14th European Conference on Turbomachinery Fluid dynamics & Thermodynamics
The high-speed cascade wind tunnel (HGK) of the Bundeswehr University Munich is a well-known test facility in the turbomachinery community. Due to its ability to change two similarity parameters, namely Mach and Reynolds number, independently from each other at engine relevant flow conditions, it is a unique test facility worldwide, whose performance map is very well suited for research on airfoil aerothermodynamics. The facility’s large test section dimensions of up to 500H x 300W mm² enable very detailed experimental performance characterizations on numerous compressor and turbine airfoil generations which finally made it into service. First, it became operational in 1956 at DFL Braunschweig. In 1984, the entire test facility was moved to the Bundeswehr University Munich, where it got operational in 1985 after an overhaul of the main components and a replacement of the pressure vessel by one of significantly bigger volume. Since that time, the test facility has provided very valuable contributions to the field of turbomachinery. Since there is still a high demand on cascade testing under engine relevant test conditions from industry and basic flow research, which, more than ever, seeks for highly efficient airfoils, it was decided to carry out a major revision of the test facility in order to ensure operational reliability and to upgrade the facility for future research requirements, more than 60 years after its first run and thousands of hours of intensive testing. In particular, the main components, i.e. the drivetrain, the compressor, and the main cooler date back to when the test facility got into service in 1956. During the major revision in 2017/2018 these hardware components were replaced by new ones of the latest technology. Details on the new components will be comprehensively outlined in the paper. The new components now feature a higher power level allowing to extend the operating range of the test facility significantly. Parallel to the hardware, a high level of automation was introduced into the facility. Together with a state-of-the-art real-time data acquisition system, the wind tunnel operation and surveillance finally again satisfy the raised demands on stability and measurement accuracy. All features of the test facility and the extended operating range will be described in detail in the paper. The picture of the “new” HGK is rounded by the available portfolio on experimental techniques, both classical probe-based and non-intrusive techniques, which are also emphasized in the paper.