Experimental Heat Transfer Investigation in a Multisplitter LP Vane Architecture

This paper reports the external convective heat transfer in an innovative low pressure vane with multisplitter configuration. Three small aerodynamic blades are positioned between each structural vane, providing a novel architecture for ultra-high by-pass ratio aero-engines, with increased LP vane radius and swan-neck diffuser to link the HP turbine. The measurements have been performed in the compression tube test rig of the von Karman Institute, using single layered thin film gauges. Time-averaged and time-resolved heat transfer distributions are presented for the three aerovanes and for the structural blade, at three pressure ratios tested at representative conditions of modern aeroengines, with M_2,is ranging from 0.87 to 1.07 and a Reynolds number of about 10⁶. This facility is specially suited to control the gas-to-wall temperature ratio. Accurate time-averaged heat transfer distributions around the aerovanes are assessed, that allow characterizing the boundary layer status for each position and pressure ratio. The heat transfer distribution around the structural blade is also obtained, depicting clear transition to turbulence, as well as particular flow features on the pressure side, like separation bubbles. Unsteady data analysis reveals the destabilizing effect of the rotor left-running shock on the aerovanes boundary layer, as well as the shift of transition onset for different blade passing events.