Experimental Acquisition Of An Endwall Heat Distribution In A Linear Turbine Cascade

The focus of this research is the experimental acquisition of endwall heat transfer distributions for an aft loaded vane with a large leading edge. This study will investigate endwall heat transfer distributions over five inlet turbulence levels ranging from intensities of 0.7% through very high turbulence levels as high as 17.4%. The investigation will be conducted at three varying Reynolds numbers based on true chord length and exit conditions ranging from 500,000 to 2000,000. The infrared thermography technique will be applied to the acquisition of the endwall heat transfer data due to the full surface image which can be developed from the acquired thermographs. An in situ calibration technique will be used to enhance the measurement accuracy. The experiment was conducted in a linear cascade test section, consisting of four turbine vanes with upper and lower bleed flows. Linear Cascade can reflect most of the flow characteristics in real gas turbine nozzles. This experiment exhibits some other advantages, such as geometric simplicity, simple adjustment, and large blade sections. This study will emphasize the effect of turbulence and Reynolds number on endwall heat transfer to ease cooling systems development for both turbine vanes and endwalls. Two different measurements were taken, one with the endwall heated and the other with the endwall heat turned off to ground the in situ calibration. The surface heat transfer was taken at three varying based on exit Reynolds number and was exhibited in terms of Stanton number based on exit conditions.It is expected that the low turbulence heat transfer contours exhibit strong evidence of the impact of secondary flows on heat transfer patterns as influenced by the vane\u27s leading edge region and the pressure surface to the suction surface pressure gradient. Heat transfer contours at higher turbulence levels are expected to show weaker secondary flow evidence due to the enhanced turbulent mixing and flow instability. However, the higher turbulence levels are expected to generate higher levels of heat transfer near the leading edge and downstream from the wake, and in the passage due to earlier transition. These measurements are expected to provide benchmark quality data to ground the development of high-fidelity predictive tools