Variability in additively manufactured turbine cooling features

Abstract

Additive manufacturing (AM) allows for the rapid fabrication of complex components relative to conventional fabrication methods aiding in the development and testing of advanced turbine cooling methods. The repeatability of printed geometric features in the same part is required to maintain part quality, flow, and heat transfer. It is widely understood as to the impact that the additional roughness of AM provides with regards to part quality, but part variability also leads to differences in performance either locally in considering a single airfoil or globally when considering an entire stage. Previous studies have shown the importance of certain process parameters, build directions, and feature sizes on the part quality when printing a part using AM. As processes have continued to evolve, other artifacts of AM have arisen such as the location on the build plate. This article highlights the progress that has been made on printing commonly used cooling features by either considering simple straight coupons or a curved vane leading edge. Also discussed is the variability that exists and the resulting convective heat transfer and pressure losses. Results indicate that the variation of roughness between components and the part-to-part variations increased the further the component was from the laser source on the build plate. Similarly, the variation and levels in the pressure loss and heat transfer of the cooling channels also increased when samples were placed further from the laser source on the build plate.