Experimental and Computational Analyses of Methane and Hydrogen Mixing in a Model Premixer

2011 ◽  
Vol 133 (10) ◽  
Author(s):  
Amin Akbari ◽  
Scott Hill ◽  
Vincent McDonell ◽  
Scott Samuelsen
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Schmidt Number ◽  
Fuel Injection ◽  
Agricultural Waste ◽  
Flux Ratio ◽  
Systematic Evaluation ◽  
Efficient Design ◽  
Efficient Manner ◽  
Turbulent Schmidt Number

The mixing of fuel and air in combustion systems plays a key role in overall operability and emissions performance. Such systems are also being looked to for operation on a wide array of potential fuel types, including those derived from renewable sources such as biomass or agricultural waste. The optimization of premixers for such systems is greatly enhanced if efficient design tools can be utilized. The increased capability of computational systems has allowed tools such as computational fluid dynamics to be regularly used for such purpose. However, to be applied with confidence, validation is required. In the present work, a systematic evaluation of fuel mixing in a specific geometry, which entails cross flow fuel injection into axial nonswirling air streams has been carried out for methane and hydrogen. Fuel concentration is measured at different planes downstream of the point of injection. In parallel, different computational fluid dynamics approaches are used to predict the concentration fields resulting from the mixing of fuel and air. Different steady turbulence models including variants of Reynolds averaged Navier–Stokes (RANS) have been applied. In addition, unsteady RANS and large eddy simulation are used. To accomplish mass transport with any of the RANS approaches, the concept of the turbulent Schmidt number is generally used. As a result, the sensitivity of the RANS simulations to different turbulent Schmidt number values is also examined. In general, the results show that the Reynolds stress model, with use of an appropriate turbulent Schmidt number for the fuel used, provides the best agreement with the measured values of the variation in fuel distribution over a given plane in a relatively time efficient manner. It is also found that, for a fixed momentum flux ratio, both hydrogen and methane penetrate and disperse in a similar manner for the flow field studied despite their significant differences in density and diffusivity.

Experimental and Computational Analyses of Methane and Hydrogen Mixing in a Model Premixer

2010 ◽  
Author(s):  
Amin Akbari ◽  
Scott Hill ◽  
Vincent McDonell ◽  
Scott Samuelsen
Keyword(s):  
Schmidt Number ◽  
Fuel Injection ◽  
Agricultural Waste ◽  
Cross Flow ◽  
Flux Ratio ◽  
Turbulence Models ◽  
Systematic Evaluation ◽  
Efficient Design ◽  
Efficient Manner ◽  
Turbulent Schmidt Number

The mixing of fuel and air in combustion systems plays a key role in overall operability and emissions performance. Such systems are also being looked to for operation on a wide array of potential fuel types, including those derived from renewable sources such as biomass or agricultural waste. The optimization of premixers for such systems is greatly enhanced if efficient design tools can be utilized. The increased capability of computational systems has allowed tools such as computational fluid dynamics to be regularly used for such purpose. However, to be applied with confidence, validation is required. In the present work, a systematic evaluation of fuel mixing in a specific geometry which entails cross flow fuel injection into axial non-swirling air streams has been carried out for methane and hydrogen. Fuel concentration is measured at different planes downstream of the point of injection. In parallel, different CFD approaches are used to predict the concentration fields resulting from the mixing of fuel and air. Different steady turbulence models including variants of Reynolds Averaged Navier Stokes (RANS) have been applied. In addition, unsteady RANS and Large Eddy Simulation (LES) are used. To accomplish mass transport with any of the RANS approaches, the concept of the turbulent Schmidt number is generally used. As a result, the sensitivity of the RANS simulations to different turbulent Schmidt number values is also examined. In general, the results show that the Reynolds Stress Model, with use of an appropriate turbulent Schmidt number for the fuel used, provides the best agreement with the measured values of the variation in fuel distribution over a given plane in a relatively time efficient manner. It is also found that, for a fixed momentum flux ratio, both hydrogen and methane penetrate and disperse in a similar manner for the flowfield studied despite their significant differences in density and diffusivity.

Analysis for the Effect of Wind Barrier on Reducing Wind Velocity across a Bridge

2012 ◽  
Vol 256-259 ◽  
pp. 2739-2742
Author(s):  
Ji Hong Bi ◽  
Peng Lu ◽  
Jian Wang ◽  
Chun Bao
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Speed ◽  
Wind Velocity ◽  
Efficient Design ◽  
Wind Barrier ◽  
Strong Winds

A bridge, which is located in the route of typhoon, is considered how to assure normal traffic use against strong winds. As one of the measures, wind barrier is proposed to be set on both sides of the bridge section for reducing wind velocity across it. In this study, an analysis by using CFX, a computational fluid dynamics program, is carried out to investigate the effects of wind barrier. The speed of wind is assumed as 60m/s. To find out an efficient design of the boards, different porosity ratios(r) of the boards is assumed for comparison. The result shows that wind barrier could reduce the wind speed across the bridge effectively.

Energy efficient design of high depth raceway pond using computational fluid dynamics

2019 ◽  
Vol 133 ◽  
pp. 528-537 ◽  
Author(s):  
S.S. Sawant ◽  
S.N. Gosavi ◽  
H.P. Khadamkar ◽  
C.S. Mathpati ◽  
Reena Pandit ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Energy Efficient ◽  
Efficient Design ◽  
Raceway Pond ◽  
Energy Efficient Design ◽  
High Depth

scholarly journals Integrating Animated Computational Fluid Dynamics into Mixed Reality for Building-Renovation Design

Technologies ◽  
2019 ◽  
Vol 8 (1) ◽  
pp. 4 ◽  
Author(s):  
Yuehan Zhu ◽  
Tomohiro Fukuda ◽  
Nobuyoshi Yabuki
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Change Process ◽  
Mixed Reality ◽  
Thermal Environment ◽  
Integrated System ◽  
Prototype System ◽  
Efficient Manner ◽  
Thermal Change ◽  
Head Mounted Display

In advanced society, the existing building stock has a high demand for stock renovation, which gives existing buildings new lives, rather than building new ones. During the renovation process, it is necessary to simultaneously achieve architectural, facilities, structural, and environmental design in order to accomplish a healthy, comfortable, and energy-saving indoor environment, prevent delays in problem-solving, and achieve a timely feedback process. This study tackled the development of an integrated system for stock renovation by considering computational fluid dynamics (CFD) and mixed reality (MR) in order to allow the simultaneous design of a building plan and thermal environment. The CFD analysis enables simulation of the indoor thermal environment, including the entire thermal change process. The MR system, which can be operated by voice command and operated on head-mounted display (HMD), enables intuitive visualization of the thermal change process and, in a very efficient manner, shows how different renovation projects perform for various stakeholders. A prototype system is developed with Unity3D engine and HoloLens HMD. In the integrated system, a new CFD visualization method generating 3D CFD animation sequence for the MR system is proposed that allows stakeholders to consider the entirety of changes in the thermal environment.

Computational Fluid Dynamics Evaluations of Unconventional Film Cooling Scaling Parameters on a Simulated Turbine Blade Leading Edge

2014 ◽  
Vol 136 (10) ◽  
Author(s):  
James L. Rutledge ◽  
Marc D. Polanka
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Heat Capacity ◽  
Reynolds Number ◽  
Turbine Blade ◽  
Film Cooling ◽  
Flux Ratio ◽  
Leading Edge ◽  
Density Effects ◽  
Number Ratio

While it is well understood that certain nondimensional parameters, such as freestream Reynolds number and turbulence intensity, must be matched for proper design of film cooling experiments; uncertainty continues on the ideal method to scale film cooling flow rate. This debate typically surrounds the influence of the coolant to freestream density ratio (DR) and whether mass flux ratio or momentum flux ratio properly accounts for the density effects. Unfortunately, density is not the only fluid property to differ between typical wind tunnel experiments and actual turbine conditions. Temperature differences account for the majority of the property differences; however, attempts to match DR through the use of alternative gases can exacerbate these property differences. A computational study was conducted to determine the influence of other fluid properties besides density, namely, specific heat, thermal conductivity, and dynamic viscosity. Computational fluid dynamics (CFD) simulations were performed by altering traditional film cooling nondimensional parameters as well as others such as the Reynolds number ratio, Prandtl number ratio, and heat capacity ratio (HCR) to evaluate their effects on adiabatic effectiveness and heat transfer coefficient. A cylindrical leading edge with a flat afterbody was used to simulate a turbine blade leading edge region. A single coolant hole was located 21.5 deg from the leading edge, angled 20 deg to the surface and 90 deg from the streamwise direction. Results indicated that thermal properties can play a significant role in understanding and matching results in cooling performance. Density effects certainly dominate; however, variations in conductivity and heat capacity can result in 10% or higher changes in the resulting heat flux to the surface when scaling ambient rig configurations to engine representative conditions.

Computational Investigation of the Effects of Piston Geometry on the Combustion Evolution in a Light Duty HSDI Engine

2017 ◽  
Author(s):  
Riyaz Ismail ◽  
Felix Leach ◽  
Martin H. Davy ◽  
David Richardson ◽  
Brian Cooper
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Combustion Chamber ◽  
Adaptive Mesh Refinement ◽  
Fuel Injection ◽  
Temporal Distribution ◽  
Adaptive Mesh ◽  
Test Point ◽  
Piston Bowl ◽  
Dynamics Simulations

The spatial and temporal distribution of fuel and air within the combustion chamber directly influences ignition, combustion and emissions formation in diesel engines. These fuel-air interactions are affected by details of the combustion chamber geometry and fuel injection parameters. This paper investigates the effects of piston bowl geometry and spray targeting on combustion behaviour in a single cylinder diesel engine. Closed cycle computational fluid dynamics simulations are performed on a sector mesh at various load points using the 3 Zones Extended Coherent Flame Model coupled with adaptive mesh refinement. The computational fluid dynamics model is validated experimentally at the baseline conditions at each test point after-which, parametric sweeps of bowl geometry, exhaust gas recirculation rate and nozzle tip protrusion are conducted. Results indicate that appropriately pairing fuel injection strategy and piston geometry is essential.

scholarly journals Numerical simulation of pollutant dispersion near obstacle based on k - ɛ turbulence closure scheme

2002 ◽  
Vol 24 (4) ◽  
pp. 219-235
Author(s):  
Duong Ngoc Hai ◽  
Nguyen The Duc
Keyword(s):  
Fluid Dynamics ◽  
Numerical Simulation ◽  
Schmidt Number ◽  
Recirculation Zone ◽  
Measurement Data ◽  
Pollutant Dispersion ◽  
Numerical Code ◽  
Closure Scheme ◽  
Turbulent Schmidt Number ◽  
Calculation Results

To simulate the wind field, pollutant transport and dispersion near an obstacle a numerical code based on the k - Ɛ turbulence model has been built. Beside the standerd k - Ɛ, two other modifications proposed by Detering & Etling and Duynkerke are also considered. The calculation results are verified based on the measurement data of von Karman Institute for Fluid Dynamics (Belgium). Modifications of the turbulent Schmidt number were carried out in order to match the measured results. The code was used to investigate the influence of the recirculation zone behind a building of cubical shape on the transport and disersion of pollutant. For a stack behind and near the obstacle, some conclusions about the effect of the stack height and stack location were derived.

scholarly journals The use of CFD in the evaluation of UV treatment systems

2001 ◽  
Vol 3 (2) ◽  
pp. 59-70 ◽  
Author(s):  
N. G. Wright ◽  
D. M. Hargreaves
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Three Dimensional ◽  
Grid Size ◽  
Design Tool ◽  
Uv Disinfection ◽  
Efficient Design ◽  
Uv Treatment ◽  
Sensitivity Tests ◽  
Computational Fluid Dynamics Cfd

UV disinfection is now widely used for the treatment of water for consumption and wastewater in many countries. It offers advantages over other techniques in specific circumstances. Analysis of these systems has been carried out using a three-dimensional Computational Fluid Dynamics (CFD) procedure. This allows for efficient testing of prototypes. Sensitivity tests are shown for grid size, discretisation and turbulence model. Four different configurations of the apparatus are evaluated in terms of maximum dosage, flow patterns, particle tracks and transient dosage. This leads to conclusions about the most efficient design and shows that significant improvements can be achieved with minor changes to the design. Further conclusions are drawn about the CFD procedure itself. This work opens up the possibility of an internet-based design tool for small- and medium-sized enterprises.

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