Cooling System for 0.1 kN Thrust Micro-Engines: Concept Design Using Additive Manufacturing

Abstract

This project is the outcome of the 2015/2016 Aerospace Outreach Propulsion Program (APOP) and is aimed to add an innovative cooling system to a small turbojet engine of 0.1 kN of thrust. The interesting and innovative aspect of this project is the application and adaption of conventional cooling system solutions to such a small single-stage turbine (11mm of blade height), employed on the JetCat P90-Rxi. The ultimate goal is to increase the maximum temperature of the engine cycle by 150 K, in order to get more thrust. To avoid the failure of the engine due to the higher temperatures, an internal cooling system is implemented to cool down both the stator and rotor of the turbine. The stator blades are provided with internal channels and trailing edge slots to maintain the temperatures below the Inconel 718 thermal limit, while a pattern of bleed holes on the shroud combined with an annular slot at the hub supply cooling to the rotor blades. The rotor blade surface is covered with an innovative thermal barrier coating which should guarantee a sufficient temperature drop. The original stator and rotor components were modified, while the overall structure of the engine was maintained. The new parts were first 3D printed in ABS to verify the matings and, eventually, 3D printed in stainless steel 316L. The final step was the 3D printing in Inconel 718.