Evaluation of turbine film cooling holes designed for engine scale additive manufacturing

In recent years, it has become feasible to use additive manufacturing (AM) for gas turbine components, which allows novel turbine cooling designs such as rounded inlet film cooling holes. This thesis investigates the sensitivity of shaped holes designed for engine scale AM to internal roughness features produced during construction. In the study, two versions of a nominally 9-9-3 film cooling hole were evaluated with both “as-designed” and “as-built” configurations. The two 9-9-3 versions are an original rounded inlet hole as well as a rounded inlet and exit hole designed to minimize deformations that commonly occur with AM. Each hole configuration was constructed at engine scale using direct laser metal sintering (DMLS). The surfaces of these “as-built” geometries were characterized through computerized tomography (CT) scans. These scans were then used to build a scaled-up model of adiabatic and matched Biot number models, which were experimentally tested in a low speed wind tunnel to obtain adiabatic and overall cooling effectiveness data. In addition, computational predictions were performed for the rounded inlet, as-designed hole and compared to experimental data