scholarly journals Effect of the location of a gas flow control element in an ejector unit on the flow pattern

2020 ◽  
Vol 2020 (3) ◽  
pp. 54-63
Author(s):  
O.D. Ihnatev ◽  
◽  
H.M. Shevelova ◽  
Keyword(s):  
Numerical Simulation ◽  
Flow Control ◽  
Flow Pattern ◽  
Flow Rate ◽  
Gas Flow ◽  
Energy Carrier ◽  
Control Element ◽  
Gas Flows ◽  
Control Parameters ◽  
Processing Technologies

This article is devoted to a numerical simulation of the flow in a jet mill ejector equipped with a gas flow control element. This element is a channel wherefrom an additional gas flow enters the accelerating tube of the ejector. The gas flows in the mill ejector are controlled using the energy of additional gas flows, thus increasing the velocity of the main flow at the outlet of the ejector accelerating tube and producing a protective layer around the tube walls to prevent their wear. At the same time, there is no substantiation for the choice of optimal control parameters, a methodology, or scientific methods for gas flow control in the ejector channels. The purpose of this work is to investigate the effect of the location of the gas flow control element on gas-dynamic ejector performance and the flow pattern in the ejector channels. A numerical study was carried out using the Ansys Fluent software package and the SST k-? turbulence model. In the course of the study, the pressure of the additional gas flow and the distance from the accelerating tube inlet to the energy carrier supply channel were varied. The angle of the additional gas flow was 20 ?. The numerical simulation gave flow patterns in the ejector as a function of the location of the gas flow control element. Streamlines of the additional gas flow were constructed. The article presents the average flow velocity at the accelerating tube outlet and the energy carrier flow rate as a function of the pressure of the additional flow of the energy carrier and the location of the gas flow control element and the maximum values of the average outlet velocity for given pressure ranges. The article substantiates the choice of the gas flow control parameters that maximize the velocity of the mixed flow at the accelerating tube outlet at a minimum gas flow rate. The results may be used in improving material processing technologies.

scholarly journals Investigation on influences of loose gas on gas-solid flows in a circulating fluidized bed (CFB) reactor using full-loop numerical simulation

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Pengju Huo ◽  
Xiaohong Li ◽  
Yang Liu ◽  
Haiying Qi
Keyword(s):  
Numerical Simulation ◽  
Flow Rate ◽  
Gas Flow ◽  
Circulating Fluidized Bed ◽  
Separation Efficiency ◽  
Circulation Rate ◽  
Solid Mass ◽  
Gas Flow Rate ◽  
Gas Leakage ◽  
Mass Circulation

AbstractThe influences of loose gas on gas-solid flows in a large-scale circulating fluidized bed (CFB) gasification reactor were investigated using full-loop numerical simulation. The two-fluid model was coupled with the QC-energy minimization in multi-scale theory (EMMS) gas-solid drag model to simulate the fluidization in the CFB reactor. Effects of the loose gas flow rate, Q, on the solid mass circulation rate and the cyclone separation efficiency were analyzed. The study found different effects depending on Q: First, the particles in the loop seal and the standpipe tended to become more densely packed with decreasing loose gas flow rate, leading to the reduction in the overall circulation rate. The minimum Q that can affect the solid mass circulation rate is about 2.5% of the fluidized gas flow rate. Second, the sealing gas capability of the particles is enhanced as the loose gas flow rate decreases, which reduces the gas leakage into the cyclones and improves their separation efficiency. The best loose gas flow rates are equal to 2.5% of the fluidized gas flow rate at the various supply positions. In addition, the cyclone separation efficiency is correlated with the gas leakage to predict the separation efficiency during industrial operation.

Experimental, Numerical, and Statistical Investigation of Two Phase Flow in a Cylindrical Perforation Tunnel

2021 ◽  
Author(s):  
Ekhwaiter Abobaker ◽  
Abadelhalim Elsanoose ◽  
Mohammad Azizur Rahman ◽  
Faisal Khan ◽  
Amer Aborig ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Steady State ◽  
Statistical Analysis ◽  
Flow Rate ◽  
Gas Flow ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Gas Flow Rate ◽  
Two Phase ◽  
Flow Through

Abstract Perforation is the final stage in well completion that helps to connect reservoir formations to wellbores during hydrocarbon production. The drilling perforation technique maximizes the reservoir productivity index by minimizing damage. This can be best accomplished by attaining a better understanding of fluid flows that occur in the near-wellbore region during oil and gas operations. The present work aims to enhance oil recovery by modelling a two-phase flow through the near-wellbore region, thereby expanding industry knowledge about well performance. An experimental procedure was conducted to investigate the behavior of two-phase flow through a cylindrical perforation tunnel. Statistical analysis was coupled with numerical simulation to expand the investigation of fluid flow in the near-wellbore region that cannot be obtained experimentally. The statistical analysis investigated the effect of several parameters, including the liquid and gas flow rate, liquid viscosity, permeability, and porosity, on the injection build-up pressure and the time needed to reach a steady-state flow condition. Design-Expert® Design of Experiments (DoE) software was used to determine the numerical simulation runs using the ANOVA analysis with a Box-Behnken Design (BBD) model and ANSYS-FLUENT was used to analyses the numerical simulation of the porous media tunnel by applying the volume of fluid method (VOF). The experimental data were validated to the numerical results, and the comparison of results was in good agreement. The numerical and statistical analysis demonstrated each investigated parameter’s effect. The permeability, flow rate, and viscosity of the liquid significantly affect the injection pressure build-up profile, and porosity and gas flow rate substantially affect the time required to attain steady-state conditions. In addition, two correlations obtained from the statistical analysis can be used to predict the injection build-up pressure and the required time to reach steady state for different scenarios. This work will contribute to the clarification and understanding of the behavior of multiphase flow in the near-wellbore region.

Numerical Simulation and Experimental Study on Tar Decomposition of Low-Pressure Ejection Type Burner

2015 ◽  
Vol 1092-1093 ◽  
pp. 200-206
Author(s):  
De Fan Qing ◽  
Mao Kui Zhu ◽  
Yang Cheng Luo ◽  
Ya Long Zhang ◽  
Ai Rui Chen ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Flow Rate ◽  
Gas Flow ◽  
Low Pressure ◽  
Orthogonal Test ◽  
Nozzle Diameter ◽  
Design Parameters ◽  
Minor Effect ◽  
Gas Flow Rate ◽  
Tar Cracking

The tar decomposition of low-pressure ejection type burner was researched. The burner used software to simulate and analyse impact of the nozzle diameter d, the gas flow rate V and the distance of the nozzle to the wall L on tar cracking. The orthogonal test were used for design parameters d, V and L, the optimization values of these three parameters were carried out, and experimental method was used for test the numerical simulation results. Numerical simulation and experimental results showed that the greatest impact on tar cracking is the nozzle diameter d, the minor effect is the distance of the nozzle to the wall L and the weakest effect is the gas flow rate V, and when the nozzle diameter d=4 mm, the distance L=18 mm and the gas flow rate V=0.10 m3/h, the tar cracking is the most efficiency.

Numerical Simulation of Gas Flow Pattern in Cyclone Spray Scrubber

2011 ◽  
Vol 233-235 ◽  
pp. 701-706
Author(s):  
Bing Tao Zhao ◽  
Yi Xin Zhang ◽  
Kai Bin Xiong
Keyword(s):  
Numerical Simulation ◽  
Fluid Flow ◽  
Flow Pattern ◽  
Gas Flow ◽  
Stokes Equations ◽  
Tangential Velocity ◽  
Navier Stokes ◽  
Computational Domain ◽  
Spray Scrubber ◽  
Cfd Method

The numerical simulation of the fluid flow is presented by CFD technique to characterize the flow pattern of cyclone spray scrubber. In this process, the Reynolds-averaged Navier-Stokes equations with the Reynolds stress turbulence model (RSM) for fluid flow are solved by use of the finite volume method based on the SIMPLE pressure correction algorithm in the fluid computational domain. According to the computational results, the tangential velocity, axial velocity and turbulence intensity of the gas flow are addressed in the different flowrate. The results indicate that the CFD method can effectively reveal the mechanism of gas flow in the cyclone spray scrubber.

scholarly journals Numerical simulation of turbulent duct flows with constant power input

2014 ◽  
Vol 750 ◽  
pp. 191-209 ◽  
Author(s):  
Yosuke Hasegawa ◽  
Maurizio Quadrio ◽  
Bettina Frohnapfel
Keyword(s):  
Numerical Simulation ◽  
Reynolds Number ◽  
Flow Control ◽  
Flow Rate ◽  
Power Input ◽  
Viscous Drag ◽  
Duct Flow ◽  
Constant Power ◽  
Additional Advantage ◽  
Standard Case

AbstractThe numerical simulation of a flow through a duct requires an externally specified forcing that makes the fluid flow against viscous friction. To this end, it is customary to enforce a constant value for either the flow rate (CFR) or the pressure gradient (CPG). When comparing a laminar duct flow before and after a geometrical modification that induces a change of the viscous drag, both approaches lead to a change of the power input across the comparison. Similarly, when carrying out direct numerical simulation or large-eddy simulation of unsteady turbulent flows, the power input is not constant over time. Carrying out a simulation at constant power input (CPI) is thus a further physically sound option, that becomes particularly appealing in the context of flow control, where a comparison between control-on and control-off conditions has to be made. We describe how to carry out a CPI simulation, and start with defining a new power-related Reynolds number, whose velocity scale is the bulk flow that can be attained with a given pumping power in the laminar regime. Under the CPI condition, we derive a relation that is equivalent to the Fukagata–Iwamoto–Kasagi relation valid for CFR (and to its extension valid for CPG), that presents the additional advantage of naturally including the required control power. The implementation of the CPI approach is then exemplified in the standard case of a plane turbulent channel flow, and then further applied to a flow control case, where a spanwise-oscillating wall is used for skin-friction drag reduction. For this low-Reynolds-number flow, using 90 % of the available power for the pumping system and the remaining 10 % for the control system is found to be the optimum share that yields the largest increase of the flow rate above the reference case where 100 % of the power goes to the pump.

scholarly journals Calculation of a 3D turbulent flow in aircraft gas turbine engine ducts

2020 ◽  
Vol 2020 (4) ◽  
pp. 65-71
Author(s):  
Yu.A. Kvasha ◽  
Keyword(s):  
Numerical Simulation ◽  
Turbulent Flow ◽  
Gas Turbine ◽  
Gas Flow ◽  
Turbine Engines ◽  
Gas Flows ◽  
Gas Turbine Engines ◽  
Compressor Inlet ◽  
Air Intake ◽  
Engine Compressor

This work is devoted to the development of approaches to the numerical simulation of 3D turbulent gas flows in different ducts of aircraft gas turbine engines, in particular in inlet device ducts. Inlet devices must provide large values of the total pressure recovery factor and flow uniformity at the engine compressor inlet. The aim of this work is the verification of the operability of a technique developed earlier for the calculation of the parameters of a 3D turbulent flow in complex-shape ducts. The basic approach is a numerical simulation of 3D turbulent gas flows on the basis of the complete averaged Navier¬–Stokes equations and a two-parameter turbulence model. The proposed technique of numerical simulation of a 3D gas flow was tested by calculating a 3D laminar flow in a square pipe bent at a right angle. The calculated flow pattern is in satisfactory agreement with the experimental data on the flow structure in a pipe elbow reported in the literature. Based on a numerical simulation of a 3D turbulent flow in the air duct of one of the air intake configurations for an aircraft turboprop engine, the efficiency of that configuration is assessed. The calculated flow parameter nonuniformity at the air intake outlet, i. e., at the compressor inlet, is compared with that obtained earlier for another air intake configuration for the same engine. It is pointed out that the air intake configuration considered earlier provides a much more uniform flow parameter distribution at the engine compressor inlet. On the whole, this work shows that the quality of subsonic air intakes for aircraft gas turbine engines can be assessed using the proposed numerical technique of 3D gas flow simulation. The results obtained may be used in the aerodynamic improvement of inlet devices for aircraft engines of different types.

scholarly journals Particle deposition characteristics in entrained flow coal gasifier

2012 ◽  
Vol 16 (5) ◽  
pp. 1544-1548
Author(s):  
Sheng Liu ◽  
Ying-Li Hao
Keyword(s):  
Numerical Simulation ◽  
Flow Rate ◽  
Particle Deposition ◽  
Gas Flow ◽  
Water Flow Rate ◽  
Deposition Process ◽  
The Other ◽  
Central Channel ◽  
Gas Flow Rate ◽  
Coal Gasifier

Cold state experiment and numerical simulation are carried out to study particle deposition process. The deposit mass can be divided into two parts, one directly collides with the wall and the other is brought by the backflow. The deposit flux increases with the increase of gas flow rate or water flow rate or both, and decreases with the increase of the central channel gas flow rate.

A CFD Analysis for the Advanced Accumulator

2014 ◽  
Author(s):  
Donghua Lu ◽  
Kuo Wang ◽  
Qianhua Su ◽  
Jun Xing
Keyword(s):  
Fluid Dynamics ◽  
Flow Control ◽  
Flow Pattern ◽  
Flow Rate ◽  
Vortex Chamber ◽  
Flow Chamber ◽  
High Flow ◽  
Low Flow ◽  
Cfd Analysis ◽  
Computational Fluid Dynamics Cfd

A new design for the flow control component of an advanced accumulator (ACC) was introduced and numerically investigated in the paper. The flow control component can produce high flow rate and low flow rate at the different stages during the safety injection. The FLUENT computational fluid dynamics (CFD) was used in the simulation of the flow pattern in the flow chamber and the outlet. The flow pattern and pressure gradient in the vortex chamber were investigated. The results show the design can realize the high flow and low flow in this design.

Numerical Simulation on the Parallel Combined Nozzles of Mini/Micro Gas Flow Standard Device

2012 ◽  
Vol 472-475 ◽  
pp. 2000-2003
Author(s):  
Jin Long Meng ◽  
Zhao Qin Yin
Keyword(s):  
Fluid Dynamics ◽  
Numerical Simulation ◽  
Flow Rate ◽  
Gas Flow ◽  
Flow Characteristics ◽  
Micro Gas Flow ◽  
Actual Flow Rate ◽  
Actual Flow ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method

The flow characteristics in mini/micro sonic nozzles have been studied in this paper using the computational fluid dynamics (CFD) method. The result shows that the flow rate of the parallel combined nozzles is not equal to but smaller than that of the sum of the nozzles. The reason is the each effect of the air after nozzles, which changes the flow field parameters .The more number of the parallel combined nozzles, the bigger error exits between actual flow rate and that of the sum of the nozzles. The result is consistent to the experiment. The study also shows the smaller of the nozzle’s diameter, the bigger error exits.

scholarly journals MODELING OF GAS-DYNAMIC PROCESSES IN THE ELEMENTS OF IMPULSE EJECTOR

2021 ◽  
pp. 66-72
Author(s):  
G. O. Voropaiev ◽  
Ia. V. Zagumennyi ◽  
N. V. Rozumnyuk
Keyword(s):  
Numerical Simulation ◽  
High Pressure ◽  
Flow Rate ◽  
Gas Flow ◽  
Dynamic Processes ◽  
Stable Operation ◽  
Operating Pressure ◽  
Gas Generator ◽  
Gas Dynamic ◽  
Ejector Nozzle

The paper presents the numerical results on gas-dynamic processes in various elements of the impulse ejector, including pre-chamber, supersonic nozzle and mixing chamber, to determine optimal geometric parameters providing the given flow rate characteristics. At an extra-high pressure of the ejecting gas (>100 bar) it is impossible to create a nozzle design with continuously changing cross-sectional area and limited nozzle length. So, it is necessary to place a pre-chamber between the gas generator and the ejector nozzle for throttling full gas pressure. In order to optimize the pre-chamber parameters in the ejector with discrete holes of the gas generator and the operating pressure in the range of 400÷1000 bar, a series of calculations were performed to determine the pre-chamber parameters, ensuring stable operation of the supersonic annular nozzle at the high pressure of 35÷45 bar and the flow rate of 0.5÷0.6 kg/s. 3D numerical simulation of the gas flow into the pre-chamber through the gas generator holes shows the degree of the flow pattern non-uniformity in the pre-chamber at the ejector nozzle inlet is quite low. This justifies the numerical simulation of gas flow in the ejector in axisymmetric formulation and allows restricting the number of the gas generator holes without inducing significant non-uniformity in the azimuthal direction.

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