Numerical and Experimental Study on Soot Accumulation on the Wall of Falling Fuel Film Micro-Combustor

2010 ◽  
Author(s):  
Ning Mei ◽  
Xiaoyan Wang ◽  
Hongming Zhao ◽  
Yan Li ◽  
Hongyu Si
Keyword(s):  
Flow Field ◽  
Combustion Chamber ◽  
Turbulence Model ◽  
Complex Structure ◽  
Flow Distribution ◽  
Experimental Results ◽  
Fuel Film ◽  
Numerical Result ◽  
Different Diameters ◽  
Micro Combustor

Fluid flow contributes much to fuel-air mixture formation in a micro-combustor, the RNG k-ε turbulence model was used to simulate the cold flow field of a falling fuel film microcombustor, and comparison was made between numerical result and experimental results. It is shown that the RNG k-ε turbulence model translated the flow field of a complex structure micro-combustor and the soot accumulation on the wall of combustion chamber. The experimental results showed that soot accumulation occurs in vortex backflow area near the wall of combustion chamber and the numerical methods is helpful for understanding the way of soot accumulation in the wall of combustion chamber. Therefore, modifications on the flow field with different diameters and entrance direction of the air flow into the primary combustion chamber were made. The numerical simulation of flow distribution showed that the flow field of micro-combustor could be ideal for eliminated soot accumulation.

Numerical Simulation of Flow Field around DLR_F4 Using Meshless Method

2013 ◽  
Vol 681 ◽  
pp. 209-213
Author(s):  
Xin Jian Ma ◽  
Jun Jie Tan ◽  
Deng Feng Ren ◽  
Fang Wang
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Turbulence Model ◽  
Meshless Method ◽  
Experimental Results ◽  
Fluid Viscosity ◽  
Force Coefficient ◽  
Simulation Results ◽  
Lift And Drag ◽  
Present Simulation

In order to investigate the calculation ability of meshless method and calculation precision for lift and drag force coefficient based on N-S equations with S-A turbulence model and Euler equations, numerical simulation of flow field around the DLR-F4 wing-body, supplied by the AIAA Drag Prediction Workshop, is employed using meshless method. Furthermore, the calculated results are compared with experiment results and Waller’s simulation results achieved by MGAERO software. It’s found that the present simulation results without consideration of fluid viscosity don’t agree well with Waller’s and experimental results. The present simulation results with consideration of fluid viscosity were found to be in good agreement with experimental results. These results indicate that meshless method coupled with S-A turbulence model could predict the natural flow characteristic around the DLR-F4 wing-body configuration well.

Sensitivity Analysis of Turbulence Models for the Core Inlet Flow Distribution of PWR

2018 ◽  
Author(s):  
Lu-lu Hao ◽  
Hong Chen ◽  
Su chen Qiu
Keyword(s):  
Flow Field ◽  
Mass Flow Rate ◽  
Turbulence Model ◽  
Mass Flow ◽  
Flow Rate ◽  
Mesh Generation ◽  
Flow Distribution ◽  
Computation Model ◽  
Pressurized Water ◽  
Geometry Model

Computational Fluid Dynamics (CFD) methods have been developed into effective fluid simulation means to be used on the hydraulic design in the field of nuclear reactor. However, it is difficult to generate suitable mesh and select turbulence model for simulation because of the complex geometry structure and flow behavior in the pressure vessel. Based on CFX software, a hydraulic computation model of typical pressurized water reactor is established and the flow distribution at core inlet is analyzed. The simplified geometry model consists cold legs, downcomer, lower plenum, secondary support component, core support plate, and lower core plate. The computation model is divided into three parts for mesh generation, including the part of inlet and downcomer, the part of lower plenum and core inlet section, and the part of core. In order to reach the independence of grid several methods of mesh generation which contains different mesh density at local key parties are investigated to screen out the suitable mesh scheme. The k-ε, k-ω, and SST k-ω turbulence model are respectively used for simulation and the sensitivity of turbulence model at different locations of flow field is analyzed. The results show that the mass flow rate of the near wall flow field, computed by using k-ω turbulence model, is consistent with SST k-ω model, while the mass flow rate of central flow field computed by using k-ε turbulence agrees with SST k-ω model. The result computed by using k-ε turbulence model shows relatively uniform flow distribution at core inlet, which is more consistent with the measured data with the average difference of 3.1%. By using the k-ε model, the probability distribution of the difference between the calculated results and the experimental values follows the law of Normal distribution. The final coolant flow distribution at each orifice is evaluated, and the maximum normalized flow flux is found at center orifice while the flow rate at the edge of core is relatively lower.

Numerical Study of Classification of Ultrafine Particles in a Gas-Solid Field of Elbow-Jet Classifier

2005 ◽  
Author(s):  
Shibin Liang
Keyword(s):  
Flow Field ◽  
Ultrafine Particles ◽  
High Speed ◽  
Numerical Study ◽  
Experimental Results ◽  
Speed Flow ◽  
Fluent Software ◽  
Air Classifier ◽  
Different Diameters

Computational fluid dynamics (CFD) is applied to develop a novel submicron air classifier. Based on different inner structure sizes and positions in the elbow-jet classifier, the two-dimensional air flow field has been simulated by the Fluent software. The Coanda-effect plays a paramount role in the separation of ultrafine particles in the high-speed flow field of the elbow-jet classifier. The effects on the features of the Coanda element, i.e. a half-cylinder, have been analyzed and discussed. The trajectories of moving particles with different diameters in the channels and chambers of the classifier have been calculated under the velocity field simulation results obtained by the CFD analysis. The cut sizes of three products at the related outlets of the classifier are obtained based on the trajectories calculation of the particles and compared with the corresponding experimental results. The ground/classified experiment has been conducted by using the products outlet of a vortex jet mill as the particles feed of the elbow-jet classifier. The experimental results show that the external classifier for the vortex jet mill improves the classification of the mill significantly. The combination of the vortex jet mill with the external classifier provides a new choice of the grinding equipment for the multiple size products of fine/medium/coarse powders. A centrifugal channel has been added between the vortex jet mill and the elbow-jet classifier to improve the performance of the air classifier. Both numerical and experimental results show that the pre-distributed feed powders at the exit of the centrifugal channel have a strong effect on the fine powders separation and a less effect on the coarse powders separation.

Experimental Study of Turbulent Macroinstabilities in an Agitated System with Axial High-Speed Impeller and with Radial Baffles

1996 ◽  
Vol 61 (6) ◽  
pp. 856-867 ◽  
Author(s):  
Oldřich Brůha ◽  
Ivan Fořt ◽  
Pavel Smolka ◽  
Milan Jahoda
Keyword(s):  
Experimental Study ◽  
Flow Field ◽  
High Speed ◽  
Experimental Results ◽  
Turbulent Regime ◽  
Frequency Of Occurrence ◽  
Visualization Method ◽  
Entire Flow

The frequency of turbulent macroinstability occurrence was measured in liquids agitated in a cylindrical baffled vessel. As it has been proved by preceding experimental results of the authors, the stochastic quantity with frequency of occurrence of 10-1 to 100 s-1 is concerned. By suitable choosing the viscosity of liquids and frequency of impeller revolutins, the region of Reynolds mixing numbers was covered from the pure laminar up to fully developed turbulent regime. In addition to the equipment making it possible to record automatically the macroinstability occurrence, also the visualization method and videorecording were employed. It enabled us to describe in more detail the form of entire flow field in the agitated system and its behaviour in connection with the macroinstability occurrence. It follows from the experiments made that under turbulent regime of flow of agitated liquids the frequency of turbulent macroinstability occurrence is the same as the frequency of the primary circulation of agitated liquid.

scholarly journals Development of a two zone turbulence model and its application to the cycle-simulation

2014 ◽  
Vol 18 (1) ◽  
pp. 1-16 ◽  
Author(s):  
Momir Sjeric ◽  
Darko Kozarac ◽  
Rudolf Tomic
Keyword(s):  
High Pressure ◽  
Kinetic Energy ◽  
Flow Field ◽  
Turbulent Kinetic Energy ◽  
Turbulence Model ◽  
Combustion Process ◽  
Progress Variable ◽  
Cycle Simulation ◽  
Pressure Cycle ◽  
Turbulent Flow Field

The development of a two zone k-? turbulence model for the cycle-simulation software is presented. The in-cylinder turbulent flow field of internal combustion engines plays the most important role in the combustion process. Turbulence has a strong influence on the combustion process because the convective deformation of the flame front as well as the additional transfer of the momentum, heat and mass can occur. The development and use of numerical simulation models are prompted by the high experimental costs, lack of measurement equipment and increase in computer power. In the cycle-simulation codes, multi zone models are often used for rapid and robust evaluation of key engine parameters. The extension of the single zone turbulence model to the two zone model is presented and described. Turbulence analysis was focused only on the high pressure cycle according to the assumption of the homogeneous and isotropic turbulent flow field. Specific modifications of differential equation derivatives were made in both cases (single and two zone). Validation was performed on two engine geometries for different engine speeds and loads. Results of the cyclesimulation model for the turbulent kinetic energy and the combustion progress variable are compared with the results of 3D-CFD simulations. Very good agreement between the turbulent kinetic energy during the high pressure cycle and the combustion progress variable was obtained. The two zone k-? turbulence model showed a further progress in terms of prediction of the combustion process by using only the turbulent quantities of the unburned zone.

The Effect of Different Turbulence Models on the Emitter Discharge by Using Computational Fluid Dynamics

2013 ◽  
Vol 662 ◽  
pp. 586-590
Author(s):  
Gang Lu ◽  
Qing Song Yan ◽  
Bai Ping Lu ◽  
Shuai Xu ◽  
Kang Li
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Field ◽  
Turbulence Models ◽  
Experimental Results ◽  
Turbulent Model ◽  
Simulation Results ◽  
Rsm Model ◽  
Dynamics Method ◽  
Emitter Discharge

Four types of Super Typhoon drip emitter with trapezoidal channel were selected out for the investigation of the flow field of the channel, and the CFD (Computational Fluid Dynamics) method was applied to simulate the micro-field inside the channel. The simulation results showed that the emitter discharge of different turbulent model is 4%-14% bigger than that of the experimental results, the average discharge deviation of κ-ω and RSM model is 5, 4.5 respectively, but the solving efficiency of the κ-ω model is obviously higher than that of the RSM model.

Experimental investigation of the air flow in a simplified underhood environment

2021 ◽  
pp. 095440702110597
Author(s):  
Randi Franzke ◽  
Simone Sebben ◽  
Emil Willeson
Keyword(s):  
Flow Field ◽  
Laser Doppler Anemometry ◽  
Fluid Dynamic ◽  
Air Flow ◽  
Measurement Data ◽  
Quality Measurement ◽  
Flow Distribution ◽  
Lateral Position ◽  
Reference Case ◽  
Lateral Direction

In this paper, a simplified underhood environment is proposed to investigate the air flow distribution in a vehicle-like set-up and provide high quality measurement data that can be used for the validation of Computational Fluid Dynamic methods. The rig can be equipped with two types of front openings representative for electrified vehicles. Furthermore, it is possible to install differently shaped blockages downstream of the fan to imitate large underhood components. The distance between the blockages and the fan can be varied in longitudinal and lateral direction. The measurements are performed with Laser Doppler Anemometry at a fixed distance downstream of the fan. The results show that the lack of an upper grille opening in the configuration for a battery electric vehicle has a notable impact on the flow field in the reference case without any downstream blockage. However, the differences in the flow field between the two front designs become less when a downstream obstruction is present. The longitudinal and lateral position of the blockages have a minor impact on the flow field compared to the shape of the obstacle itself.

The Influence of Wrap Angle of Blade on the Internal Flow Field and Hydraulic Performance of Double Suction Pump

2018 ◽  
Author(s):  
Hao Chang ◽  
Weidong Shi ◽  
Wei Li ◽  
Jianrui Liu ◽  
Ling Zhou ◽  
...  
Keyword(s):  
Flow Field ◽  
Cross Section ◽  
Turbulence Model ◽  
Static Pressure ◽  
Internal Flow ◽  
Hydraulic Performance ◽  
Optimal Model ◽  
Suction Pump ◽  
External Characteristic ◽  
Wrap Angle

In order to study the influence rule of wrap angle of blade on the internal flow field and hydraulic performance of double suction pump, 5 kinds of wrap angles of blade with 100°, 110°, 120°, 130° and 140° are designed in this paper. The turbulence model and the grid type are analyzed, the performance of ES350-575 double suction pump is obtained by employ the software CFX. The static pressure and velocity distributions in the cross-section are analyzed. Therefore, the optimal model is obtained, and the relevant external characteristic test is conducted. The result shows that the reasonable increase of the wrap angle of blade can enhance the performance of the pump effectively, which can improve the static pressure and velocity distributions of the internal flow field.

scholarly journals On Application of EARSM Turbulence Model for Simulation of Flow Field behind Rack Station

2013 ◽  
Vol 45 ◽  
pp. 01013
Author(s):  
V. Běták ◽  
P. Sváček ◽  
J. Novotný ◽  
J. Fürst ◽  
J. Fořt
Keyword(s):  
Flow Field ◽  
Turbulence Model
Sign in / Sign up

Export Citation Format

Share Document