducting fluid in a rectangular duct with a perturbed boundary, is investigated. A small boundary perturbation $\epsilon$ is applied on the upper wall of the duct which is encountered in the visualization of the blood flow in constricted arteries. The MHD equations which are coupled in the velocity and the induced magnetic field are solved with no-slip velocity conditions and by taking the side walls as insulated and the Hartmann walls as perfectly conducting. Both the domain boundary element method (DBEM) and the dual reciprocity boundary element method (DRBEM) are used in spatial discretization with a backward finite difference scheme for the time integration. These MHD equations are decoupled first into two transient convection–diffusion equations, and then into two modified Helmholtz equations by using suitable transformations. Then, the DBEM or DRBEM is used to transform these equations into equivalent integral equations by employing the fundamental solution of either steady-state convection–diffusion or modified Helmholtz equations. The DBEM and DRBEM results are presented and compared by equi-velocity and current lines at steady-state for several values of Hartmann number and the boundary perturbation parameter.