scholarly journals Неизотермическое течение газа в эллиптическом канале с внутренним круговым цилиндрическим элементом в свободномолекулярном режиме

2019 ◽  
Vol 89 (1) ◽  
pp. 27
Author(s):  
О.В. Гермидер ◽  
В.Н. Попов
Keyword(s):  
Mass Flow ◽  
Basic Equation ◽  
Gas Flow ◽  
Diffuse Reflection ◽  
Boltzmann Kinetic Equation ◽  
Molecular Gas ◽  
Pressure Drops ◽  
Reflection Model ◽  
Linearized Problem ◽  
Temperature And Pressure

AbstractThe linearized problem of free-molecular gas flow in a long elliptic channel with a circular cylindrical element inside has been solved in the kinetic approximation. The flow in the channel is caused by temperature and pressure drops between its ends. The Boltzmann kinetic equation for collisionless gas has been used as a basic equation, and the boundary condition has been set in terms of the diffuse reflection model. The distribution of the mass velocity of the gas over the cross section of the channel has been obtained. The mass flow rate of the gas in the channel versus the temperature and pressure drops between its ends has been calculated. It has been found that the mass flow of the gas substantially depends on the radius of the inner cylinder.

scholarly journals A collocation method for the Williams equation with Chebyshev polynomials

2021 ◽  
Vol 2056 (1) ◽  
pp. 012005
Author(s):  
O V Germider ◽  
V N Popov
Keyword(s):  
Collocation Method ◽  
Chebyshev Polynomials ◽  
Basic Equation ◽  
Gas Flow ◽  
Diffuse Reflection ◽  
Constant Pressure ◽  
Plane Channel ◽  
Reflection Model ◽  
Linearized Problem ◽  
The Given

Abstract The linearized problem of gas flow in plane channel with infinite walls has been solved in the kinetic approximation. The flow in the channel is caused by a constant pressure gradient parallel to the walls of the channel. The Williams equation has been used as a basic equation, and the boundary condition has been set in terms of the diffuse reflection model. The collocation method for Chebyshev polynomials has been applied to construct the solution of the equation of Williams with the given boundary conditions. The mass flux of the gas in the channel has been calculated.

scholarly journals Analytical solution to the problem of diffusion of the light component of the binary gas mixture in a plane channel

2021 ◽  
Vol 2056 (1) ◽  
pp. 012004
Author(s):  
V N Popov ◽  
I V Popov
Keyword(s):  
Analytical Solution ◽  
Flow Rate ◽  
Diffuse Reflection ◽  
Plane Channel ◽  
Boltzmann Kinetic Equation ◽  
Heavy Component ◽  
Light Component ◽  
Reflection Model ◽  
Binary Gas Mixture ◽  
Gas Component

Abstract Within the framework of the kinetic approach, an analytical solution to the problem of diffusion of the light component of a binary mixture in a flat channel with infinite parallel walls is constructed. It is assumed that the mass of light component molecules and their concentration is much less than the mass of molecules and the concentration of heavy components. The flow rate of the heavy component is assumed to be zero. The change in the state of a light gas component is described on the basis of the BGK (Bhatnagar, Gross, Kruk) model of the Boltzmann kinetic equation. The diffuse reflection model is used as a boundary condition on the channel walls. The mass velocity profile of the light gas component is constructed. The flow rate of the light gas component per unit channel width is calculated. A comparison with similar results presented in open sources was done.

Losses in the inlet path of a two-rotor vacuum pump

2021 ◽  
pp. 44-46
Author(s):  
Keyword(s):  
Mass Flow ◽  
Gas Flow ◽  
Vacuum Pump ◽  
Flow Coefficient ◽  
Numerical Calculations ◽  
Ansys Fluent ◽  
Pressure Drops ◽  
Rotor Rotation ◽  
Pump Inlet ◽  
Good Agreement

A model of the inlet path of a two-rotor vacuum pump of the Roots type is developed. In the Ansys Fluent package, numerical calculations of the gas flow in the inlet path were carried out at various inlet pressures, pressure drops and rotor rotation angles. The obtained gas mass flow coefficients are in good agreement with the experimental ones. Keywords: two-rotor vacuum pump, inlet path, mass flow coefficient, CFD. [email protected]

Effect Of Equivalent Ratio (ER) On the Flow and Combustion Characteristics in A Typical Underground Coal Gasification (UCG) Cavity

2021 ◽  
Vol 86 (2) ◽  
pp. 28-38
Author(s):  
Arup Kumar Biswas ◽  
Wasu Suksuwan ◽  
Khamphe Phoungthong ◽  
Makatar Wae-hayee
Keyword(s):  
Mass Flow ◽  
Flow Rate ◽  
Gas Flow ◽  
Coal Gasification ◽  
High Efficiency ◽  
Combustion Characteristics ◽  
Raw Material ◽  
Underground Coal Gasification ◽  
Equivalent Ratio ◽  
Rubble Pile

Underground Coal Gasification (UCG) is thought to be the most favourable clean coal technology option from geological-engineering-environmental viewpoint (less polluting and high efficiency) for extracting energy from coal without digging it out or burning it on the surface. UCG process requires only injecting oxidizing agent (O2 or air with steam) as raw material, into the buried coal seam, at an effective ratio which regulates the performance of gasification. This study aims to evaluate the influence of equivalent ratio (ER) on the flow and combustion characteristics in a typical half tear-drop shape of UCG cavity which is generally formed during the UCG process. A flow modeling software, Ansys FLUENT is used to construct a 3-D model and to solve problems in the cavity. The boundary conditions are- (i) a mass-flow-inlet passing oxidizer (in this case, air) into the cavity, (ii) a fuel-inlet where the coal volatiles are originated and (iii) a pressure-outlet for flowing the product Syngas out of the cavity. A steady-state simulation has been run using k-? turbulence model. The mass flow rate of air varied according to an equivalent ratio (ER) of 0.16, 0.33, 0.49 and 0.82, while the fuel flow rate was fixed. The optimal condition of ER has been identified through observing flow and combustion characteristics, which looked apparently stable at ER 0.33. In general, the flow circulation mainly takes place around the ash-rubble pile. A high temperature zone is found at the air-releasing point of the injection pipe into the ash-rubble pile. This study could practically be useful to identify one of the vital controlling factors of gasification performance (i.e., ER impact on product gas flow characteristics) which might become a cost-effective solution in advance of commencement of any physical operation.

scholarly journals Simulation and Modeling of Flow in a Gas Compressor

2015 ◽  
Vol 2015 ◽  
pp. 1-7
Author(s):  
Anna Avramenko ◽  
Alexey Frolov ◽  
Jari Hämäläinen
Keyword(s):  
Steady State ◽  
Mass Flow ◽  
Gas Flow ◽  
Simulation Method ◽  
High Mass ◽  
Ansys Fluent ◽  
Flow Rates ◽  
Mass Flow Rates ◽  
Low Mass ◽  
Flow Through

The presented research demonstrates the results of a series of numerical simulations of gas flow through a single-stage centrifugal compressor with a vaneless diffuser. Numerical results were validated with experiments consisting of eight regimes with different mass flow rates. The steady-state and unsteady simulations were done in ANSYS FLUENT 13.0 and NUMECA FINE/TURBO 8.9.1 for one-period geometry due to periodicity of the problem. First-order discretization is insufficient due to strong dissipation effects. Results obtained with second-order discretization agree with the experiments for the steady-state case in the region of high mass flow rates. In the area of low mass flow rates, nonstationary effects significantly influence the flow leading stationary model to poor prediction. Therefore, the unsteady simulations were performed in the region of low mass flow rates. Results of calculation were compared with experimental data. The numerical simulation method in this paper can be used to predict compressor performance.

Free-Molecular Gas Flow in a Narrow (Nanosize) Channel

2014 ◽  
Vol 87 (4) ◽  
pp. 802-814
Author(s):  
V. V. Levdanskii ◽  
V. I. Roldugin ◽  
V. M. Zhdanov ◽  
V. Zdimal
Keyword(s):  
Gas Flow ◽  
Molecular Gas

scholarly journals Pressure and Gas Flow Distribution Inside the Filter of a Non-Filter Ventilated Lit Cigarette During Puffing

2017 ◽  
Vol 27 (6) ◽  
pp. 113-124
Author(s):  
Bin Li ◽  
Xiaomeng Cui ◽  
Lucan Zhao ◽  
Le Wang ◽  
Guoyong Xie ◽  
...  
Keyword(s):  
Flow Velocity ◽  
Gas Flow ◽  
Flow Direction ◽  
Flow Distribution ◽  
Mainstream Smoke ◽  
Cigarette Filter ◽  
Spatially Resolved ◽  
Dynamic Filtration ◽  
Temperature And Pressure ◽  
Burning Coal

SummaryEstablishing a realistic gas flow velocity distribution inside a cigarette filter during smoking is important to understand filtration mechanisms of different mainstream smoke species and the overall effect of filter designs on mainstream smoke composition. In this paper, an experimental method is described which directly measures the gas pressure field inside a cellulose acetate filter during cigarette smoking. This was demonstrated by using 3R4F research reference cigarettes smoked under a 35 mL puff of 6 s duration. In addition, filter temperature measurements were also carried out at multiple locations within the filter. Both the temperature and pressure sensing locations were selected to match the radial and longitudinal directions of the cigarette filter. The temperature and pressure measurements were then used to calculate the velocity according to Darcy’s Law along the mainstream flow direction in the cigarette filter at each puff. The spatially resolved maps of temperature, pressure and flow velocity on a puff-by-puff basis provide useful insights into the dynamic filtration of smoke aerosol under the influence of the approaching burning coal and progressive accumulation of smoke particulate matter.

The Theoretical and Experimental Evaluation of Gas-Particle Flow in Laser Cladding Repairing of Three Dimensions

Materials ◽  
2004 ◽  
Author(s):  
Hui-Shan Li ◽  
Xi-Chen Yang ◽  
Chun-Xian Wang
Keyword(s):  
Mass Flow Rate ◽  
Laser Cladding ◽  
Mass Flow ◽  
Flow Rate ◽  
Gas Flow ◽  
Ccd Camera ◽  
Longitudinal Axis ◽  
Three Dimensions ◽  
Theoretical Evaluation ◽  
Transportation Equipment

In this paper, the powders transportation in laser cladding repairing during the coaxial powder-feeding was evaluated. The theoretical evaluation is based on a two-fluid approach in which both the gas and particulate phase is treated each phase separately, and the only link between the phases is through the drag force in the momentum equations. The particles velocities are calculated with changes of the gas flow and mass flow rate. This is important for the coaxial nozzle and the carrier-gas powder transportation equipment characteristics determined. An experimentally of the influence of carrying gas on the powder stream was set up. The gas-particles flowing from the nozzle was illuminated by a 2D sheet of light. A typical image from the CCD camera is captured. The axial velocity and cross section were described. According to the results, it was found that: (1) Different mass flow rate Mp=0.5g/s, 0.67g/s, 0.83g/s, 1g/s, the powder stream luminance intensity and distribution will change. (2) The distribution of powder concentration at longitudinal axis from the nozzle exit is shown. The faster particulates stream has the less density per unit volume for a given mass flow rate. (3) The gas velocity for transportation is the most important parameter.

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