Effect of fuel injection timing variation in a newly designed opposite piston diesel engine for unmanned aerial vehicles

This article plans to present measurements and heat flux analysis of an aircraft compression ignition engine with opposed pistons. The new 100 kW engine is designed for propulsion of unmanned and ultralight aircraft. The engine adopts the developed technology of automotive engines (common rail system, supercharging) and a new arrangement of cylinders with opposed pistons. The author will present the results of energy balance studies of the designed internal combustion engine. Types of heat losses occurring in particular engine systems will be analyzed. The analysis will include results for each type of heat flux (air, fuel, exhaust, cooling, lubrication) as a function of injection time. The engine will be studied in the range of 3600 rpm, the injection time will be varied from 0.49 to 0.86ms. In addition, the energy balance of the tested engine will be presented using Sankey diagrams. During the tests, the efficiency of the engine will be determined. In real conditions, this efficiency will decrease due to the additional mechanical load on the supercharging system (compressor drive), the oil and cooling system (pump drive) and the on-board power generation system (alternator drive). Knowledge of the individual heat losses in the engine systems is essential for proper engine installation and selection of optimal injection timing. Analysis of the distribution of thermal energy generated during the combustion process is important for performance and efficiency.