Smart sensors for greener helicopters
The Sustainable and Green Engine (SAGE) 5 concept is a planned Integrated Technology Demonstrator (ITD) to develop eco-friendly and silent turboshaft engines for helicopters. This is in line with the Clean Sky initiative. Reducing emissions of toxic gases is largely related to increasing fuel conversion efficiency and thus lowering fuel consumption. Power transmission optimisation can thus increase efficiency and reduce noise. In order to optimise fuel consumption and engine function, it is necessary to modulate shaft speed and the temperature and pressure of air, fuel and oil. EU-funded scientists investigated the potential of smart monitoring technology to facilitate reductions in emissions and noise in the context of the project 'Active pressure, position and temperature sensors for turboshaft engines' (ACTIPPTSENS) . The original focus was on two types of emerging sensor technologies: contactless torque sensors (CTSs) to measure torque and rotation speed, and piezoelectric microelectromechanical system (MEMS) sensors. For the latter, the plan was to incorporate a piezoelectric transducer (PZT) pressure sensor based on electrospun PZT nanofibres with a thermocouple to measure operating temperature. The team modified a CTS, developed and patented by a partner for cars, to be suitable for helicopter use. It was manufactured and tested, demonstrating better sensing performance and durability against ageing. In addition, it is capable of measuring static behaviour and can be plugged onto the shaft rather than being inserted in a cut. Although the piezoelectric nanofibre mesh with the desired microstructure was successfully fabricated, technical difficulties with further process steps prohibited further development of the PZT-MEMS sensor. Scientists thus used a commercial PZT solution instead. Further development and optimisation of the smart monitoring technology will have important implications for the production of greener and quieter helicopters in the near future.
