Effects of Heat Transfer on Laminar-to-Turbulent Transition over a Compressor Blade Operating at Low Reynolds Number

To control the transition process in a laminar separation bubble (LSB) over an ultra-high load compressor blade at a Re of 1.5×10⁵, the effects of wall heat transfer were considered and numerically investigated by large eddy simulations (LES). Compared with the adiabatic wall condition, the local kinematic viscosity of airflow was reduced by wall cooling; thus the effects of turbulent dissipation on the growth of fluctuations were weakened. As such, the transition occurred much earlier, and the size of LSB became smaller. On the cooled surface, the spanwise vortices deformed much more rapidly and the size of hairpin vortex structures was decreased. Furthermore, the rolling-up of 3D hairpin vortices and the ejection and sweeping process very close to the blade surface was weakened. Correspondingly, the aerodynamic losses of the compressor blade were reduced by 18.2% and 38.4% for the two cooled wall conditions. The results demonstrated the feasibility of wall cooling in controlling the transition within an LSB and reducing the aerodynamic loss of an ultra-highly loaded compressor blade.