Multi Fuel Cylinder Head Development for Commercial Powertrains defined by Charge Motion Design
摘要
Alongside well-established alternative fuels like Natural Gas, Hydrogen, Methanol and Ammonia are driving decarbonization activities in the commercial sector. With the aim of integrating these different fuels into the portfolio and at the same time keeping production and assembly costs to a minimum, the goal is to develop multi-fuel capable cylinder heads. These multi-fuel cylinder heads need not only a flexible injector installation, but also the charge motion for homogeneous mixture formation and turbulence required for the premixed combustion. FEV’s Charge Motion Design (CMD) process, a benchmark and CFD-driven toolchain, enables the layout of the port design & combustion chamber to optimize the premixed combustion. It utilizes the geometrical and flow performance benchmarks and transient in-cylinder CFD and analyzes the key performance indicators based on charge motion and turbulence to assess the quality of the layout. The CMD process can estimate the burn delay for different fuels by analyzing the conditions at the spark plug by utilizing engine-validated correlations for the individual fuels. The burn duration is estimated by analyzing the mixture distribution and turbulence in the entire combustion chamber and employing the equations for the turbulent velocity for the individual fuels. The CMD analysis is used to present the various approaches to the port layout considering the orientation of the valves, the valve train concept and commonly used cylinder head bolting patterns. The discussion around the choice of flat roof vs pent roof cylinder head and predominant charge motion is elaborated considering the insights derived from the CMD analysis.