Study on the Calculation Method of Gas Flow in Vacuum System Based on the Fluent Software

2010 ◽  
Vol 29-32 ◽  
pp. 1425-1429
Author(s):  
Shi Wei Zhang ◽  
Jin Ce Liu ◽  
Guang Zhe Song ◽  
Zhi Jun Zhang
Keyword(s):  
Laminar Flow ◽  
Calculation Method ◽  
Gas Flow ◽  
Volume Flow Rate ◽  
Fluid Velocity ◽  
Vacuum Field ◽  
Transitional Flow ◽  
Vacuum System ◽  
Continuity Hypothesis ◽  
Fluent Software

In order to improve the calculation method of the vacuum system design, the research focus on the way applying the Fluent software to calculation of gas flow in vacuum system in this paper. It is proved that the permission pressure lower limit is 1Pa for meeting the continuity hypothesis. The applicable flow patterns include turbulent flow, laminar flow and transitional flow between turbulent and laminar flow, which are totally defined as the viscous flow in the traditional vacuum field. By means of user define function (UDF), a layer mesh cell of negative quality source is defined to simulate the constant volume flow rate at the inlet of positive displacement vacuum pump, which makes up for the lack of compressible fluid velocity outlet boundary conditions in Fluent. The usability of Fluent in vacuum system is confirmed by a successful calculating example of gas flow in an ice condenser of vacuum freeze dryer.

scholarly journals Modeling of three-dimensional exciplex pumped fluid Cs vapor laser with transverse and longitudinal gas flow

2021 ◽  
Vol 9 ◽  
Author(s):  
Chenyi Su ◽  
Xingqi Xu ◽  
Jinghua Huang ◽  
Bailiang Pan
Keyword(s):  
Wall Temperature ◽  
Laser Power ◽  
Gas Flow ◽  
Particle Density ◽  
Fluid Velocity ◽  
Three Dimensional ◽  
Heat Accumulation ◽  
Vapor Laser ◽  
Output Laser Power ◽  
Output Laser

Abstract Considering the thermodynamical fluid mechanics in the gain medium and laser kinetic processes, a three-dimensional theoretical model of an exciplex-pumped Cs vapor laser with longitudinal and transverse gas flow is established. The slope efficiency of laser calculated by the model shows good agreement with the experimental data. The comprehensive three-dimensional distribution of temperature and particle density of Cs is depicted. The influence of pump intensity, wall temperature, and fluid velocity on the laser output performance is also simulated and analyzed in detail, suggesting that a higher wall temperature can guarantee a higher output laser power while causing a more significant heat accumulation in the cell. Compared with longitudinal gas flow, the transverse flow can improve the output laser power by effectively removing the generated heat accumulation and alleviating the temperature gradient in the cell.

Bifurcation analysis of two-dimensional laminar flow through sudden expansion channel

2022 ◽  
Vol 13 (1) ◽  
pp. 0-0
Keyword(s):  
Laminar Flow ◽  
Expansion Ratio ◽  
Sudden Expansion ◽  
Two Dimensional ◽  
Governing Equations ◽  
Bifurcation Phenomena ◽  
Different Types ◽  
Fluent Software ◽  
Flow Through ◽  
Volume Method

In this work, bifurcation characteristics of unsteady, viscous, Newtonian laminar flow in two-dimensional sudden expansion and sudden contraction-expansion channels have been studied for different values of expansion ratio. The governing equations have been solved using finite volume method and FLUENT software has been employed to visualize the simulation results. Three different mesh studies have been performed to calculate critical Reynolds number (Recr) for different types of bifurcation phenomena. It is found that Recr decreases with the increase in expansion ratio (ER).

Mass Transfer Enhancement for CO2 Absorption in Structured Packed Absorption Column

2019 ◽  
Vol 41 (5) ◽  
pp. 820-820
Author(s):  
Pongayi Ponnusamy Selvi and Rajoo Baskar Pongayi Ponnusamy Selvi and Rajoo Baskar
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Gas Flow ◽  
Aqueous Ammonia ◽  
Volume Flow Rate ◽  
Packed Column ◽  
Operating Conditions ◽  
Co2 Absorption ◽  
Absorption Column

The acidic gas, Carbon dioxide (CO2) absorption in aqueous ammonia solvent was carried as an example for industrial gaseous treatment. The packed column was provided with a novel structured BX-DX packing material. The overall mass transfer coefficient was calculated from the absorption efficiency of the various runs. Due to the high solubility of CO2, mass transfer was shown to be mainly controlled by gas side transfer rates. The effects of different operating parameters on KGav including CO2 partial pressure, total gas flow rates, volume flow rate of aqueous ammonia solution, aqueous ammonia concentration, and reaction temperature were investigated. For a particular system and operating conditions structured packing provides higher mass transfer coefficient than that of commercial random packing.

scholarly journals Biofilm physical structure, internal diffusivity and tortuosity

2005 ◽  
Vol 52 (7) ◽  
pp. 77-84 ◽  
Author(s):  
L.F. Melo
Keyword(s):  
Laminar Flow ◽  
Research Group ◽  
Fluid Velocity ◽  
Physical Structure ◽  
Flow Conditions ◽  
Physical Concept ◽  
Common Trend ◽  
Effective Diffusivities ◽  
Biofilm Structure ◽  
Turbulent Flow Conditions

The paper proposes tortuosity as a physical concept particularly useful to interpret internal diffusivities in terms of biofilm structure. Results from different authors are presented showing how average effective diffusivities in biofilms (measured with inert tracers) vary with the fluid velocity: in the case of biofilms formed under turbulent flow conditions, an increase in fluid velocity corresponds to a decrease in the diffusivity, although sometimes this decrease is very slight; however, in laminar flow situations, no common trend is found from research group to research group.

scholarly journals NMR Analysis Method of Gas Flow Pattern in the Process of Shale Gas Depletion Development

Geofluids ◽  
2022 ◽  
Vol 2022 ◽  
pp. 1-7
Author(s):  
Rui Shen ◽  
Zhiming Hu ◽  
Xianggang Duan ◽  
Wei Sun ◽  
Wei Xiong ◽  
...  
Keyword(s):  
Flow Pattern ◽  
Pore Pressure ◽  
Shale Gas ◽  
Gas Flow ◽  
Continuous Medium ◽  
Slip Flow ◽  
Flow Patterns ◽  
Transitional Flow ◽  
Analysis Method ◽  
Adsorbed Gas

Shale gas reservoirs have pores of various sizes, in which gas flows in different patterns. The coexistence of multiple gas flow patterns is common. In order to quantitatively characterize the flow pattern in the process of shale gas depletion development, a physical simulation experiment of shale gas depletion development was designed, and a high-pressure on-line NMR analysis method of gas flow pattern in this process was proposed. The signal amplitudes of methane in pores of various sizes at different pressure levels were calculated according to the conversion relationship between the NMR T 2 relaxation time and pore radius, and then, the flow patterns of methane in pores of various sizes under different pore pressure conditions were analyzed as per the flow pattern determination criteria. It is found that there are three flow patterns in the process of shale gas depletion development, i.e., continuous medium flow, slip flow, and transitional flow, which account for 73.5%, 25.8%, and 0.7% of total gas flow, respectively. When the pore pressure is high, the continuous medium flow is dominant. With the gas production in shale reservoir, the pore pressure decreases, the Knudsen number increases, and the pore size range of slip flow zone and transitional flow zone expands. When the reservoir pressure is higher than the critical desorption pressure, the adsorbed gas is not desorbed intensively, and the produced gas is mainly free gas. When the reservoir pressure is lower than the critical desorption pressure, the adsorbed gas is gradually desorbed, and the proportion of desorbed gas in the produced gas gradually increases.

Laminar and transitional flow of drilling muds and various suspensions in circular tubes

1967 ◽  
Vol 30 (3) ◽  
pp. 449-464 ◽  
Author(s):  
Bernard Le Fur ◽  
Madeleine Martin
Keyword(s):  
Reynolds Number ◽  
Laminar Flow ◽  
Rheological Behaviour ◽  
Simple Expression ◽  
Transitional Flow ◽  
Transition Flow ◽  
Flow Rates ◽  
Circular Tubes ◽  
Head Losses ◽  
Drilling Muds

Most suspensions exhibit a rheological behaviour which cannot be represented by either Bingham's or Ostwald–De Waele's law. In studying such cases a very simple expression with only three parameters may be used. Starting with an intermediate law of this sort, this paper gives velocity profiles and head losses in laminar flow, which have been computed and plotted on diagrams in non-dimensional co-ordinates.It has been found that transition flow rates in circular tubes for data taken from the literature and from experiments conducted on drilling muds at the Institut Français du Pétrole, are efficiently predicted by an empirical criterion (Ryan & Johnson 1959) which establishes a relation between a generalized Reynolds number and a generalized Hedström number.

scholarly journals Analysis of the Effect of Anode Porosity on Temperature Distribution on Planar Radial Type SOFC

2018 ◽  
Vol 73 ◽  
pp. 01010
Author(s):  
Alif Widiyanto ◽  
Sulistyo ◽  
MSK Tony Suryo Utomo
Keyword(s):  
Temperature Distribution ◽  
Gas Flow ◽  
Hydrogen Gas ◽  
Cfd Modeling ◽  
Dynamics Modeling ◽  
Waste Products ◽  
Geometry Model ◽  
Electrolyte Surface ◽  
Fluent Software ◽  
Object Of Study

Solid Oxide Fuel Cell (SOFC) is an electrochemical equipment that converts gas into electricity directly. The waste products resulting from SOFC are water vapor and heat when using hydrogen gas. The electrode of the SOFC is the anode, electrolyte and cathode. The performance of SOFC is influenced porosity of the electrode. This study explained the relationship between porosity of the anode and temperature distribution using computational fluid dynamics modeling approach (CFD). In this study, CFD modeling was done by using Fluent software. The geometry model of computational modeling is a planar radial-type SOFC. The assumptions of some boundary conditions used from the study of literature and the object of study. The standard deviation and the different of temperature of the anode-electrolyte surface used to analyse the result. Non-homogenous temperature distribution rise if the anode porosity and gas flow rate is increasing. This indicates the gradient of temperature is bigger in the higher porosity, which may cause thermal stress and degrades the materials of electrode.

scholarly journals Thermal Diffusion Performance of a Diffuser by various Guide Vanes configurations

2018 ◽  
Vol 225 ◽  
pp. 03018
Author(s):  
Aja O. Chikere ◽  
Hussain H. Al-Kayiem ◽  
Zainal Ambri A. Karim
Keyword(s):  
Gas Flow ◽  
Cfd Simulation ◽  
Bench Mark ◽  
Ansys Fluent ◽  
Guide Vanes ◽  
Pressure Losses ◽  
Fluent Software ◽  
Thermal Diffuser ◽  
Crosssectional Area ◽  
Large Diffusion

The use of vane-less diffuser with large diffusion angle has shown a setback in the diffusion process of high temperature working fluids. The hot gas flow was characterized as a jet-like flow. This paper presents problem, encountered practically, using a vane-less diffuser with large diffusion angle and how the problem is solved by CFD simulation. The investigated thermal diffuser has a length of 0.3 m, an inlet to outlet crosssectional area ratio of 1:25 and diffusion angle of 115.44o. To resolve the jet-like flow problem and poor distribution of the flow temperature at the diffuser outlet, the study suggested the use of guide-vanes into the diffuser. The study employed CFD simulation by ANSYS-FLUENT software to analyze the flow and thermal process in the diffuser. Three different shapes of guide vanes; block-shaped, oval-shaped and airfoil-shaped were considered in this study and at different vanes diffusion angles, as well as vane-less case, which was adopted as the bench mark case. The simulation results of the velocity, temperature and pressure at the diffuser outlet were compared for all cases. It was found that the guide vanes with symmetrical airfoil profile provided the best performance with most uniform distribution at the outlet of the diffuser. Also, the airfoil-shaped guide vanes resulted in lower pressure losses compared to the block-shaped and oval-shaped guide vanes. According to the analysis results, the diffuser was redesigned to improve the diffusion and temperature distribution across the diffuser outlet.

Experimental Investigations of Laminar, Transitional to Turbulent Gas Flow in a Micro-Channel

2010 ◽  
Author(s):  
Chungpyo Hong ◽  
Toru Yamada ◽  
Yutaka Asako ◽  
Mohammad Faghri ◽  
Koichi Suzuki ◽  
...  
Keyword(s):  
Mach Number ◽  
Flow Regime ◽  
Gas Flow ◽  
Flow Characteristics ◽  
Channel Length ◽  
Transitional Flow ◽  
Experimental Investigations ◽  
Compressibility Effect ◽  
Micro Channels ◽  
Wide Range

This paper presents experimental results on flow characteristics of laminar, transitional to turbulent gas flows through micro-channels. The experiments were performed for three micro-channels. The micro-channels were etched into silicon wafers, capped with glass, and their hydraulic diameter are 69.48, 99.36 and 147.76 μm. The pressure was measured at seven locations along the channel length to determine local values of Mach number and friction factor for a wide range of flow regime from laminar to turbulent flow. Flow characteristics in transitional flow regime to turbulence were obtained. The result shows that f·Re is a function of Mach number and higher than incompressible value due to the compressibility effect. The values of f·Re were compared with f·Re correlations in available literature.

Sign in / Sign up

Export Citation Format

Share Document