As part of the Clean Sky 2 programme, this EU funded project has allowed Ilmor to introduce some novel processes, materials and ideas to an existing certified diesel aero engine.

The initial aims of reducing mass and increasing cooling performance, to allow the engine to operate at a higher power output for the duration of its life, have been achieved.

The overall mass of the engine has been reduced by 2.6%, mostly by replacing the iron liners with a plasma bore coating. A possible further mass reduction of 1.6% is available through the use of a steel piston and redesigned con-rod.

Finite element analysis has been used to predict that all components will survive for the ‘time between overhaul’ life of the engine, whilst operating at a higher power output than currently required for certification.

Computational analysis was used to assess design changes and verify that the cooling performance of the engine increased, keeping the higher temperatures under control. Mass flow of air through the cylinder head has increased by 5%, and barrel surface area has increased by 39%. Test measurements recorded a drop in temperature in the cylinder head material around the combustion chamber of, on average 19°C.

Other changes like the introduction of the combustion seal and the DLC coating on the stiffer gudgeon pin contribute towards improved robustness of the engine over its lifetime.

As well as being lighter and more robust, the crankcase, cylinder barrels and cylinder heads have been cast using printed cores, which reduced development times. Assembly of these parts has been simplified, and the design also yields a reduced part count. These changes will have a positive economic effect for the engine manufacturer, which in turn could lead to a positive socio-economic benefit.

The hope is that knowledge gained from this investigation can benefit the wider aeronautical community by contributing towards improving the performance and efficiency of the next generation of aero diesel engines.

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This project has received funding from the Clean Sky 2 Joint Undertaking under the European Union’s Horizon 2020 research and innovation programme under grant agreement No 686533