Design and Characterization of Additively Manufactured NGVs Operated in a Small Industrial Gas Turbine

The use of additive manufacturing (AM), for example Selective Laser Melting (SLM), is poised to spark a revolution in the way high-temperature components for gas turbines are designed, but a number of grave uncertainties remain. These lie mainly with the materials sciences, but some questions with regard to manufacturing and operating SLM-parts as hot gas path components and the demands on the tolerances of the cooling features associated therewith remain as well. In order to quantify the impact of these uncertainties, Nozzle Guide Vanes (NGVs) with a geometry that would normally be investment-cast were produced with SLM. A back-to-back comparison of vanes from the two manufacturing processes was performed. The design of the SLM-vanes will be described and the SLM-manufacturing process of the NGVs will be touched upon, especially the use of MAR M-509, which is seldom used for SLM. In addition, characterization of the NGVs with 3D-scans of the outer geometry and the pin-fin matrix shall be discussed. The NGVs were operated for approximately 70 hours at relevant load conditions in a highly-instrumented test engine on a test bed at the Oberhausen plant of MAN. The temperatures of the AM and investment-cast vanes were measured using Thermal History Paints (THPs); a comparison between these different kinds of parts will be drawn.