Combustion Science and Technology 

About: Combustion Science and Technology is an academic journal published by Taylor & Francis. The journal publishes majorly in the area(s): Combustion & Premixed flame. It has an ISSN identifier of 0010-2202. Over the lifetime, 5955 publications have been published receiving 149644 citations. The journal is also known as: Combust. Sci. Technol..

Simplified Reaction Mechanisms for the Oxidation of Hydrocarbon Fuels in Flames

Abstract: Simplified reaction mechanisms for the oxidation of hydrocarbon fuels have been examined using a numerical laminar flame model. The types of mechanisms studied include one and two global reaction steps as well as quasi-global mechanisms. Reaction rate parameters were varied in order to provide the best agreement between computed and experimentally observed flame speeds in selected mixtures of fuel and air. The influences of the various reaction rate parameters on the laminar flame properties have been identified, and a simple procedure to determine the best values for the reaction rate parameters is demonstrated. Fuels studied include n-paraffins from methane to n-decane, some methyl-substituted n-paraffins, acetylene, and representative olefin, alcohol and aromatic hydrocarbons. Results show that the often-employed choice of simultaneous first order fuel and oxidizer dependence for global rate expressions cannot yield the correct dependence of flame speed on equivalence ratio or pressure and can...

Turbulence Modeling of Internal Combustion Engines Using RNG κ-ε Models

Abstract: The RNG κ-e turbulence model derived by Yakhot and Orszag (1986) based on the Renormalization Group theory has been modified and applied to variable-density engine flows in the present study. The original RNG-based turbulence transport approximations were developed formally for an incompressible flow. In order to account for flow compressibility the RNG e-equation is modified and closed through an isotropic rapid distortion analysis. Computations were made of engine compressing/expanding flows and the results were compared with available experimental observations in a production diesel engine geometry. The modified RNG κ-e model was also applied to diesel spray combustion computations. It is shown that the use of the RNG model is warranted for spray combustion modeling since the ratio of the turbulent to mean-strain time scales is appreciable due to spray-generated mean flow gradients, and the model introduces a term to account for these effects. Large scale flow structures are predicted which ar...

Experimental and Theoretical Study of Nitric Oxide Formation in Internal Combustion Engines

Abstract: The nonequilibrium formation of nitric oxide within the internal combustion engine cylinder is examined. A thermodynamic model which predicts the properties of the burnt and unburnt gases during the combustion process is developed. A set of reactions which govern the formation of nitric oxide is proposed, and rate equations for nitric oxide concentrations as a function of time in the post-flame gases are derived. The results of time-resolved measurements carried out on a CFR engine are described, where emitted light intensities at wavelengths selected to record radiation from the CO + O and NO + O continua were used to determine the nitric oxide concentration. The comparison between theoretical and experimental results for fuel-lean mixtures confirms that the important features of the model presented are correct.

Modelling of premixed laminar flames using flamelet-generated manifolds

Abstract: In order to reduce the computational cost of flame simulations, several methods have been developed during the last decades, which simplify the description of the reaction kinetics. Most of these methods are based on partial-equilibrium and steady-state assumptions, assuming that most chemical processes have a much smaller time scale than the flow time scale. These assumptions, however, give poor approximations in the ‘colder’ regions of a flame, where transport processes are also important. The method presented here, can be considered as a combination of two approaches to simplify flame calculations, i.e. a flamelet and a manifold approach. The method, to which we will refer as the Flamelet-Generated Manifold (FGM) method, shares the idea with flamelet approaches that a multi-dimensional flame may be considered as an ensemble of one-dimensional flames. The implementation, however, is typical for manifold methods: a low-dimensional manifold in composition space is constructed, and the thermo-chemical vari...

Flame Stretch and the Balance Equation for the Flame Area

Abstract: When a flame propagates in a nonuniform flow it experiences strain and curvature effects. The fractional rate of change of the flame area constitutes the flame stretch. This quantity is often used to describe the structure and extinction mechanisms of turbulent flames. It also occurs in many recent studies of premixed laminar flames. This article provides a unified view of this concept on the basis of a novel derivation of stretch in terms of strain rate and curvature. The flame stretch, the rate of change of the normal to the flame front and the rate of change of the curvature are deduced from a general transport theorem. As an illustration, the components of flame stretch are evaluated in the case of a direct numerical simulation of the interaction between a pair of vortices and a laminar flame. Another application of flame stretch concerns the determination of the available flame surface density. A balance equation is derived for this quantity and cast in various useful forms thus providing a ...