Experimental and Numerical Study of Turbulent Flow and Heat Transfer in a Wedge-shaped Channel with Guiding Pin Fins for Turbine Blade Trailing Edge Cooling

摘要

Gas turbine blades employ wedge-shaped channels for the trailing edge internal cooling. Detailed experimental and numerical analyses have been done on the heat transfer and turbulent flow structures in a wedge-shaped channel with arrays of streamlined pin fins for the Reynolds number range from 20,000 to 80,000. The study examines two different configurations of the streamlined guiding pin fins in the wedge-shaped channels, which show the potential of flow guiding and heat transfer improvement for the turbine blade trailing edge internal cooling. The experiments indicate that the streamlined shape of the guiding pin fins causes significantly reduced pressure losses compared to the baseline circular pin fin arrays. Depending on two different configurations the guiding pin fin arrays can achieve pressure loss reduction by up to about 37.3% and 8.7%, respectively, while obtaining appreciably higher average heat transfer on the bottom wall by up to about 8.8% and 12.0%, respectively, compared to the baseline circular pin fin arrays. Besides, the conjugate numerical simulations obtain the total Nusselt numbers of the different pin fin array configurations. Depending on two different configurations the guiding pin fin arrays increase the total Nusselt numbers by up to 11.5% and 13.8%, respectively, compared to the baseline circular pin fin arrays. Additionally, the heat transfer enhancement and pressure loss reduction present more significant promotions for the guiding pin fin arrays as the Reynolds number increases. Also, the numerical simulations reveal the detailed flow structures in the wedge-shaped channels with different pin fin configurations and demonstrate the flow guiding mechanism of the guiding pin fin arrays. Due to the flow optimizations by the guiding pin fin arrays in the wedge-shaped channels, the heat transfer and flow distribution uniformities are improved.