NUMERICAL ANALYSIS OF AIR/MIST COOLING IN A TRAPEZOIDAL INTERNAL COOLING PASSAGE WITH PARTITION WALL AND PIN FINS

The effects of air/mist mixture coolant onflow and heat transfer performance in a trapezoidal internal cooling passage of a turbine blade trailing edge with partition wall and pin fins were numerically investigated. The simulations show that, for air coolant, zigzag partition wall constructs periodic variable cross-section channel along the streamwise which can greatly strengthen the disturbance lead to significant increase of heat transfer accompany with higher pressure penalty, whereas pin fins provide higher turbulence and extended area which can improve the heat transfer performance with relatively small increase of flow resistance. On the basis of enhanced structures of partition wall and pin fins, air/mist mixture coolant (with 1%-10% mass fraction of mist) achieves higher heat transfer or a 28%-40% of overall performance enhancement compared to the air coolant. For improved structure, different mass fraction of water mist can save inlet coolant air at varying degrees. The addition of a small quantity of mass fraction of water mist can save a certain amount of air coolant because of the zigzag partition wall and pin fins. Therefore, this work proposes a promising approach for efficient cooling of gas turbine blade using air/mist mixture coolant and structured internal cooling passages.