Papers by Keyword: Pressure Field

Abstract: According to the Darcy - Stokes equations of fractured-vuggy porous medium, using COMSOL Multiphysics software, we calculated several typical conceptual model pressure field distribution, analyzed the influence of fractured-vuggy porous medium internal vug and fractured geometric configuration on the pressure field in the model.

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: Patterns of velocity and pressure field formation inside the cyclone apparatus have been revealed. Also, the standard k-turbulence model for the study of aerodynamic processes in centrifugal dust collectors has been adapted A high degree of adequacy of the results is shown. Using the proposed model, taking into account vortex air flow processes forming the velocity and pressure fields in the body of cyclone apparatuses are described.

Abstract: A comparative study on pressure field of hydrostatic thrust bearing with sector recess, rectangular recess, ellipse recess and I-shaped recess is carried out in order to solve the deformation of the hydrostatic thrust bearing. The Finite Volume Method has been used to compute three-dimensional pressure field of gap oil film between the rotation worktable and the base. This study theoretically analyzes the influence of recess shape on the bearing pressure characteristic according to Computational Fluid Dynamics (CFD) and lubricating theory. It has revealed its pressure field distribution law. The simulation results indicate that an improved characteristic will be affected by recess shape easily. Through this method, the safety of a hydrostatic thrust bearing with different recesses can be forecasted, and the optimal design of such products can be achieved, so it can provide reasonable data for design, lubrication, and experiment and deformation computation for hydrostatic thrust bearing.

Abstract: Large size hydrostatic bearing is the core component of heavy CNC equipment. The influence of pressure, heating and running time can reduce film thickness during operation. This will directly affect machining accuracy and operation reliability of the entire machine. Aiming at the problem of influence of rotational velocity on carrying capacity of heavy hydrostatic bearing, use finite volume method (FVM) to simulate gap film pressure field of heavy hydrostatic bearing with Constant Flow and study pressure field distribution law on the conditions of the different rotational velocity and same cavity depth, oil cavity area, then optimize oil cavity structure. Results show that, pressure field distribution law of the different rotational velocity is basically identical, but its carrying capacity is different. From the relation curve of the pressure and rotational velocity can be seen, because of the dynamic pressure of existence, along with the increase of rotational velocity, carrying capacity gradually. The study is of vital theoretical significance for the improvement of machining accuracy of numerical control machine and the entire CNC equipment and provides valuable theoretical basis for the design of hydrostatic guide rail in engineering practice.

Abstract: For DVT500 vertical lathe of the carrying capacity of heavy hydrostatic bearing problem, Through the simplification of the geometric model of a single oil pad to derive the effective bearing area of a single oil pad, then establish its mathematical model, for the following to prepare for the simulation of heavy hydrostatic bearing, and through the simulation of heavy hydrostatic bearing, get the input under the condition of unchanged, with the constant improvement of the speed, the change of heavy hydrostatic bearing pressure field. Results show that the feed quantity under the condition of unchanged, with the constant improvement of the speed, start from the center of the biggest oil cavity pressure peak around gradually diminishing, isobar and high oil and shape of cavity shape basically the same. Numerical calculation results reflect the inside of the bearing pressure distribution, the simulation results for the engineering practice the bearing oil cavity structure optimization design provides a theoretical basis.

Abstract: A numerical simulation for flow field in water-lubricated guide bearing of large tubular pump is conducted by software Fluent, which shows the pressure distribution of water film with different rotating speeds and the rule of the influence of relevant parameters on the amount of lubricating water, dynamic and static characteristics of guide bearing.The result shows that the pressure distributions of water film at low and high speeds are very different, and with the obvious dynamic pressure effect, the bearing inner can be in a state of reflux and the water-lubricated amount and clearance are reduced. The load capacity and stiffness of guide bearing are increased along with the speed and water pressure increase meanwhile the amount of water is increased along with the speed lowering and the water pressure and clearance increase.

Abstract: For cooperating with automation of flow measurement in irrigation districts, the method of flow measurement needs to be improved. Considering that sedimentation may appear at most channels and comparing with common water measure equipment, cutthroat flume measuring flume become the most suitable flow measurement structure adopted in irrigation districts with the advantages of the simple structure, the lower upstream backwater, not easy to silt the flume and so on. In the background of the cutthroat flume of one channel in the Ye River irrigation district of Shijiazhuang and on the basis of RNG k-εturbulence model, the 3-D numerical simulation of the flow field of cutthroat flume is carried out to obtain the distribution of velocity field and pressure field. By comparing the calculation value of nodal velocity with the measured value of nodal velocity, the reliability of the result of numerical simulation is proved. The above conclusions provide theoretical basis for further optimization design of cutthroat flume.

Abstract: In order to study the flow field characteristics around perforating well eyeholes, using the finite element method, it utilize actual physical property, establish the geometric model, through the grid partition and post-processing, got the velocity field and pressure field cloud chart, and analysis the data of controlled, got the mobility pattern of the flow field of around eyeholes. Through three of different eyehole deep using the same physical parameters for modeling analysis, the influence of different eyehole depth of flow field around the holes is got. Through the contrast simulated results of perforating completion heat flow model with the exact solution of open hole completion, the result reveals the specialty and the regular pattern of perforating completion flow field. Meanwhile, according to the theory of water and electricity similar, the actual physical model of perforating completion electric analogue is made and actual the pressure field distribution around eyeholes is measured. The results agree with the results of ANSYS heat flow field simulation. This verify the correctness of the ANSYS analysis. Research shows that using heat flow field module of ANSYS simulation seepage field to serve research seepage field of well is a kind of general method.

Abstract: In order to solve the mechanical deformation of the hydrostatic center rest, a numerical simulation concerning pressure field of hydrostatic center rest is studied. CFX of ANSYS has been used to compute three-dimensional pressure field of gap fluid between workpiece and bearing pillow. This research analyzes the influence of rotation speed on the bearing pressure performance according to lubricating theory and computational fluid dynamics, and it has revealed its pressure distribution law of gap oil film. Results indicate that an improved characteristic will be affected by rotation speed easily, and oil cavity pressure increases by gradually with rotation speed enhancing. The reliability of a hydrostatic center rest can be predicted through this method.