There is a need across the Department of Defense for power plants that yield a reduced environmental impact. In addition, micro-turbine engines, which have both air and ground power applications, are in growing demand. Objectives of the project were to demonstrate the advantages of a newly developed low cost additively manufactured (AM) micro-turbine engine as compared to a similar sized traditionally designed engine. Environmental advantages, related to manufacturing energy consumption and emissions, can be realized while also demonstrating engine efficiency advantages.

The Air Force Life Cycle Management Center Product Support Engineering Division and University of Dayton Research Institute Sustainment Technologies Transition Division team utilized a commercially available EOS M290 AM machine to build a newly designed micro-turbine, employing a powder bed fusion, direct metal laser melting (DMLM) technology that uses lasers to melt ultra-thin layers of metal powder to build a three-dimensional part. DMLM makes possible an iterative design-driven process with significant manufacturing and engine operational improvements. AM technologies offer the capability to rapidly prototype and manufacture the micro-turbine with the following expected benefits: manufacturing cost effectiveness; reduced carbon footprint through less CO₂ emissions during the production process; improved efficiency via optimized engine geometry made possible by the AM process.

Improvements in engine efficiency were identified via use of computational fluid dynamics (CFD) modeling and simulation to determine optimized engine geometry that is also well suited for the AM process. Optimizations of the engine compressor, combustor, and turbine stages were performed. The performance of each stage was demonstrated via printing and testing of the AM engine. The AM engine was successfully tested at its idle condition and up to roughly 50% of its anticipated max speed. The engines performance at these conditions was shown to correlate well to values predicted by the CFD work previously mentioned. Testing at these conditions has also been shown to be stable and the engine’s startup procedure is repeatable. Manufacturing cost benefits were demonstrated through use of cost benefit analysis tools and comparison to costs of similar commercially available engines. Likewise, environmental advantages related to the manufacturing of the AM engine were demonstrated via environmental studies conducted on the AM process and comparison to traditional engine manufacturing methods.

Higher speed testing and full performance mapping of the engine has not yet been completed due to delays caused by complications with manufacturing of the engine test articles and maintenance of the mobile engine test stand. There is still much to be learned regarding the performance of this AM micro-turbine engine and additional testing is needed.

DISTRIBUTION STATEMENT A: Approved for Public Release; AFLCMC-2020-0073 24 March 2020