Walter Huebner

Optimization of the trade-off between fuel consumption and performance of PHEVs in different driving scenarios

In [1] a new concept was developed for the design of hybrid electric powertrains that includes optimization of the component sizes as well as control strategies. In contrast to most existing publications, the approach explicitly considers the conflicting goals of low fuel consumption and high vehicle longitudinal dynamics and the trade-off is quantified. This is achieved by formulating two multiobjective optimization problems using the Pareto-concepts and solving it by using a Genetic Algorithm. Whereas results have already been shown for the New European Driving Cycle (NEDC) [1], this paper focuses on future driving scenarios that represent the markets USA, China and Germany. It is shown, how the control strategy and the component sizes of the electrical machine, the battery-pack and the final drive have to be adapted when considering driving cycles with different typical characteristics.

Fuel-stratification in automotive engines with vortical flow structures: An engineering approach with numerical and experimental methods

Publisher Summary This chapter investigates the numerical and experimental methods for direct injection of liquid fuel into the cylinder of an internal combustion engine. The flow field, fuel injection, and mixture formation of direct injection gasoline engines is simulated with a finite volume method for the complete intake and compression stroke. The injection of a conical liquid fuel jet directly into the combustion chamber creates vortical flow structures that interact with the in-cylinder flow. These induced vortical flow structures are “designed” as vortex rings to enhance the fuel-air mixing under full-load conditions and to expand the part-load range with a stratified charge near the spark plug. As an engineering approach, investigations are carried through for such a “spray-guided” combustion system with a two-equation model based on Reynolds-averaged conservation equations. Simulations are performed for simple spray-chamber geometry to study the vortex ring formation but also for realistic production engines. The results are compared with measurements from a spray-chamber and an engine with optical access using the method of laser-induced fluorescence of evaporated fuel.