Energy self-sufficient actuated system for aircraft engine ventilation

Shape Memory Alloys are found in a variety of space applications such as satellites, but almost no SMA systems have made it into commercial airplanes so far, even though the technical benefits are similar. In this work, we present our results on the development of a thermal management system for aircraft engines based on SMA.

A suitable thermal management of aircraft engines leads to an efficient working performance and the protection against overheating. By means of scoop intakes situated centrally on the upper cowl of the engine housing, the heat transfer between engine and environment occurs by dint of natural convection. Traditionally, the intakes are continuously open so that the heat transfer and thus the ventilation is permanently permitted. Nevertheless, the traditional assemblies present two drawbacks: Firstly, the aerodynamic drag is consequently increased and hence additional fairings with surfaces flushed with the support plate are mandatory to reduce their contribution to the drag. Secondly, the ventilation is only required temporarily above a critical temperature that is usually reached after landing.

To overcome these issues, an SMA-based actuator system has been engineered and tested under laboratory conditions. A tailor-made shape memory alloy and a manufacturing route were developed to meet the requirements and conditions during operation, such as high temperatures and small hysteresis. Moreover, an energy self-sufficient actuator system was designed to open and close the intake according to the surrounding temperature. Hence, no additional sensors or electrical wires were demanded in the implementation.