Published 12 issues per year
ISSN Print: 1044-5110
ISSN Online: 1936-2684
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THE SPRAY-INDUCED FLOW AND ITS EFFECT ON THE TURBULENT CHARACTERISTIC COMBUSTION TIME IN Dl DIESEL ENGINES
ABSTRACT
In direct-injection diesel engines the combustion process is strongly influenced by the turbulence of the spray-induced flow. This flow is transient in nature and, therefore, the equilibrium-based k-e-type turbulence models yield inaccurate predictions of the turbulence mixing time scales. This requires adjustments of the turbulence characteristic combustion time by means of the coefficient CM, in order to match experimental cylinder pressures of different engines. These adjustments are explained in terms of nonequilibrium turbulence behavior of the spray-induced flow. A relation between the spatially averaged equilibrium and nonequilibrium turbulence time scales is derived which leads to a scaling law between the different engines. In particular, the value of CM for one engine can be obtained from the optimum CM of another engine, provided the turbulence determining integral length scales are known. This scaling behavior has been demonstrated for four substantially different engines by comparing the tuned values of CM with the computed scaling factors, and favorable agreement has been obtained.
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Macek Jan, Vítek Oldřich, Srinivasan Seshasai, Tanner Franz. X., 1-D Modeling of Transient Engine Operations Using Data Generated by a CFD Code, SAE Technical Paper Series, 1, 2008. Crossref
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Srinivasan Seshasai, Macek Jan, Polacek Milos, Tanner Franz X., Computational Optimization of a Split Injection System with EGR and Boost Pressure/Compression Ratio Variations in a Diesel Engine, SAE Technical Paper Series, 1, 2007. Crossref
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Tanner Franz X., Srinivasan Seshasai, Gradient-Based Optimization of a Multi-Orifice Asynchronous Injection System in a Diesel Engine Using an Adaptive Cost Function, SAE Technical Paper Series, 1, 2006. Crossref
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Macek Jan, Dolecek Vit, Srinivasan Seshasai, Tanner Franz, Vitek Oldrich, Optimization of Engine Control Strategies During Transient Processes Combining 1-D and 3-D Approaches, SAE Technical Paper Series, 1, 2010. Crossref
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Srinivasan Seshasai, Tanner Franz X., Macek Jan, Polacek Milos, Computational Optimization of Split Injections and EGR in a Diesel Engine Using an Adaptive Gradient-Based Algorithm, SAE Technical Paper Series, 1, 2006. Crossref
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Macek Jan, Vítek Oldřich, Doleček Vít, Srinivasan Seshasai, Tanner Franz X., Improved Simulation of Transient Engine Operations at Unsteady Speed Combining 1-D and 3-D Modeling, SAE Technical Paper Series, 1, 2009. Crossref
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Tanner F. X., Reacting Sprays, in Handbook of Atomization and Sprays, 2011. Crossref