scholarly journals Modelling Combustion Instabilities Using Computational Fluid Dynamics

1999 ◽  
Author(s):  
Steve J. Brookes ◽  
R. Stewart Cant ◽  
Ann P. Dowling
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Heat Release ◽  
Structural Damage ◽  
Bluff Body ◽  
Turbulent Transport ◽  
Premixed Combustion ◽  
Forced Oscillations ◽  
Combustion Heat ◽  
Combustion Systems

The drive for lower emissions has forced combustor designers to consider lean premixed combustion systems. Unfortunately, premixed combustion systems are particularly susceptible to instabilities, raising large periodic fluctuations in heat release and pressure, that may cause structural damage. A reliable computational tool for predicting the onset of these oscillations would be extremely useful during the design process. The work contained in this paper utilises computational fluid dynamics to model a simple premixed combustor, consisting of a bluff-body stabilised flame burning within a cylindrical duct. State of the art models are used to represent the combustion heat release and the turbulent transport within the combustor. Both forced oscillations and a nearly self-excited condition are modelled and compared with experiment.

Computational Modelling of Self-Excited Combustion Instabilities

2000 ◽  
Author(s):  
Steve J. Brookes ◽  
R. Stewart Cant ◽  
Iain D. J. Dupere ◽  
Ann P. Dowling
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Heat Release ◽  
Large Scale ◽  
Computational Modelling ◽  
Combustion Efficiency ◽  
Design Tool ◽  
Premixed Combustion ◽  
Combustion Instabilities ◽  
Combustion Systems

It is well known that lean premixed combustion systems potentially offer better emissions performance than conventional non-premixed designs. However, premixed combustion systems are more susceptible to combustion instabilities than non-premixed systems. Combustion instabilities (large-scale oscillations in heat release and pressure) have a deleterious effect on equipment, and also tend to decrease combustion efficiency. Designing out combustion instabilities is a difficult process and, particularly if many large-scale experiments are required, also very costly. Computational fluid dynamics (CFD) is now an established design tool in many areas of gas turbine design. However, its accuracy in the prediction of combustion instabilities is not yet proven. Unsteady heat release will generally be coupled to unsteady flow conditions within the combustor. In principle, computational fluid dynamics should be capable of modelling this coupled process. The present work assesses the ability of CFD to model self-excited combustion instabilities occurring within a model combustor. The accuracy of CFD in predicting both the onset and the nature of the instability is reported.

Computational Modeling of Self-Excited Combustion Instabilities

2001 ◽  
Vol 123 (2) ◽  
pp. 322-326 ◽  
Author(s):  
S. J. Brookes ◽  
R. S. Cant ◽  
I. D. J. Dupere ◽  
A. P. Dowling
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Heat Release ◽  
Large Scale ◽  
Combustion Efficiency ◽  
Design Tool ◽  
Premixed Combustion ◽  
Combustion Instabilities ◽  
Lean Premixed Combustion ◽  
Combustion Systems

It is well known that lean premixed combustion systems potentially offer better emissions performance than conventional non-premixed designs. However, premixed combustion systems are more susceptible to combustion instabilities than non-premixed systems. Combustion instabilities (large-scale oscillations in heat release and pressure) have a deleterious effect on equipment, and also tend to decrease combustion efficiency. Designing out combustion instabilities is a difficult process and, particularly if many large-scale experiments are required, also very costly. Computational fluid dynamics (CFD) is now an established design tool in many areas of gas turbine design. However, its accuracy in the prediction of combustion instabilities is not yet proven. Unsteady heat release will generally be coupled to unsteady flow conditions within the combustor. In principle, computational fluid dynamics should be capable of modeling this coupled process. The present work assesses the ability of CFD to model self-excited combustion instabilities occurring within a model combustor. The accuracy of CFD in predicting both the onset and the nature of the instability is reported.

Numerical Simulation on Spreading Characteristic of Coach Fire

2012 ◽  
Vol 518-523 ◽  
pp. 1269-1272 ◽  
Author(s):  
Liang Yi ◽  
Jie Chen
Keyword(s):  
Fluid Dynamics ◽  
Numerical Simulation ◽  
Computational Fluid Dynamics ◽  
Heat Release ◽  
Heat Release Rate ◽  
Fire Protection ◽  
Release Rate ◽  
Software Package ◽  
Maximum Temperature ◽  
Peak Heat Release Rate

The aim of this work is to study the burning characteristics of coach fire. With application of computational fluid dynamics (FDS software package), coach fires caused by arson are simulated under different ventilation conditions. Variation of heat release rate (HRR) and distribution of temperature are analyzed. Peak heat release rate of coach fire caused by arson in passenger carriage can reach about 24 MW and maximum temperature in the carriage is over 1000 °C. Results of this study can be referred for fire protection and rescue design of coach.

Using Computational Fluid Dynamics Simulation to Perform Fire Investigation

2013 ◽  
Vol 393 ◽  
pp. 845-850 ◽  
Author(s):  
Mohammad Shakir Nasif ◽  
Rafat Al-Waked
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Detection System ◽  
Dynamics Simulation ◽  
Smoke Inhalation ◽  
Fire Investigation ◽  
Dynamic Simulator

Fire occurred evening 10thJuly 1989 at Terwindle Rest Home Auckland. Incident report shows that this fire resulted in seven fatalities and extensive fire damage to the building. The primary cause of the death was carbon monoxide poising from smoke inhalation. The fire started at the lounge which contained ten upholstered couches with polyurethane foam padding. Sprinkler fire protection system was not installed and the building has no smoke detection system (based on the New Zealand Building code requirement that was imposed at that time). In this study, the fire is modeled using Computational Fluid Dynamics (CFD) software FDS (Fire Dynamic Simulator). The heat release rate of the fuel burned was obtained from lab measurement of a sofa. The results were validated against the approximate time scale of the progress of the fire as it was found from the fire investigation report. It has been found that FDS can provide accurate simulation to the fire which can be used to perform fire investigation provided that the correct heat release rate of the fire used in the model.

Computational Fluid Dynamics Simulations of the Container Express as a Helicopter Slung Load

2003 ◽  
Author(s):  
Misty G. Berry
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Reynolds Number ◽  
Vortex Shedding ◽  
Bluff Body ◽  
Practical Applications ◽  
Rectangular Cylinder ◽  
Wind Tunnel Data ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations

Flow over rectangular boxes and cylinders has not been well studied, and yet has numerous practical applications. This bluff-body geometry causes immediate flow separation and periodic vortex shedding in the wake of the object, regardless of Reynolds number. This paper presents the use and verification of a CFD methodology for predicting the forces on a particular rectangular cylinder—a slung load cargo container known as a Container Express (CONEX). It presents a comparison of the numerically obtained forces to wind tunnel data for the CONEX that demonstrates ranges of validity for the simulations. These comparisons give confidence for force and moment results for CONEX and vertical stabilizer simulations. The forces and moments will be used to design a mounting system for the vertical stabilizer.

Simulation of Combustion Process in Diesel Engines Based on Eddy Dissipation Model

2016 ◽  
Vol 823 ◽  
pp. 315-318
Author(s):  
Mahran Dawwa
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Combustion Chamber ◽  
Diesel Engines ◽  
Combustion Process ◽  
Premixed Combustion ◽  
Dissipation Model ◽  
Simulation Results ◽  
Dynamics Method

The aim of this study is to simulate the combustion process in the combustion chamber of diesel engines by using eddy dissipation model (EDM) and computational fluid dynamics method (CFD). Computational fluid dynamics has been used wieldy in the recent years for simulating the strokes of diesel engines including the combustion process. Eddy dissipation model can be used for simulating non-premixed combustion cases such as the combustion in diesel engines. The simulation steps and the simulation results will be discussed and illustrated. ANSYS program is the software which used for performing this simulation.

Computational Fluid Dynamics Model for Tacoma Narrows Bridge Upgrade Project

2003 ◽  
Author(s):  
Kristian Debus ◽  
Jonathan Berkoe ◽  
Brigette Rosendall ◽  
Farzin Shakib
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Computational Model ◽  
Bluff Body ◽  
Dynamics Model ◽  
Computational Fluid Dynamics Model ◽  
Flow Past ◽  
Anchoring System ◽  
Tacoma Narrows Bridge

The purpose of this work was to validate and apply a commercial computational fluid dynamics code with a hybrid RANS/LES turbulence computational model for a flow past a bluff body ultimately to help in the design of the caisson anchoring system during construction of a new adjacent span of the Tacoma Narrows Bridge.

Drag Reduction of Tractor-Trailers Using Optimized Add-On Devices

2010 ◽  
Vol 132 (8) ◽  
Author(s):  
Fu-Hung Hsu ◽  
Roger L. Davis
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Drag Coefficient ◽  
Body Shape ◽  
Bluff Body ◽  
Navier Stokes ◽  
Optimized Design ◽  
Design Strategies ◽  
Body Design ◽  
Previous Idea

Tractor-trailers have a higher drag coefficient than other vehicles due to their bluff-body shape. Numerous add-on devices have been invented to help reduce drag and fuel consumption. The current research extends our previous idea of add-on humps and investigates their effect in conjunction with curved boat-tail flaps. Computational fluid dynamics in the form of unsteady Reynolds-averaged Navier–Stokes and detached-eddy simulations were used to determine viable design strategies. A 3D baseline computational model was constructed using an Ahmed body. Design optimization was applied on the new add-on devices. The results from the optimized design were shown to have a 50.9% reduction in drag coefficient.

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