Assessing the flow characteristics of self-compacting concrete via numerical simulations of flow tests

2018 ◽  
pp. 173-182
Author(s):  
S. Kulasegaram ◽  
B.L. Karihaloo
Keyword(s):  
Numerical Simulations ◽  
Flow Characteristics ◽  
Self Compacting Concrete

scholarly journals Analytical and Numerical Feasibility Analysis of a Contra-Rotary Ramjet Engine

Energies ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 163
Author(s):  
Tomasz Laube ◽  
Janusz Piechna
Keyword(s):  
Numerical Simulations ◽  
Stokes Equations ◽  
Analytical Data ◽  
Combustion Process ◽  
Flow Characteristics ◽  
Combustion Model ◽  
Similar Data ◽  
High Rotational Speed ◽  
Jet Engine ◽  
Ramjet Engine

A new idea for a contra-rotary ramjet engine is presented. To define the theoretical limits of the non-typical, contra-rotary ramjet engine configuration, its analytical model was developed. The results obtained from that model and the analytical results were compared with those received from numerical simulations. The main weakness of existing rotary ramjet engine projects is the very high rotational speed of the rotor required for achieving supersonic inlet flow. In this paper, a new idea for a contra-rotary ramjet engine (CORRE) is presented and analyzed. This paper presents the results of analytical analysis and numerical simulations of a jet engine system with two rotors rotating in opposite directions. Contra-rotating rotors generate a supersonic air velocity at the inlet to the compressor at two times slower rotor’s speed. To determine the flow characteristics, combustion process, and engine efficiency of the double-rotor engine, a numerical solution of the average Navier-Stokes equations was used with the k-eps turbulence model and the non-premixed combustion model. The results of numerical simulations of flow and the combustion process inside the contra-rotary jet engine achieving a shockwave compression are shown and compared with similar data for a single-rotor engine design and analytical data. This paper presents only the calculation results of the flow processes and the combustion process, indicating the advantages of the proposed double-rotor design. The results of the numerical analysis were presented on the contours and diagrams of the pressure and flow velocity, temperature distribution, and mass fraction of the fuel.

scholarly journals Study the effect of angle of attack on flow characteristics at racing bike helmet using CFD

2018 ◽  
Vol 204 ◽  
pp. 06001
Author(s):  
Syamsuri ◽  
M Hasan Syafik ◽  
Yudho Putro Iswanto
Keyword(s):  
Numerical Simulations ◽  
Drag Coefficient ◽  
Aerodynamic Force ◽  
Angle Of Attack ◽  
Flow Characteristics ◽  
Reynold Number ◽  
Attack Angle ◽  
Large Area ◽  
Drag Racing ◽  
Simulation Results

At a cyclist drag racing champions greatly affect the speed of the bike, especially on the use of racing bike helmets. If the aerodynamic force from the racing bike helmet is getting smaller than the use of helmets on the bike racing will be more optimal and will affect the rate of the racer. In this study, numerical simulations were used to investigate the magnitude of the drag force that occurs around the surface of the helmet. With CFD software, 4 variations of attack angle 0°, 10°, 20° and 30° and variations of Reynold number 7.14x104, 1.00x105, and 1.16x105 are simulated to determine the flow characteristics of each state. The simulation results show that large area vortex is formed at the bottom of the helmet curve and dominates at the attack angle 30°. The result of the drag coefficient generated at the angle of attack 0° to 20° tends to decrease but at the attack angle 200 and 30° the drag coefficient increases.

Flow Characteristics of Rarified Gases in Micro-Grooved Channels by the Lattice-Boltzmann Method

2008 ◽  
Author(s):  
Amador M. Guzma´n ◽  
Andre´s J. Di´az ◽  
Luis E. Sanhueza ◽  
Rodrigo A. Escobar
Keyword(s):  
Numerical Simulations ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Pressure Ratio ◽  
Plane Channel ◽  
Flow Characteristics ◽  
Numerical Results ◽  
Knudsen Numbers ◽  
Channel Configuration ◽  
Boltzmann Method

The flow characteristics of a rarified gas have been investigated in microgrooved channels. The governing Boltzmann Transport Equation (BTE) is solved by the Lattice-Boltzmann method (LBM) for the Knudsen number range of 0.01–0.1. First, the compressibility and rarified effects are investigated in a plane channel by performing numerical simulations for different Knudsen numbers, pressure ratio and accommodation coefficients with the objective of validating the computational code used in this investigation and determining the transition characteristics from the macro to microscale. The numerical predictions are compared to existing analytical and numerical results. Then, numerical simulations are performed for microgrooved channels for the Knudsen numbers range of [0.01–0.1]. Different meshes are used for preserving numerical stabilities and obtaining accurate enough numerical results. For the microgrooved channel configuration, the fluid characteristics are determined in terms of pressure ratio and Knudsen numbers. The numerical results are compared to existing analytical predictions and numerical results obtained from plane channel and one cavity simulations.

Flow Field Numerical Simulation on a Continuous Powder Surface Modifying Machine for Non-Metallic Material

2012 ◽  
Vol 246-247 ◽  
pp. 355-359
Author(s):  
Cui Ping Wu ◽  
Shui Lin Zheng ◽  
Jian Jun Luo
Keyword(s):  
Flow Field ◽  
Numerical Simulations ◽  
Two Phase Flow ◽  
Concentration Field ◽  
Flow Characteristics ◽  
Phase Flow ◽  
Mechanism Study ◽  
Two Phase ◽  
Metallic Material ◽  
Powder Surface

In order to study the two-phase flow field in the SLG continuous powder surface modifying machine for non-metallic material, which have been widely used in the powder engineering of China, a three-dimensional CFD model is developed to make the numerical simulations of the inner gas-particle flow field based on the industrial SLG-3/600 type modifying machine. By the help of the Fluent software, the gas velocity field, pressure field, particle concentration field and moving trace of the two-phase flow field are obtained. The simulation results indicate that these fields are distributed non-uniformly in the SLG modifying machine. Besides, a shortcut phenomenon is observed during the moving of the particles. The numerical simulations can not only depict the flow characteristics inside the SLG modifying machine, but also present useful reference to the mechanism study and optimal design to further improve its structure and working parameters in the future.

A Prediction of the Optimal Blank Contour of an Inner Elliptic Flange from Flanging

2012 ◽  
Vol 152-154 ◽  
pp. 931-934
Author(s):  
Chin Tarn Kwan ◽  
Jui Tsai Chang
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Numerical Simulations ◽  
Process Parameters ◽  
Material Flow ◽  
Flow Characteristics ◽  
Data Sets ◽  
The Finite Element Method ◽  
Aspect Ratios ◽  
Abductive Network

In this paper, the finite element method is employed in conjunction with the abductive network to predict the optimum blank contour of an inner elliptic flange with unevenness in the flanging process. Different flange heights combined with various aspect ratios of the inner elliptic flange are taken into account as the process parameters in this study. A finite element-based code is utilized to investigate the material flow characteristics under different process parameters, and the abductive network is then employed to synthesize the data sets obtained from numerical simulations, thus establishing a predictive model. From this model, an optimal blank contour for producing an elliptic inner flange with unevenness can be found.

Application of Abductive Network and FEM to Predict the Optimal Blank Contour of an Inner Elliptic Flange from Flanging

2012 ◽  
Vol 445 ◽  
pp. 253-258
Author(s):  
Chin Tarn Kwan ◽  
Jui Tsai Chang ◽  
Ching Tien Lin
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Numerical Simulations ◽  
Process Parameters ◽  
Material Flow ◽  
Flow Characteristics ◽  
Data Sets ◽  
The Finite Element Method ◽  
Aspect Ratios ◽  
Abductive Network

In this paper, the finite element method is employed in conjunction with the abductive network to predict the optimum blank contour of an inner elliptic flange with unevenness in the flanging process. Different flange heights combined with various aspect ratios of the inner elliptic flange are taken into account as the process parameters in this study. A finite element-based code is utilized to investigate the material flow characteristics under different process parameters, and the abductive network is then employed to synthesize the data sets obtained from numerical simulations, thus establishing a predictive model. From this model, an optimal blank contour for producing an elliptic inner flange with unevenness can be found.

scholarly journals The Influence of the Nature of Different Sands on the Rheological and Mechanical Behavior of Self-compacting Concretes

2020 ◽  
Author(s):  
Baali Laid ◽  
Larbi B Belagraa ◽  
Zeghichi Leila ◽  
Benhamouda Abdelhakim
Keyword(s):  
Research Work ◽  
Flow Characteristics ◽  
Point Of View ◽  
Cement Matrix ◽  
Mechanical Resistance ◽  
Self Compacting Concrete ◽  
Simple Effect ◽  
Fresh State ◽  
Mechanical Strengths ◽  
Local Materials

Self-compacting concretes represent a new advance for concrete construction because they offer many advantages from the economic, technical and social point of view. They are very fluid concretes, which are put in place without vibration. When pouring into a formwork, tightening a BAP is ensured by the simple effect of gravity. Thanks to their formulation, they offer exceptional flow characteristics and filling formwork while resisting perfectly segregation. Homogeneous and stable, they have resistances and durability similar to those of traditional concretes of which they are differentiated by their properties in the fresh state. The use of self-compacting concrete reduces the noise nuisance, as well as the hardness of the work. This research work is part of a policy of contributing to the improvement of the properties of self-compacting concretes prepared from local materials in the M’sila region. In this study, we are interested in obtaining the most suitable concrete formulation for the different local materials of the M’sila region. Our study is directed towards the effect of the following parameters on the physico-mechanical properties of the composite such as: dynamic segregation, spreading diameter as well as mechanical strengths (compression, traction). It is therefore a question of determining the criteria to be imposed on these parameters, in order to lead to the construction of a self-compacting concrete characterized by  an acceptable resistance. The experimental results of compressive strengths show significant behaviors between BAP and BV. They allowed to distinguish a resistance gain between 15.11 and 49.28, this gain is explained by a rehydration of the cement matrix due to the migration of the water through the pores for the BAP, but also to better binding properties of the hydrates forms. Keywords: SCC, Rheological behavior, Mechanical resistance, Binder

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