Design and Simulation of a Multi Fuel Gas Mixture System of a Wankel Rotary Engine

The paper first includes the main objective and boundary conditions for design and simulation of a multi fuel gas mixture system of a Wankel rotary engine. New regenerative fuels are more and more important for use in automotive propulsion and stationary applications of combustion engines. Due to the special design and operation of rotary engines there are opportunities for running these engines in future electric and hybrid applications with new designed liquids and gaseous fuels based on regenerative energy sources. Nevertheless, rotary engines have advantages in avoidance of preignition and detonation especially when using gaseous fuels with a higher percentage of hydrogen. The focus is on basic research and analyses of main physical and thermodynamic properties of separate lean burn gases (lower calorific value, mixed calorific value, AFR) and their effects on fuel mixing and engine performance. Furthermore, the scope of the investigation is on the development of simulation models, which are capable to simulate the entire engine process and to map all factors influencing mixture formation, and for the combustion important parameter of unconventional gaseous fuels. Moreover, the authors compare analytical methods and modeling of the power estimation and fuel mixing with 1d simulations of the fuel mixing and rotary engine thermodynamic performance. Analytical models and calculations estimate the effective power and the dimensioning of the mixture formation system. Later on there is a special focus on the modelling of a rotary engine with a commercial reciprocating engine simulation tool that needs significant modifications for calculation of rotary engines. For this work, the authors created a new substitute cylinder model for running the special rotary engine thermodynamic process. The simulation contains the optimization of port timing combined with the intake and exhaust pipes. Finally, the mixture formation system has been coupled with the engine process. The results of the simulations and the analytical methods show the effects of separate design and thermodynamic parameters in combination with regenerative gaseous fuel on the volumetric efficiency, residual gas fraction and scavenging fraction. The work makes a fundamental contribution to the use of novel fuels in conjunction with specially designed internal combustion engines.