Knock detection in a quasi-dimensional SI combustion simulation using ignition delay and knock combustion modeling

Quasi-dimensional (QD) modeling of combustion in spark-ignition (SI) engines allows to describe the most relevant processes of heat release. Here, a submodel for the ignition delay is introduced and applied. The start of combustion is considered from ignition to the crank angle of 5% burned gas fraction. The introduced physical approach identifies the turbulent propagation velocity of the initiated kernel by taking into account early flame expansion and geometric restrictions of the flame propagation. The model is applied to stationary operation within an entire engine map of a turbocharged direct injection SI engine with fully variable valvetrain. Based on provided cycle-averaged input data, the model delivers good results within the margins of measured cycle-to-cycle fluctuations. Thus, it contributes to the assessment of the interplay between engine, engine control unit, drivetrain, and vehicle dynamics, hence making a step toward optimization and virtual engine calibration.

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Towards Integrated Spark and Combustion Modeling for Engines

ASME 2020 Internal Combustion Engine Division Fall Technical Conference ◽

10.1115/icef2020-2934 ◽

2020 ◽

Author(s):

Anand Karpatne ◽

Vivek Subramaniam ◽

Sachin Joshi ◽

Xiao Qin ◽

Douglas Breden ◽

...

Keyword(s):

Cross Flow ◽

Electrical Energy ◽

Combustion Model ◽

Consistent Estimate ◽

Combustion Kinetics ◽

Flame Kernel ◽

Combustion Modeling ◽

Combustion Simulation ◽

Coupling Strategy ◽

Ignition And Combustion

Abstract Combustion and emission performance of internal combustion (IC) engines depend on the ability of the ignition system to provide an ignition kernel that can successfully transition into an early flame kernel. Several key physical phenomena such as flow physics, plasma dynamics, circuit transients, and electromagnetics influence the behavior of the spark. The combustion kinetics decide the eventual transition of the spark into a self-sustaining flame kernel. The goal of this paper is to present a feasibility study involving the integration of a high-fidelity magnetohydrodynamic description of the spark physics with a finite rate chemical kinetics-based combustion model. A future goal of this proposed framework will be to model and validate a coupled ignition and combustion simulation for spark ignited engines. Two separate solvers are used to model spark physics and combustion kinetics respectively, and a coupling strategy is developed to model different aspects of physics occurring at disparate time-scales. This approach provides a physically consistent estimate of the electrical energy distribution within the spark-gap under high cross-flow velocities. When provided with certain favorable in-cylinder conditions, the spark kernel triggers self-sustained combustion.

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An Experimental and Modeling Study Into Using Normal and Isocetane Fuel Blends as a Surrogate for a Hydroprocessed Renewable Diesel Fuel

Journal of Energy Resources Technology ◽

10.1115/1.4027408 ◽

2014 ◽

Vol 136 (3) ◽

Cited By ~ 11

Author(s):

Jim Cowart ◽

Michael Raynes ◽

Len Hamilton ◽

Dianne Luning Prak ◽

Marco Mehl ◽

...

Keyword(s):

Ignition Delay ◽

Kinetic Mechanism ◽

Chemical Kinetic ◽

Renewable Diesel ◽

Binary Blend ◽

Combustion Modeling ◽

Fuel Blends ◽

Single Cylinder Engine ◽

Engine Testing ◽

Detailed Chemical

A new hydroprocessed renewable diesel (HRD) fuel comprised both straight chain and branched alkane fuel components. In an effort to find a research surrogate for this fuel, single cylinder engine testing was performed with various blends of n-hexadecane (cetane) and isocetane in order to find a binary surrogate mixture with similar performance characteristics to that of the HRD. A blend of approximately two-thirds n-hexadecane with one-third isocetane showed the most similar behavior based on conventional combustion metrics. Companion combustion modeling was then pursued using a combined detailed chemical kinetic mechanism for both n-hexadecane and isocetane. These modeling results show both the importance of isocetane in lengthening ignition delay (IGD), as well as the overall importance of chemical ignition delay as the dominating effect in the overall ignition delay of these binary blend fuels.

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An Experimental and Modeling Study Into Using Normal and ISO Cetane Fuel Blends as a Surrogate for a Hydro-Processed Renewable Diesel (HRD) Fuel

Volume 2: Fuels; Numerical Simulation; Engine Design, Lubrication, and Applications ◽

10.1115/icef2013-19056 ◽

2013 ◽

Cited By ~ 3

Author(s):

Jim Cowart ◽

Michael Raynes ◽

Len Hamilton ◽

Dianne Luning Prak ◽

Marco Mehl ◽

...

Keyword(s):

Ignition Delay ◽

Kinetic Mechanism ◽

Chemical Kinetic ◽

Renewable Diesel ◽

Binary Blend ◽

Combustion Modeling ◽

Fuel Blends ◽

Single Cylinder Engine ◽

Engine Testing ◽

Detailed Chemical

A new Hydro-processed Renewable Diesel (HRD) fuel is comprised of both straight chain and branched alkane fuel components. In an effort to find a research surrogate for this fuel, single cylinder engine testing was performed with various blends of n-hexadecane (cetane) and isocetane in order to find a binary surrogate mixture with similar performance characteristics to that of the HRD. A blend of approximately two-thirds n-hexadecane with one-third isocetane showed the most similar behavior based on conventional combustion metrics. Companion combustion modeling was then pursued using a combined detailed chemical kinetic mechanism for both n-hexadecane and isocetane. These modeling results show both the importance of isocetane in lengthening ignition delay, as well as the overall importance of chemical ignition delay as the dominating effect in the overall ignition delay of these binary blend fuels.

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