Grant: Alliance Grants

The most promising path to decarbonize commercial flights are synthetic fuels and carbon offsets. In both cases, the fuel costs will increase significantly, making improvement in engine efficiency paramount in reaching an economically viable solution. Large gas turbines have reached impressive efficiency levels, but small gas turbines remain relatively inefficient due to limited combustion temperatures combined to high viscous and tip losses. In order to achieve radical reduction in fuel consumptions, manufacturers are forced to revisit alternative engine configurations with a new perspective. Prime candidates for cleaner propulsion are the non-reciprocating combustion engines that combine high efficiencies of volumetric engines while being well-known for their high power density. Unfortunately, these engines are also well-known for their oil consumption that needs to be reduced before they are used for aerospace applications in order to meet customer perceptions, weight and forthcoming emission regulations. The first targets are to address leakage through the face-sealing Oil Control Rings (OCRs) and injected oil spilling away from the gas seals as they can be drastically reduced from current values without a significant impact on engine durability. This proposed project aims at reducing oil consumption through the development of improved OCRs and injection strategy. The team will: (1) measure the impedance of the OCRs and their embedded O-ring to update the model and guide the design of new OCRs, (2) use the current experimental setup that measures the effect of secondary motion on oil consumption to test the performance of the new OCR designs, and (3) build a new rig to observe oil injection to the gas seals and test new strategies for directing oil to the running surfaces. The results will reduce direct hydrocarbon emissions, contribute to enabling engines that will reduce CO2 emissions and strengthen Canadian industry leadership in advanced propulsion.