Papers by Keyword: Velocity Field

Abstract: Currently, mathematical modeling applying numerical methods is widely used in the study of metallurgical processes, including metal casting processes in continuous-casting machines. The authors developed a new technology and device for casting metal into a continuous-casting machine mold and metal mixing using the effect of a rotating closed-bottom submerged nozzle with eccentric holes. The theoretical study of processes of mold filling with molten metal was carried out applying a proven numerical method and a special software package. A calculation program was developed based on the numerical schemes and algorithms. The results of calculating metal casting into a rectangular mold are presented as an example. The calculation results are provided in the form of molten metal flow patterns in various sections of the mold.

Abstract: Mathematical modeling of plastic deformations in rolling consists in a consequent combination of the general energetic relationship in plasticity and the variation inequality expressed the principle of minimum of entire deformation energy. A real deformation state in a plastic zone beneath rolls and corresponding kinematic and dynamics conditions on the contact surface are considered as a limited one for the consequent approximate deformation states and are found out by the method of approximated approach. Any realization of this method on personal computers requires a rational construction of a kinematic-possible velocity field in the spatial domain on plastic flow. Using the ordinary propositions and a new assumptions the authors have constructed a simple kinematic-possible velocity field in the plastic zone beneath rolls. On the base of the consequent approach in which the general energetic relationship and the variation inequality are interrelated the authors have been able to find out the geometric, kinematic and dynamics characteristics of plastic deformation’s states in metal rolling.

Abstract: This study uses the dies of the dray fasteners processing graphics provided by the fastener’s industry to establish 3D dies and components solid models based on the embedded drawing function tools provided by the component model (Standard.ipt) of Autodesk Inventor CAD software. After finishing the dies and components drawing, the integrated assembly drawing of dies can be obtained through the assembly model (Standard.iam) firstly. Three stages forming processes can be conducted and carried out the FEM simulation to check the forming acceptance. The effective stress, the effective strain, the velocity field, and the forging force can be obtained by the FEM simulation. Moreover, the realistic experiment can be performed to verify the acceptance of FEM simulation. The dimensions of final product can be measured to get the errors between FEM and experiment. It is noted that the errors show a good agreement with the experiment.

Abstract: A robust model for calculating the necessary process variables such as strain, strain rate and temperature in hot rolling of a steel plate or strip is presented in this paper. The applied approach includes a well-constructed velocity function in the deformation model that is validated using a commercial finite element solver. The developed microstructure model is then integrated into the process model and includes the most essential descriptions of restoration and austenite grain structure evolution phenomena during hot rolling. Furthermore, the concept of hierarchical grain structure evolution is described as a method track the evolution of un-recrystallized and recrystallized features of the microstructure throughout a given pass schedule. The most important outcome of this approach is that each grain size component is modelled separately based on its prior thermomechanical history. A computer implementation of these models called MICDEL is used together with a simulation example to demonstrate its capability of predicting process variables and austenite grain structure evolution in hot strip rolling of steel.

Abstract: The sancha river mouth is located at the intersection of qinhuai river and Yangtze river. The flow movement of sancha River mouth are affected by application of sancha river gate and Yangtze River. The flow characteristics of the river mouth is very complex. The numerical simulation is used to study the flow movement. The 2-D depth-averaged mathematical model has been established. The govering equations and numerical simulation of flow movement are given in the boundary-fitting orthogonal coordinate systems. The model verification has done by the field data. The flow movement are computed for different application mode of sancha river gate and Yangtze river level. The mainstream line variation and local inverse flow are analyzed for the sancha river mouth.

Abstract: An increase of a combustion chamber volume of internal combustion engines (ICE) is connected with the solution of a problem of burning in cylinders of bigger amount of fuel. Thus, providing the complete burning, a full scavenging of cylinders and maintenance in permissible limits of temperature of exhaust gases requires increasing air supply. The most effective method of increase in amount of air is an increase of its density by means of preliminary compression in the compressor with the subsequent cooling. It should be noted that high complexity and a large labor content of the natural experiments do not allow receiving the reliable values of gas-dynamic characteristics of air flow in a compressor of a turbocharger. Therefore, by means of a computer code of computational fluid dynamics ANSYS-CFX, numerical studies of a flow in gas channel of a compressor of the KAMAZ engine are carried out. The integrated values of pressure, temperature in inlet and outlet of a compressor, received during numerical simulations, allow defining the air compression ratio, and also calculating compressor efficiency. Verification of the results of the numerical studies and of the natural experiment gives an agreement of the values with accuracy 1-5%. Hereafter, analysis of the calculation results, and optimization of the gas channel geometry of the compressor can allow improving gas-dynamic parameters of the compressor. This can lead to raise in techno-economic characteristics of the ICE.

Abstract: The Chinese refrigeration industry is faced with dual pressure of energy saving and emission reduction. R600a as an alternative refrigerant of R134a is environment friendly, and the alternation is very good. Firstly, this paper established a two-dimensional steady numerical calculation model of the refrigerating chamber with R600a, and studied the influence of the temperature distribution of the refrigerator’s posterior wall under different schemes on temperature field and velocity field of the refrigerating chamber. When the function of temperature distribution is T=-11.75*y, will achieve the best temperature field and velocity field, and the results are better than the original machine. Secondly, this paper studied the experimental improvement of R600a under the best temperature distribution scheme comparing with R134a.

Abstract: The vertical panels of solar chimney have internal dimensions of 2000mm height、1000mm length. Under the condition of heat flux and chimney gap variety, we research chimney interior velocity field. Experimental Results show that airflow increased with chimney gap augmentation, the airflow and air velocity augment with the increase of solar radiant intensity, and air velocity decreases with the increase of solar chimney gap. Air velocity is higher near the heated surfaces than it in the middle chimney. Meanwhile velocity boundary layers form near the heated surface.

Abstract: The velocity field and the associated tangential tension corresponding to the flow of the viscoelastic fluid over an infinite rigid plate are determined in this paper. The characteristic of the non-Newtonian viscoelastic fluid flow is analyzed using the Stehfest method of the numerical inversion of Laplace transform. It indicates that the flow of the viscoelastic fluid is very sensitive to the material constants. Finally, some comparative diagrams concerning the velocity and tangential tension profiles are presented.

Abstract: On basis of two-phase flow and the heat transfer theory, the velocity and temperature of the liquid lend-bismuth eutectic were calculated with gas-injection and without gas-injection by FLUENT code, in the calculation segment. The radial velocity profiles and temperature profiles were acquired at different cross section. Analysis results show that: no matter the argon is existence or not, the velocity distribution and the temperature distribution have a good symmetry. Temperature rise of the liquid lend-bismuth eutectic with gas injected is larger than without argon. It is shown that the gas-injection is good for heat transfer of liquid lend-bismuth in the calculation segment.