A numerical study on combined baffles quick-separation device

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Ehsan Dehdarinejad ◽  
Morteza Bayareh ◽  
Mahmud Ashrafizaadeh
Keyword(s):  
Turbulent Flows ◽  
Separation Efficiency ◽  
Numerical Study ◽  
Turbulence Models ◽  
Complete Separation ◽  
Solid Particles ◽  
Flow Rates ◽  
Separation Device ◽  
Coupling Technique ◽  
Laminar And Turbulent Flows

Abstract The transfer of particles in laminar and turbulent flows has many applications in combustion systems, biological, environmental, nanotechnology. In the present study, a Combined Baffles Quick-Separation Device (CBQSD) is simulated numerically using the Eulerian-Lagrangian method and different turbulence models of RNG k-ε, k-ω, and RSM for 1–140 μm particles. A two-way coupling technique is employed to solve the particles’ flow. The effect of inlet flow velocity, the diameter of the splitter plane, and solid particles’ flow rate on the separation efficiency of the device is examined. The results demonstrate that the RSM turbulence model provides more appropriate results compared to RNG k-ε and k-ω models. Four thousand two hundred particles with the size distribution of 1–140 µm enter the device and 3820 particles are trapped and 380 particles leave the device. The efficiency for particles with a diameter greater than 28 µm is 100%. The complete separation of 22–28 μm particles occurs for flow rates of 10–23.5 g/s, respectively. The results reveal that the separation efficiency increases by increasing the inlet velocity, the device diameter, and the diameter of the particles.

Numerical Assessment of Different Turbulence Models for Slot Jet Impinging on Flat and Concave Surfaces

2002 ◽  
Author(s):  
Rongguang Jia ◽  
Masoud Rokni ◽  
Bengt Sunde´n
Keyword(s):  
Turbulent Flows ◽  
Numerical Study ◽  
Turbulence Models ◽  
Detailed Comparison ◽  
Reynolds Numbers ◽  
Reynolds Stress Model ◽  
Eddy Viscosity Model ◽  
Flow And Heat Transfer ◽  
Numerical Assessment ◽  
Transfer Problems

A numerical study has been carried out for slot jet impinging on flat and concave surfaces. Five turbulence models are employed for the predictions of these strongly strained turbulent flows, namely linear eddy viscosity model (LEVM), low-Re explicit algebraic Reynolds stress model (EASM) and three different V2F models. A bounded formulation for Cμ was also introduced to account for the better prediction of the wall jet development. The studied Reynolds numbers vary from 8,000 to 20,000, and nozzle-to-surface distance (H) is in the range of 1≤H/B≤8. Detailed comparison is made between the results from the models and available experimental data to test the ability of the models in predicting these fluid flow and heat transfer problems.

scholarly journals Calculation of the Incompressible Viscous Fluid Flow in Piston Seals of Piston Hybrid Power Machines

Machines ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 21
Author(s):  
Viktor Shcherba ◽  
Viktor Shalai ◽  
Nikolay Pustovoy ◽  
Evgeniy Pavlyuchenko ◽  
Sergey Gribanov ◽  
...  
Keyword(s):  
Turbulent Flows ◽  
Experimental Studies ◽  
Turbulence Models ◽  
Initial Boundary ◽  
Flow Models ◽  
Hybrid Power ◽  
Different Types ◽  
Physical Laws ◽  
Step Type ◽  
Laminar And Turbulent Flows

The article considers the calculation of the flow of a viscous incompressible fluid in piston seals of piston hybrid power machines. The most widely used and effective seals are considered: a smooth gap seal and a step-type gap seal, and—based on the references analyses—the initial boundary conditions for their calculation are determined. The laminar and turbulent flows in gap seals are calculated based on the well-known analytical relationships, experimental studies and flow models, including the k-ε, Menter’s Shear StressTransport (SST) and Reynolds Stress (RSM) turbulence models. The effectiveness of using each model to determine average velocities, flow rates, and velocity plots in the cross section of a gap seal, as well as the adequacy of the description of known physical laws, is estimated. The results proved that the RSM turbulence model is better for the gap seals of different types under different modes of motion.

Simple Particle Separator for the Secondary Air System of Gas Turbines

2012 ◽  
Author(s):  
Natalia García Víllora ◽  
Klaus Dullenkopf ◽  
Hans-Jörg Bauer ◽  
Cyrille Bricaud ◽  
Thomas Zierer
Keyword(s):  
Turbulent Flows ◽  
Gas Turbines ◽  
Separation Efficiency ◽  
Cooling System ◽  
Material Selection ◽  
Solid Particles ◽  
Air System ◽  
Secondary Air ◽  
Institute Of Technology ◽  
Particle Separator

In heavy-duty gas turbines as well as in aero-engines, air is extracted from the compressor and led to the hot parts of the combustor and the turbine in order to cool them. Despite active design solutions such as material selection, and inclusion of compressor inlet filters, dust holes, and so on, the cooling air can be charged with solid particles, which can block the cooling holes. Therefore prediction of the particle behaviour within the secondary air system remains crucial for the design of a robust and efficient cooling system for the hot parts. For this study a particle separator prototype was designed by Alstom and its particle separation efficiency together with its total pressure losses were measured at the Institute of Thermal Turbomachinery (ITS) at the Karlsruher Institute of Technology (KIT) for two geometrical configurations and numerous flow conditions. The test rig design was optimized to provide accurate boundary conditions for the simulations. In addition, the influence of the particle shape, size, and density on the separation efficiency was studied. The experimental results were used to validate the predicted flow field and to evaluate standard methods available in a commercial CFD-solver, to simulate the interaction of solid particles with turbulent flows and the containing walls. Comparisons between the measured and calculated separation efficiencies were performed for spherical and flat particles with different Stokes numbers. In particular, the way in which a simple modelling approach used for the prediction of sphere trajectories can be transferred to flat particles was investigated. Finally this study delivers generic data for improved modelling of solid particles, like spheres and flat particles, in turbulent flows.

A Numerical Study of Laminar and Turbulent Heat Transfer in a Periodically Corrugated Wall Channel

1985 ◽  
Vol 107 (3) ◽  
pp. 564-569 ◽  
Author(s):  
R. S. Amano
Keyword(s):  
Heat Transfer ◽  
Turbulent Flows ◽  
Solution Method ◽  
Numerical Study ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Complex Flow ◽  
Flow Phenomena ◽  
Corrugated Wall ◽  
Laminar And Turbulent Flows

A numerical study is reported on hydrodynamic and heat transfer characteristics in a periodically corrugated wall channel for both laminar and turbulent flows. For turbulent flows the k-ε turbulence model with a refined near-wall model is adopted for the computation of the flow field for step ratios H/W ranging from two to four. The Reynolds number considered in this study varies from 10 to 25,000. The solution method of the governing transport equations is based on the modified hybrid scheme. As a result of extensive computations, the complex flow patterns in the perpendicularly corrugated wall channel are clarified and the mechanisms of heat transfer are explained relating to the flow phenomena of separation, deflection, recirculation, and reattachment. Finally it was observed that the effect of the step ratio on the local Nusselt number is minor. Moreover, it was found that both skin friction and heat transfer patterns change drastically from laminar to turbulent flows.

scholarly journals Numerical Study toward Optimization of Spray Drying in a Novel Radial Multizone Dryer

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1233
Author(s):  
Umair Jamil Ur Rahman ◽  
Artur Krzysztof Pozarlik ◽  
Thomas Tourneur ◽  
Axel de Broqueville ◽  
Juray De Wilde ◽  
...  
Keyword(s):  
Spray Drying ◽  
Droplet Size ◽  
Separation Efficiency ◽  
Numerical Study ◽  
Three Dimensional ◽  
Droplet Size Distribution ◽  
Vortex Chamber ◽  
Temperature Pattern ◽  
Multiphase Model ◽  
Drying Technology

In this paper, an intensified spray-drying process in a novel Radial Multizone Dryer (RMD) is analyzed by means of CFD. A three-dimensional Eulerian–Lagrangian multiphase model is applied to investigate the effect of solids outlet location, relative hot/cold airflow ratio, and droplet size on heat and mass transfer characteristics, G-acceleration, residence time, and separation efficiency of the product. The results indicate that the temperature pattern in the dryer is dependent on the solids outlet location. A stable, symmetric spray behavior with maximum evaporation in the hot zone is observed when the solids outlet is placed at the periphery of the vortex chamber. The maximum product separation efficiency (85 wt %) is obtained by applying high G-acceleration (at relative hot/cold ratio of 0.75) and narrow droplet size distribution (45–70 µm). The separation of different sized particles with distinct drying times is also observed. Smaller particles (<32 µm) leave the reactor via the gas outlet, while the majority of big particles leave it via the solids outlet, thus depicting in situ particle separation. The results revealed the feasibility and benefits of a multizone drying operation and that the RMD can be an attractive solution for spray drying technology.

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