High SI engine part load efficiencies require simultaneously part load dethrottling and small burn durations. The latter ones necessitate – in case of SI combustion in its prevalent appearance – minimum residual burnt gas and high in-cylinder turbulence generated by charge motion. These demands can especially be fulfilled by variable valve trains with asymmetric valve actuation, also called intake valve lift phasing with intake port deactivation as its borderline case. They can combine early intake valve closing and strong charge motion generation, which contains both tumble and swirl.
In order to enable phenomenological burn rate prediction via 0D/1D engine simulation for these cases, a quasi-dimensional charge motion and turbulence model has been developed. The generation of charge motion is modeled by use of charge motion coefficients which should be derived from at least one engine operation point calculated by 3D-CFD. The conversion of tumble and swirl to turbulence around top dead center is predicted by a quasi-dimensional flow shear model.
An additional model part is also presented considering an approach for the impact of direct fuel injection on tumble and turbulence. The model development was based on 3D CFD simulations.
A Quasi-Dimensional Charge Motion and Turbulence Model for Spark Injection Engines with Fully Variable Valve Train and Direct Fuel Injection
Proceedings
Experten-Forum Powertrain: Ladungswechsel und Emissionierung 2019 ; Chapter : 3 ; 24-39
2020-01-27
16 pages
Article/Chapter (Book)
Electronic Resource
German
British Library Conference Proceedings | 2018
|SAE Technical Papers | 2018
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