58820 - A Discussion: Issue Improving the Accuracy of Turbine Blade Heat Transfer Simulation 

   As the turbine inlet gas temperature is continuously increasing, more and more sophisticated cooling techniques are adopted to maintain blade at acceptable temperature. It is critical for cooling design of turbine to predict the heat transfer between solid wall and high temperature gas precisely. Numerical simulations is one of important ways to predict heat transfer around blade, however, there always exits large error compared with experimental results, even opposite conclusion may be drawn. Some numerical investigations try to reduce the error by adjusting turbulence model parameters, but the effect is limited. There have to be extended section at inlet of the first turbine guide vane in simulation, if turbulence characteristic parameters from experiment is directly assigned as inlet boundary,  turbulence will dissipate in the extended section so that turbulence intensity deviates from true one at specific location. Therefore, it is more possible that inaccuracy turbulent boundary is responsible for the error. The current investigations aim to study the issue. Numerical domain of UTRC (United Technologies Research Center) 1.5-stage turbine was established according to literature data. Due to special requirements of transition on grids, strict grid independent tests were conducted. Based on these grids, 3-dimensional flow simulations were performed with  V2F, SST and SST γ-Re_θ. The Stanton number at mid span from simulation results were compared with experiments to verify the reliability of these simulations. And then, related investigations were performed. Results show that the error between simulation and experiment can be eliminated to a certain extent by approach that to make turbulence parameters at measurement station consistent with experiment by adjusting turbulence parameters of inlet boundary. So, it is key for accurate prediction of flow transition and heat transfer to match turbulence characteristic parameters at measurement station in simulation.

Keyword: turbine blade heat transfer, numerical simulatiom, inlet extended section ,turbulence dissipating