This paper presents extensive results of an ongoing study on internal blade cooling concepts. A new test rig has been designed, built and commissioned, allowing fast comparison of different cooling schemes as well as surface temperature measurements for different cooling concepts. By scaling the test specimen, full aerothermal similarity was achieved at high measurement accuracy and resolution. Surface temperature (and thus total cooling effectiveness) is measured using high resolution, high dynamic range infrared thermography with an improved data evaluation method.
Results for a conventional multi-pass cooling design are presented as a baseline case. Several new internal cooling concepts are then assessed for their relative cooling performance to the conventional design as well as their absolute cooling effectiveness. Those designs include various internal swirl concepts (cyclone cooling). The results show that great care has to be taken when designing advanced internal cooling concepts with complex flow structures, since the effects of internal crossflow, internal pressure loss, internal heat transfer coefficient, and film cooling effectiveness strongly interact with each other and the hot gas flow and hence affect the resulting total cooling effectiveness.