Download or read book Combustion Modelling in Spark ignition Engines Using Conditional Source term Estimation written by Girish Venkata Nivarti and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Investigation of Conditional Source term Estimation Approach for Turbulent Partially Premixed Combustion Modelling written by Daniele Dovizio and published by . This book was released on 2015 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: Conditional Source-term Estimation (CSE) is a closure technique for modelling turbulent combustion phenomena. CSE uses the Conditional Moment Closure (CMC) hypothesis for closing chemical source terms: conditionally averaged chemical source terms are closed by conditional averaged scalars, which are obtained by inverting an integral equation, instead of solving transport equations (as in CMC). Since CSE has been successfully applied to both premixed and non-premixed configurations, it represents an attractive method for dealing with the more general and complex case of partially premixed combustion. The objectives of the present study are to (i) consolidate the premixed formulation of CSE through numerical simulations of a turbulent bluff body premixed flame; (ii) formulate, implement and test the Doubly conditional CSE (DCSE) in the context of partially premixed combustion; (iii) compare the DCSE predictions with well documented turbulent partially premixed flames. The canonical example of partially premixed flames is represented by turbulent lifted flames. A series of lifted turbulent jet flames is investigated in RANS by using DCSE. The DCSE calculations are successful in predicting the lift-off heights at three different conditions and reproducing many aspects of the flame structure in agreement with the experimental observations. The current results show that important aspects of the stabilization mechanism can be reproduced by the DCSE combustion model. The applicability of DCSE is further evaluated by applying this approach to a series of turbulent V-shaped flames for which experimental data is available. Premixed and stratified conditions are investigated. Overall, the agreement between numerical results and experimental findings is good, demonstrating the capability of DCSE to deal with partially premixed combustion. Future work includes implementation of CSE in LES and investigation of different fuels such as propane and biofuels.

Download or read book Investigation of Conditional Source term Estimation Approach to Modelling Mild Combustion written by Jeffrey Labahn and published by . This book was released on 2016 with total page 161 pages. Available in PDF, EPUB and Kindle. Book excerpt: Conditional Source-term Estimation (CSE) is a turbulent combustion model which uses conditional averages to provide closure for the mean chemical source term and is based on the same ideas as the Conditional Moment Closure (CMC) approach. CSE applies first order closure for the conditional averages which are obtained by inverting an integral equation and has been used to simulate a range of premixed, non-premixed and partially premixed flames. In the present study, CSE is applied to investigate a high efficient, low emission combustion process called Moderate and Intense Low Oxygen Dilution (MILD) combustion. This work represents the first application of CSE for MILD combustion, the first application of a multi-stream CSE formulation and the first doubly-conditioned CSE formulation applied in the Large Eddy Simulation (LES) framework. The objectives of the present study are to i) investigate the CSE combustion model for turbulent non-premixed combustion, ii) develop a CSE formulation for MILD combustion problems, iii) implement CSE for MILD combustion problems in Reynolds-Averaged Navier-Stokes (RANS) and LES and iv) compare the CSE predictions to experimental and previous numerical results for well documented MILD combustion flames. Numerical simulations of a confined non-premixed methane flame are completed using the CSE non-premixed approach. This study investigates the sensitivity to various CSE model parameters and shows CSE is able to accurately predict non-premixed methane combustion. A detailed study of the inversion problem encountered in CSE is also investigated using the Bayesian framework. The origin of the perturbation seen in the unconditional mass fraction in CSE and the impact of a smoothing prior on the recovered solution and credible intervals are discussed. Different regularization methods are studied and it is shown that both zeroth and first order Tikhonov are promising regularization methods for CSE. In the present work, the non-premixed CSE formulation is extended to include the impact of radiation of the conditional reaction rates and is applied to a semi-industrial furnace. This study demonstrates that a RANS-CSE simulation is able to accurately predict the temperature and species concentration, including NOx, for large scale realistic furnace configurations. Finally, a multi-stream CSE formulation is developed and applied to the DJHC burners in the RANS and LES framework. This new CSE formulation is able to predict the temperature and velocity profiles in very good agreement with the experimental data. Further, the LES multi-stream CSE formulation is able to predict the time-dependent nature of the DHJC burners.

Download or read book Conditional Source term Estimation for Diesel Combustion written by Riyaz Ismail and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Quasi Dimensional Simulation of Spark Ignition Engines written by Alejandro Medina and published by Springer Science & Business Media. This book was released on 2013-08-20 with total page 201 pages. Available in PDF, EPUB and Kindle. Book excerpt: Based on the simulations developed in research groups over the past years, Introduction to Quasi-dimensional Simulation of Spark Ignition Engines provides a compilation of the main ingredients necessary to build up a quasi-dimensional computer simulation scheme. Quasi-dimensional computer simulation of spark ignition engines is a powerful but affordable tool which obtains realistic estimations of a wide variety of variables for a simulated engine keeping insight the basic physical and chemical processes involved in the real evolution of an automotive engine. With low computational costs, it can optimize the design and operation of spark ignition engines as well as it allows to analyze cycle-to-cycle fluctuations. Including details about the structure of a complete simulation scheme, information about what kind of information can be obtained, and comparisons of the simulation results with experiments, Introduction to Quasi-dimensional Simulation of Spark Ignition Engines offers a thorough guide of this technique. Advanced undergraduates and postgraduates as well as researchers in government and industry in all areas related to applied physics and mechanical and automotive engineering can apply these tools to simulate cyclic variability, potentially leading to new design and control alternatives for lowering emissions and expanding the actual operation limits of spark ignition engines

Download or read book Modelling Spark Ignition Combustion written by P. A. Lakshminarayanan and published by Springer Nature. This book was released on with total page 678 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Modelling Spark Ignition Combustion written by P. A. Lakshminarayanan and published by Springer. This book was released on 2024-05-02 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book provides a comprehensive overview of combustion models used in different types of spark ignition engines. In the first generation of spark ignition (SI) engines, the turbulence is created by the shear flow passing through the intake valves, and significantly decays during the intake and compression strokes. The residual turbulence enhances the laminar flame velocity, which is characteristic of the fuel and increases the relative effectiveness of the engine. In this simple two-zone model, the turbulence is estimated empirically; the spherical flame propagation model considers ignition delay, thermodynamics, heat transfer and chemical equilibrium, to obtain the performance and emissions of an SI engine. The model is used extensively by designers and research engineers to handle the fuel-air mixture prepared in the inlet and different geometries of open combustion chambers. The empiricism of the combustion model was progressively dismantled over the years. New 3D models for ignition considering the flow near a spark plug and flame propagation in the bulk gases were developed by incorporating solutions to Reynolds-averaged Navier-Stokes (RANS) equations for the turbulent flow with chemical reactions in the intense computational fluid dynamics. The models became far less empirical and enabled treating new generation direct-injection spark-ignition (DISI) gasoline and gas engines. The more complex layout of DISI engines with passive or active prechamber is successfully handled by them. This book presents details of models of SI engine combustion progressively increasing in complexity, making them accessible to designers, researchers, and even mechanical engineers who are curious to explore the field. This book is a valuable resource for anyone interested in spark ignition combustion.

Download or read book A Level Set Based Flamelet Model for the Prediction of Combustion in Homogeneous Charge and Direct Injection Spark Ignition Engines written by and published by Cuvillier Verlag. This book was released on 2006-03-01 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Modeling of End Gas Autoignition for Knock Prediction in Gasoline Engines written by Andreas Manz and published by Logos Verlag Berlin GmbH. This book was released on 2016-08-18 with total page 263 pages. Available in PDF, EPUB and Kindle. Book excerpt: Downsizing of modern gasoline engines with direct injection is a key concept for achieving future CO22 emission targets. However, high power densities and optimum efficiency are limited by an uncontrolled autoignition of the unburned air-fuel mixture, the so-called spark knock phenomena. By a combination of three-dimensional Computational Fluid Dynamics (3D-CFD) and experiments incorporating optical diagnostics, this work presents an integral approach for predicting combustion and autoignition in Spark Ignition (SI) engines. The turbulent premixed combustion and flame front propagation in 3D-CFD is modeled with the G-equation combustion model, i.e. a laminar flamelet approach, in combination with the level set method. Autoignition in the unburned gas zone is modeled with the Shell model based on reduced chemical reactions using optimized reaction rate coefficients for different octane numbers (ON) as well as engine relevant pressures, temperatures and EGR rates. The basic functionality and sensitivities of improved sub-models, e.g. laminar flame speed, are proven in simplified test cases followed by adequate engine test cases. It is shown that the G-equation combustion model performs well even on unstructured grids with polyhedral cells and coarse grid resolution. The validation of the knock model with respect to temporal and spatial knock onset is done with fiber optical spark plug measurements and statistical evaluation of individual knocking cycles with a frequency based pressure analysis. The results show a good correlation with the Shell autoignition relevant species in the simulation. The combined model approach with G-equation and Shell autoignition in an active formulation enables a realistic representation of thin flame fronts and hence the thermodynamic conditions prior to knocking by taking into account the ignition chemistry in unburned gas, temperature fluctuations and self-acceleration effects due to pre-reactions. By the modeling approach and simulation methodology presented in this work the overall predictive capability for the virtual development of future knockproof SI engines is improved.

Download or read book Source Term Evaluation for Combustion Modeling written by Myles A. Sussman and published by . This book was released on 1993 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Multiphysical Modelling of Regular and Irregular Combustion in Spark Ignition Engines Using an Integrated Interactive Flamelet Approach written by Linda Maria Beck and published by Logos Verlag Berlin. This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The virtual development of future Spark Ignition (SI) engine combustion processes in three-dimensional Computational Fluid Dynamics (3D-CFD) demands for the integration of detailed chemistry, enabling - additionally to the 3D-CFD modelling of flow and mixture formation - the prediction of fuel-dependent SI engine combustion in all of its complexity. This work presents an approach, which constitutes a coupled solution for flame propagation, auto-ignition, and emission formation modelling incorporating detailed chemistry, while exhibiting low computational costs. For modelling the regular flame propagation, a laminar flamelet approach, the G-equation is used. Auto-ignition phenomena are addressed using an integrated flamelet approach, which bases on the tabulation of fuel-dependent reaction kinetics. By introducing a progress variable for the auto-ignition - the Ignition Progress Variable (IPV) - detailed chemistry is integrated in 3D-CFD. The modelling of emission formation bases on an interactively coupled flamelet approach, the Transient Interactive Flamelet (TIF) model. The functionality of the combined approach to model the variety of SI engine combustion phenomena is proved first in terms of fundamentals and standalone sub-model functionality studies by introducing a simplified test case, which represents an adiabatic pressure vessel without moving meshes. Following the basic functionality studies, the sub-model functionalities are investigated and validated in adequate engine test cases. It is shown, that the approach allows to detect locally occurring auto-ignition phenomena in the combustion chamber, and to model their interaction with regular flame propagation. Moreover, the approach enables the prediction of emission formation on cell level.

Download or read book Cycle Simulation for a Spark Ignition Engine Using a Turbulent Combustion Model written by Kern Y. Kang and published by . This book was released on 1987 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Numerical Modelling of Fuel Injection and Stratified Turbulent Combustion in a Direct injection Spark ignition Engine Using an Open Source Code written by and published by . This book was released on 2014 with total page 279 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book TECHNICAL REPORT 1 SPARK IGNITION ENGINE SIMULATION MODELS written by C. BORGNAKKE, P. PUZINAUSKAS, Y. XIAO and published by . This book was released on 1986 with total page 74 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Multidimensional Modeling of Combustion and Knock in Spark ignition Engines with Detailed Chemical Kinetics written by Long Liang and published by . This book was released on 2006 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Spark Ignition Internal Combustion Engine Modelling Using Matlab written by David R. Buttsworth and published by . This book was released on 2002 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Cycle By Cycle Variation in Spark Ignition Internal Combustion Engines written by and published by . This book was released on 1999 with total page 253 pages. Available in PDF, EPUB and Kindle. Book excerpt: The primary objective of this work was to extend the engine cycle simulation used by the Oxford Internal Combustion Engine Group to enable it to perform cycle-by-cycle modelling. A literature review concluded that the most appropriate metric for quantifying the cyclic variation was the coefficient of variation of the indicated mean effective pressure, and that for zero dimensional computer simulations, the most sensible parameter to perturb for cycle-by-cycle modelling was the burn rate. Modelling attempts using burn rate information alone resulted in an under-prediction of the cyclic variability exhibited by the engine. The work then examined a two-zone polytropic process model in an attempt to improve burn rate estimation. The model proved unreliable for burn rate calculations. The Rassweiler and Withrow method was then modified to include both the compression and expansion indices throughout the combustion period. The technique proved viable, but was not used because the slow burn up of the significant crevice mass in the experimental engine made calculation of an accurate expansion index doubtful. A further cause of the under-prediction in cyclic variability was postulated to be incomplete combustion, which is not detected by the burn rate model. A completeness of combustion parameter was derived from information contained in the Rassweiler and Withrow analysis. This parameter was used along with burn rate variations to perturb the cycle simulation and resulted in good cycle-by-cycle agreement between the experimental data and the modelled data in terms of mean effective pressure, maximum pressure, and the phasing of maximum pressure. Cyclic measurements of NO showed that the technique did not predict the cyclic variability in NO formation, and this was attributed to the sensitivity of NO formation to parameters that were not allowed to vary on a cyclic basis within the model (such as residuals).