Implementation and Validation of the Jet Flame Model Using C++ Open Source Codes Computational Fluid Dynamics Software

2015 ◽  
Vol 656-657 ◽  
pp. 676-681 ◽  
Author(s):  
Panit Kamma ◽  
Chakrit Suvanjumrat
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Open Source ◽  
Turbulence Model ◽  
Mixture Fraction ◽  
Average Error ◽  
Jet Flame ◽  
Source Codes ◽  
Eddy Simulation ◽  
Fast Chemistry

The open source code software, OpenFOAM, based on the computational fluid dynamics (CFD) was implemented to simulate the methane jet flame. The large eddy simulation (LES) of turbulence model was written using C++ language. The mixture fraction approach and infinitely-fast chemistry assumption was combined with this LES turbulence model. The results of jet flame simulation were validated with Yi Zeng etal., (2011) experiments based on flame lengths under flow rate and pressure conditions of 5.95-23.81 mg/s and 50-100 kPa, respectively. It was found that an average error of flame lengths obtained from the developed CFD model was 8.57% when referred the 1% O2 remaining was a flame shape.

Large-eddy simulation of the flow in a direct injection spark ignition engine using an open-source framework

2020 ◽  
pp. 146808742090362
Author(s):  
Mateus Dias Ribeiro ◽  
Alex Mendonça Bimbato ◽  
Maurício Araújo Zanardi ◽  
José Antônio Perrella Balestieri ◽  
David P Schmidt
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Large Eddy Simulation ◽  
Open Source ◽  
Direct Injection ◽  
Spark Ignition ◽  
Spark Ignition Engines ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Direct Injection Spark Ignition

Direct injection spark ignition engines aim at reducing specific fuel consumption and achieving the strict emission standards in state of the art internal combustion engines. This can be achieved by research comprising experimental methods, which are normally expensive and limited, and computational fluid dynamics methods, which are often more affordable and less restricted than their experimental counterpart. In the latter approach, the costs are mainly related to the acquisition, usage, and maintenance of computational resources, and the license cost when commercial computational fluid dynamics codes are used. Therefore, in order to make the research of direct injection spark ignition engines and their internal processes more accessible, this article proposes a novel open-source and free framework based on the OpenFOAM computational fluid dynamics library for the simulation of the internal flow in direct injection spark ignition engines using a large-eddy simulation closure for modeling the turbulence within the gas phase. Finally, this framework is tested by simulating the Darmstadt engine in motored operation, validating the results with experimental data compiled by the Darmstadt Engine Workshop.

Analysis of an Airfoil Using a Transition and Turbulence Model

2016 ◽  
Vol 819 ◽  
pp. 356-360
Author(s):  
Mazharul Islam ◽  
Jiří Fürst ◽  
David Wood ◽  
Farid Nasir Ani
Keyword(s):  
Fluid Dynamics ◽  
Boundary Layer ◽  
Computational Fluid Dynamics ◽  
Kinetic Energy ◽  
Turbulence Model ◽  
Original Version ◽  
Transitional Region ◽  
Cfd Analysis ◽  
Computational Fluid Dynamics Cfd

In order to evaluate the performance of airfoils with computational fluid dynamics (CFD) tools, modelling of transitional region in the boundary layer is very critical. Currently, there are several classes of transition-based turbulence model which are based on different methods. Among these, the k-kL- ω, which is a three equation turbulence model, is one of the prominent ones which is based on the concept of laminar kinetic energy. This model is phenomenological and has several advantageous features. Over the years, different researchers have attempted to modify the original version which was proposed by Walter and Cokljat in 2008 to enrich the modelling capability. In this article, a modified form of k-kL-ω transitional turbulence model has been used with the help of OpenFOAM for an investigative CFD analysis of a NACA 4-digit airfoil at range of angles of attack.

Reactive computational fluid dynamics modelling methane–hydrogen admixtures in internal combustion engines part II: Large eddy simulation

2020 ◽  
pp. 146808742091034
Author(s):  
Jann Koch ◽  
Christian Schürch ◽  
Yuri M Wright ◽  
Konstantinos Boulouchos
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Large Eddy Simulation ◽  
Combustion Process ◽  
Flame Speed ◽  
Hydrogen Addition ◽  
Eddy Simulation ◽  
Modelling Framework ◽  
Large Eddy ◽  
Dynamics Modelling

Fuels based on admixtures of methane/natural gas and hydrogen are a promising way to reduce CO2 emissions of spark ignition engines and increase their efficiency. A lot of work was conducted experimentally, whereas only limited numerical work is available in the context of three-dimensional modelling of the full engine cycle. This work addresses this fact by proposing a reactive computational fluid dynamics modelling framework to consider the effects of hydrogen addition on the combustion process. Part I of this two-part study focuses on the modelling and crucial considerations in order to predict the mean cycle based on the G-equation combustion model using the Reynolds-averaged Navier–Stokes equations. There, the effect of increased burning speed was globally captured by increasing the flame speed coefficient A, appearing in the considered flame speed closure. The proposed simplified modelling of the early flame stage proved to be robust for the conducted hydrogen variation from 0 to 50 vol% H2 for stoichiometric and lean operation. Scope of this work, Part II, are cyclic fluctuations and the hydrogen influence thereon using large eddy simulation and the proposed modelling framework. The model is probed towards its capabilities to predict the fluctuation of the combustion process for 0 and 50 vol% H2 and correlations influencing the observed peak pressure of the individual cycle are presented. It is shown that the considered approach is capable to reproduce the cyclic fluctuations of the combustion process under the influence of hydrogen addition as well as lean operation. The importance of the early flame phase with respect to arising fluctuations is highlighted as well as the contribution of the resolved scales in terms of the flame front wrinkling.

scholarly journals Effect of geometrical factors interactions on design optimization process of a natural gas ejector

2019 ◽  
Vol 11 (9) ◽  
pp. 168781401988036
Author(s):  
Amin Hassan Amin ◽  
Ibrahim Elbadawy ◽  
E Elgendy ◽  
M Fatouh
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Natural Gas ◽  
Optimum Design ◽  
Average Error ◽  
Minor Effect ◽  
Optimization Approach ◽  
Entrainment Ratio ◽  
Geometrical Factors ◽  
Discharge Pressure

Enhancing the ejector entrainment ratio plays an important role in the ejector performance. In this article, a surrogate-based optimization approach along with computational fluid dynamics technique has been employed to optimize the entrainment ratio of a single-phase ejector working with natural gas. Nine ejector geometrical factors have been varied to maximize the ejector entrainment ratio. Validation results of the presented computational fluid dynamics model were in a good agreement with the experimental data from the literature with an average error of 0.6% in the critical mode. Reported results showed that the optimum design achieves entrainment ratio of 19.45% at 12, 2, and 5.2 MPa motive pressure, induced pressure, and discharge pressure, respectively. Moreover, the primary nozzle convergent angle and throat length are insignificant factors. Furthermore, secondary nozzle inclination angle has a minor effect on the entrainment ratio of the optimum design.

Computational Fluid Dynamics Modeling of Mixed Convection Flows in Building Enclosures

2013 ◽  
Author(s):  
Alexander Kayne ◽  
Ramesh Agarwal
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Mixed Convection ◽  
Turbulence Model ◽  
Numerical Algorithm ◽  
Navier Stokes ◽  
Cfd Simulations ◽  
Flow And Heat Transfer

In recent years Computational Fluid Dynamics (CFD) simulations are increasingly used to model the air circulation and temperature environment inside the rooms of residential and office buildings to gain insight into the relative energy consumptions of various HVAC systems for cooling/heating for climate control and thermal comfort. This requires accurate simulation of turbulent flow and heat transfer for various types of ventilation systems using the Reynolds-Averaged Navier-Stokes (RANS) equations of fluid dynamics. Large Eddy Simulation (LES) or Direct Numerical Simulation (DNS) of Navier-Stokes equations is computationally intensive and expensive for simulations of this kind. As a result, vast majority of CFD simulations employ RANS equations in conjunction with a turbulence model. In order to assess the modeling requirements (mesh, numerical algorithm, turbulence model etc.) for accurate simulations, it is critical to validate the calculations against the experimental data. For this purpose, we use three well known benchmark validation cases, one for natural convection in 2D closed vertical cavity, second for forced convection in a 2D rectangular cavity and the third for mixed convection in a 2D square cavity. The simulations are performed on a number of meshes of different density using a number of turbulence models. It is found that k-epsilon two-equation turbulence model with a second-order algorithm on a reasonable mesh gives the best results. This information is then used to determine the modeling requirements (mesh, numerical algorithm, turbulence model etc.) for flows in 3D enclosures with different ventilation systems. In particular two cases are considered for which the experimental data is available. These cases are (1) air flow and heat transfer in a naturally ventilated room and (2) airflow and temperature distribution in an atrium. Good agreement with the experimental data and computations of other investigators is obtained.

Open-Source Computational Fluid Dynamics in Engineering Education

2019 ◽  
Author(s):  
Ivaylo Nedyalkov
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Engineering Education ◽  
Open Source ◽  
Code Base ◽  
Undergraduate Engineering Education ◽  
Computational Fluid Dynamics Cfd ◽  
The University ◽  
University Of New Hampshire ◽  
Mathematics And Physics

Abstract Computational Fluid Dynamics (CFD) is widely used in industry but is not discussed sufficiently in undergraduate engineering education. In some cases, CFD is studied only from a mathematical perspective, focusing on computational partial differential equations, and in some cases it is introduced as a black-box tool. A hybrid CFD class was developed for undergraduate and graduate students at the University of New Hampshire, which combines the two approaches. The students are exposed to the mathematics and physics behind CFD, and they also utilize OpenFOAM — an open source CFD package — to work on practical problems. Since the code is open-source, the students are able to see and modify it. Although OpenFOAM is challenging due to the minimum graphical user interface, the code-base environment forces the students to learn what the code is doing. Sample assignments and project submissions from the students are presented in the paper.

Investigation of vehicle stability under crosswind conditions based on coupling methods

2019 ◽  
Vol 233 (13) ◽  
pp. 3305-3317 ◽  
Author(s):  
Taiming Huang ◽  
Shuya Li ◽  
Zhongmin Wan ◽  
Zhengqi Gu
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Large Eddy Simulation ◽  
Coupling Method ◽  
Vehicle Stability ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Body Dynamics ◽  
Multi Body ◽  
Vehicle Movement

In this study, vehicle stability under crosswind conditions is investigated. A two-way coupling method is established based on computational fluid dynamics and vehicle multi-body dynamics. Large eddy simulation is employed in the computational fluid dynamics model to compute the transient aerodynamic load, and the accuracy of the large eddy simulation is validated with a wind tunnel experiment. The arbitrary Lagrange–Euler technique is used in the computational fluid dynamics simulation to realise vehicle motion, and a real-time data transmission method is employed to ensure effective exchange of data between the computational fluid dynamics and multi-body dynamics models. The robustness of the two-way coupling model is verified by changing the position of the vehicle centroid. The results of the two-way and one-way coupling simulations demonstrate that crosswinds significantly affect vehicle stability. There is a clear difference between the results obtained with the two methods, particularly after the disappearance of the crosswind. The main reason for the difference is that the interaction between the transient airflow and the vehicle movement is considered in the two-way coupling method. Therefore, investigations of vehicle stability under crosswind conditions should consider the coupling of transient aerodynamic force and vehicle movement.

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