Design, Development and Validation of Additively Manufactured First Stage Turbine Vane for F Class Industrial Gas Turbine

Abstract

Emerging additive manufacturing technology offers many opportunities for improved cooling design in gas turbine components by enabling design of cooling passages and shapes that are not manufacturable with conventional methods. Many combustion components have already taken advantage of these design opportunities however adaptation of this technology in turbine hot gas path components has been slower due to challenges with demanding environment and restriction on material properties obtained from additive manufacturing. This paper represents application of additive manufacturing technology in an F class industrial gas turbine including design, development and validation steps of a 1st stage turbine vane. A systematic design approach was undertaken to examine all aspects of operation and cooling of the component to down-select the appropriate design, material and processing. Detail characterization of multiple relevant material properties such as LCF, fracture toughness and creep was conducted to obtain material data and generate elastic and viscoplastic models for component design. Subsequent microstructural analyses of creep specimen were conducted to evaluate creep mechanism. Cooling design studies and coupon specimen testing were conducted to determine heat transfer and flow characteristics of micro channels used in the airfoil design. Detailed conjugate heat transfer analyses were used to iterate and optimize the cooling design. Once final design requirements were achieved, a number of prototype engine components were manufactured and tested in continuous engine operation for a predetermined duration of more than 6 months. These prototype components were removed from the engine after successful operation for validation purposes. Uniform crystal temperature sensors (UCTS) were used to validate the new cooling design. Destructive microstructural evaluations were performed to determine the impact of in-service operation on additive manufactured material. Details of the design and development steps as well as the results of prototype tests and microstructural evaluations are presented and discussed in this paper. It is demonstrated that with proper considerations of the resulting material properties, adaptation of additive manufacturing technology in turbine components is feasible with a comprehensive development process.

Advanced Gas Turbine Cooling for the Carbon-Neutral Era

“…A first additively manufactured DWC (for a sketch of the principle, see Figure 21a) vane was tested in a large frame gas turbine by Ref. [109]. The design itself and the comparison with the traditionally cast vane and the normal cooling design are shown in Figure 21.…”

“…Currently, additive manufacturing is being used in a series design of low-temperature components [111], and its suitability for high-temperature components is being evaluated [109,112]. The remaining uncertainties for high-temperature components in particular lie with the printing of materials that contain γ'-phases [113], which are traditionally considered non-weldable.…”

“…[116] were manufactured from MAR M-509 because they were used in direct comparison with cast NGVs, which were also made from this material. Others have investigated IN939 [109], which showed that the material parameters of the AM parts differed dramatically from cast ones or those made of IN738. This last material has received some attention, but its use is still at an experimental stage [117,118].…”

“…Moving away from the theoretical considerations into more practical ones, a brief overview of the application of internally cooled AM components in gas turbines is offered. Although the blades would profit most from AM designs (the vanes are already cooled well with impingement cooling), given the concerns about the material properties of AM parts, most work has been done on stationary components [109,116,[147][148][149][150]. In Ref.…”