Performance Prediction of a Two-Stroke Aviation S.I. Engine by Means 0D/1D Thermo-Fluid Dynamic Simulation Code

Two-stroke engines represent an attractive solution for aviation industry applications (UAV, VTOL Aircraft, Ultralight Aircraft) thanks to their compact size, high power-to-weight ratio, reduced moving parts and possibility to operate with different fuels. This work presents a 0D/1D methodology for the simulation of gas exchange, combustion and unsteady flow of a two-stroke aviation engine. Its scavenging and combustion processes, its unsteady flow inside the induction and exhaust systems, are investigated by means of a 0D/1D modelling approach. This work has been motivated by the need to assess the accuracies of such models with respect to the prediction of engine performances. For this purpose, the thermo-fluid dynamic code GASDYN have been applied and enhanced. The proposed 0D model has then been embedded into a 1D fluid-dynamic code for the simulation of the whole engine systems. In order to characterize the baseline configuration, provided of tangential ports which realize a loop-scavenging process, computed results are compared with the available experimental data of engine performances of a conventional two-stroke S.I. ignition engine for aviation industry applications. Validation was carried out in operating conditions representative of UAV operation at different speeds and at full load. Final goal of the activity is to change the exhaust system geometry in order to increase the maximum power of the same engine architecture. Satisfactory results were achieved demonstrating that the proposed approach could be applied to design and optimize two-stroke engines with rather good degree of accuracy and reduced computational costs.