Experimental research on film cooling characteristics of converging-expanding hole rows on turbine blade surface

The film cooling effectiveness distributions of converging-expanding hole rows on the turbine blade model are measured using a steady liquid crystal measurement technique. The influences of Re based on the blade chord length and coolant-gas flux ratio are tested, and comparison is made between the effect of the converging-expanding hole rows and cylindrical hole rows. The results show that the jet trace is converging on the suction side and expanding on the pressure side for both converging-expanding hole rows and cylindrical hole rows owing to the influence of the passage vortex system. However, compared to the cylindrical hole rows, the influence of the passage vortex on the jets of converging-expanding hole rows is weaker, and the film covering area and the film cooling effectiveness of converging-expanding hole rows are much larger on both the suction and pressure sides. The film cooling effectiveness of converging-expanding hole rows increases with the increase of the coolant-gas flux ratio, increasing, and the film cooling performance on the pressure side is better than that on the suction side for both kinds of hole rows because of the concave surface. The influence of Re on cooling effectiveness distribution and the cooling effectiveness value of the converging-expanding hole rows is nearly negligible on both the suction and pressure sides in the range of the current test conditions.