Design and Fabrication of a Thermally Optimized Gas Turbine Nozzle

Abstract The goal of this study was to develop a highly cooled, turbine nozzle designed for use in extremely high temperatures exhausting from a hydrogen-fueled combustor. This design was based on the nozzle being manufactured using metal additive manufacturing techniques. The increasing fidelity of additive manufacturing enables the fabrication of complex geometries, allowing the implementation of more optimized cooling schemes. The present study details the design of a symmetric airfoil, or strut, mimicking that of a turbine vane. In particular, the final design featured novel film cooling holes recently developed in our laboratory, and an array of impinging jets and a lattice structure of pin fins were the mechanisms responsible for internal cooling. Reynolds-averaged Navier–Stokes (RANS) computational simulations were used to determine coolant flow within the airfoil and exhausting film cooling holes for the final strut design. For validation of the computational predictions, an experimental model of the final design was fabricated and tested in a low-speed wind tunnel facility. Results will be shown comparing computational predictions and experimental measurements. In addition, the strut was simulated under engine realistic temperatures, 1750K, and approach velocities equivalent to a mainstream Mach number of Ma∞=0.039. The design was found to successfully keep the wall temperature sufficiently below the melting temperature of Inconel 718. These conditions match those of a hydrogen combustor facility at Southwest Research Institute, which will be used in future work to validate the results of the present study.