Numerical Investigation of Flow and Heat Transfer in Gas Turbine Serpentine Passage Cooling and Comparison With Experimental Data

Abstract

Due to recent advancements made in computational technology, CFD tools are capable of accurately capturing complex physical phenomenon. The proposed novel CFD methodology improves the prediction reliability and capability of Gas Turbine Blade heat transfer and secondary flow behaviour. This paper discusses a robust CFD based methodology to validate the complex gas turbine blade cooling design using detailed 3D flow & conjugate heat transfer analysis. Both primary and secondary flow domains along with blade metal are considered in one single integrated CFD model. This will capture the coupled heat transfer and tip vortices mixing effects and hence accurately predict the secondary cooling flow. The secondary flow path geometry consists of serpentine passages with turbulator features in the flow path to improve the effective heat transfer. Several sensitivity studies were performed using the above model to understand the impact of turbulator fillets, tip hole coating thickness, domain interface and suitably accounted for in the full scale simulation. The numerical simulation results were extensively validated with GE industrial Frame5 gas turbine prototype test thermocouple data and thermal profiles (span-wise) obtained from metallographic images. This novel method gives a thorough understanding of flow-thermal physics involved in serpentine cooling and helps to optimize effective cooling flow usage.