Papers by Keyword: Two Phase

Abstract: The purpose of this research is to better understand the characteristics of two-phase flow in a rectangular bubble column. Computational Fluid Dynamics (CFD) (ANSYS-FLUENT R15.0®) has been used to conduct numerical studies of the flow pattern. Furthermore, the experimental data is used to verify the accuracy of the numerical data. This unique CFD simulation research included a 3D system, Reynolds-Average, Navier-Stokes equations (RANS), k-turbulence model, and total interphase forces. Bulk flow patterns were revealed through CFD analysis. Total contact force, both constant and non-steady, is also analyzed for its impact. The data show liquid upflow in the column's bulk section and liquid downflow near the wall. In the gas phase, bubbles rose in the middle area and departed the bed. In addition, bubbles without enough velocity to leave the bed circulate towards the wall with liquid and follow a similar pattern. The results show that the phenomenon of the central peak can only be captured by using a single bubble and no drag forces. The correlation between simulation and experimental findings is excellent. Within the higher, middle, and nearby gas distributor height ranges, the outcome agrees extremely well with the experiment. In addition, the results of the experiments show that the level of turbulence has played a crucial role in dynamic behavior. The CFD model described qualitative and quantitative flow performance, producing excellent results. The results also gave a framework for comparing and evaluating future designs and gave insights into the fluid dynamics of the bubble column reactor. Efforts were made to compare and contrast the main operating modes of different reactor designs. Keywords: Two phase, Ansys, Bubble column, CFD, Drag force, Flow Pattern.

Abstract: Along with the development of simulation technology, systems of three-dimensional simulation are being used in more and more domains. The distance of objects is one of the important measures which are used to estimate the relationship of object’s position and to weigh the attributes of their own movement. The distance computing places an important role in the system of 3D simulation. In this paper, the two-phases (broad-phase and narrow-phase) algorithm for computing distance is presented. Using the algorithm, finally we have got the minimum distance of objects, and the feasibility and veracity of the algorithms are proved by an example.

Abstract: Level Set Method is an appropriate mathematical tool for solving two-phase flow problems. The main advantage of Level Set Method is its efficiency to deal with complex interfaces, even if topology changes. In this paper, the liquid-gas two-phase flow is simulated using a combination of Level Set Method and SOLA method. SOLA is used to compute the Navier-Stokes equation, and Level Set Method is used to track the interfaces between the liquid and the gas during mold filling process. The difficulty in the simulation of two-phase flow comes from great change of physical parameters (e.g., density and viscosity) across the interfaces. Level Set Method allows for large density ratio and jump in viscosity without reconstructing the numerical grid. In this work, the forming and moving of the gas bubbles in liquid were numerically simulated by Level Set approach. The numerical simulation results and experiments suggest that Level Set Method is quite reliable and effective for the simulation of liquid-gas two-phase flow during mold filling.

Abstract: In the present paper the effect of heat treatment on microstructure, martensitic transformation temperatures and magnetic properties behavior of Co-Ni-Ga pollycrystal was discussed in detail. Microscopic observations revealed two types of two phase polycrystalline alloys: i) martensite with γ-precipitates and ii) parent phase with γ-precipitates. Making use of Xray and electron diffraction methods the crystal structure of martensite phase was identified as bct structure (with co/ao about 1.2). Annealing of Co-Ni-Ga alloy at 1223K/40 min causes a separation of martensitic and magnetic transformation and an increase of the Curie temperature by about 70K, after this annealing any significant structural changes in the parent (martensitic) and γ phase are not observed.

Abstract: The high temperature deformation mechanisms of two phase a+b alloy and a near-a alloy were investigated, and compared within the framework of inelastic-deformation theory. For this purpose, load-relaxation tests were conducted on the two alloys at temperatures of 750~900°C. The flow stress-vs.-strain rate curves for both alloys were well fit with inelastic deformation equations describing dislocation glide and grain boundary sliding. The amount of grain boundary sliding resistance was higher in the near-a alloy rather than the two phase a+b alloy due to difficulty in stress relaxation at triple junction region.