Numerical study on hot streak migration characteristics of micro axial turbine

Abstract

The thermal load distribution and aerodynamic performance of turbine are affected by the hot streak (HS) migration characteristics. Especially in micro turbine, hot streak will show different migration characteristics affected by dimensional effect (DE). In this paper, a numerical study was employed on a micro axial turbine (MAT) to investigate the HS migration characteristics. Combining theory with numerical result, the phenomena of ''heat deposition'' and ''heat migration'' in micro turbine are revealed. The results show that: In MAT stator, the hot streak will migrate toward the hub 1.1% blade height for heat deposition, which is not obvious in conventional turbine stator. In MAT rotor, the heat streak will migrate to the blade pressure surface around 30.9% of the passage pitch, which is 4.3% more than that in conventional turbine. In addition, the hot streak transfers very complex due to the effects of the hub secondary flow and the leakage flow, and tends to be stretched into two parts. The study provides a theoretical reference for the aerodynamic and cooling design of MAT.

Keywords

• Micro axial turbine
• Hot streak
• Numerical simulation
• Heat deposition
• Heat migration