Real fuel chemistry facilitates accurate clean engine design

October 18, 2012 // By Bernie Rosenthal, Reaction Design
Today’s engine designs are increasingly dependent on the ability to exploit fuel behavior and control combustion to improve performance and emissions. Engines have to comply with tighter emissions regulations, including soot particle size, changing fuel combinations and global differences in the make-up of fuels as well as future fuels. The ability to accurately predict what happens when fuel is ignited in a combustion chamber still puzzles engine designers. Reaction Design's software enables car designers manufacturers to automate the analysis of chemical processes via computer simulation and modeling solutions.

Accurate, fast chemistry simulation is required for predictive to predict ignition calculations, predictive engine knock simulations and predictive emissions calculationsin engines. The RD software package robustly and accurately simulates engine-cylinder combustion performance for reciprocating engines, with virtually any fuel, helping engineers rapidly design clean, high-efficiency, fuel-flexible engines. Engine simulation applications include spark ignitiongasoline, diesel, and advanced designs such as Homogeneous Charge Compression Ignition (HCCI), PCI and PPCI [PCCI?], multiple fuel injections and dual-fuel engines.

The process by which fuel ignites and burnsof combustion can be modeled effectively using a detailed chemical mechanism of the fuel describing the thousands of short-lived species and chemical reactions that dictate how a fuel ignites, how the flame propagates, and how emissions like NOx, CO, and soot are formed. Accurately modeling real fuel behavior requires more chemistry than traditional Computational Fluid Dynamics (CFD) approaches can handle with acceptable time-to-solution. As most commercial CFD improvements directed toward better accuracy have focused on enhancing meshing and turbulence modeling, there has been little effort directed toward improving the fundamental chemistry calculations, to reflect the key engine behaviors that are now beginning to dominate the design space. Given that chemistry calculation times in CFD can account for 90% of the total simulation time even when employing severely reduced mechanisms, there is substantial opportunity for decreasing time-to-solution by accelerating these calculations.

 Visualization of the combustion process in a diesel engine

FORTÉ is a comprehensive CFD package that allows the engine designer to go directly from CAD drawings to simulation results in far less time than other CFD software, while taking advantage of real fuel chemistry models for better results without the need for expert calibration. Accurate modeling of realistic fuel effects is viable with superior time-to-solution metrics that fit in commercial-development timeframes. FORTÉ employs a novel solver approach that takes advantage of the chemical similarity of groups of cells and implements a parallel processing algorithm to dramatically reduce the chemistry

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