Additive Manufacturing of Hot Gas Path Parts and Engine Validation in a Heavy Duty GT

Abstract

Additive manufacturing and in particular Selective Laser Melting (SLM) are manufacturing technologies that can become a game changer for the production of future high performance hot gas path parts. SLM radically changes the design process giving unprecedented freedom of design and enabling a step change in part performance. Benefits are manifold, such as reduced cooling air consumption through more efficient cooling schemes, reduced emissions through better mixing in the combustion process and reduced cost through integrated part design. GE is already making use of SLM for its gas turbine components based on sound experience for new part production and reconditioning. The paper focuses on: a) Generic advantages of rapid manufacturing and design considerations for hot gas path parts b) Qualification of processes and additive manufacturing of engine ready parts c) SLM material considerations and properties validation d) Installation and validation in a heavy duty GT Additive Manufacturing (AM) of hot gas path components differs significantly from known process chains. All elements of this novel manufacturing route had to be established and validated. This starts with the selection of the powder alloy used for the SLM production and the determination of essential static and cyclic material properties. SLM specific design features and built-in functionality allow to simplify part assembly and to shortcut manufacturing steps. In addition, the post-SLM machining steps for engine ready parts will be described. As SLM is a novel manufacturing route, complementary quality tools are required to ensure part integrity. Powerful nondestructive methods, like 3D scanning and X-ray computer tomography have been used for that purpose. GE’s engine validation of SLM made parts in a heavy duty GT was done with selected hot gas path components in a rainbow arrangement including turbine blades with SLM tip caps. Although SLM has major differences to conventional manufacturing the various challenges from design to engine ready parts have been successfully mastered. This has been confirmed after the completion of the test campaign in 2015. All disassembled SLM components were found in excellent condition. Subsequent assessments of the SLM parts including metallurgical investigations have confirmed the good part condition.

Effectiveness Measurements of Additively Manufactured Film Cooling Holes

“…Within that limited body of literature, most papers focus on characterizing the manufacturing process and the resulting material properties; only a few of them focus on the effects AM has on heat transfer performance of gas turbine parts. However, patents describing inventions with AM film cooling [5][6][7][8] and a paper written by Schurb et al [9] clearly show that gas turbine engine manufacturers are exploring the use of AM for actively cooled turbine hardware.…”

Numerical Optimization, Characterization, and Experimental Investigation of Additively Manufactured Communicating Microchannels

“…Effectively taking advantage of the open design space offered by AM requires thinking outside the conventional designs for heat exchangers [34,36]. The current study is unique in that it combines a conventional cooling channel design with an idea derived from transport systems in nature.…”

Analysis of Parameters Influencing Build Accuracy of a SLM Printed Compressor Outlet Guide Vane

“…[8] used the technology to produce a high-pressure nozzle guide vane with complex internal cooling system and conducted a laboratory test to assess its thermal performance as a means of predicting the performance of the cast alternative. Stator heat shields for hot gas path was also designed and printed using the technology, leading to a reduction in part volume, and the applied stock for conventional finish machining, hence, allowing cost and time savings [9]. Can-combustor components and six air blast fuel nozzles were also manufactured using the AM technology in a development program that was looking at advancing the state of art in Unmanned Aerial Vehicle power systems [10].…”