Infrared Temperature Measurements of the Blade Tip for a Turbine Operating at Corrected Engine Conditions

A high-speed infrared camera is used to measure the temperature of blade tips in a cooled high-pressure turbine operating at corrected engine conditions in The Ohio State University short duration Turbine Test Facility. These experiments create a challenging problem for infrared imaging since the rotor turns at over 13,000 rpm with tip speeds on the order of 300 m/s, and the surface temperature of the airfoils is on the order of 350 K. This means that the camera needs to capture a low-intensity signal in a very short time period. This article reviews the design and operation of a measurement procedure to accomplish this difficult task along with the postprocessing steps necessary to extract useful data. Raw infrared images are processed by deblurring the images using a nonblind Wiener filter and mapping the two-dimensional data onto the three-dimensional blade. This article also describes experiments covering a range of cooling flowrates and main flow temperatures. In addition, several tests with no main flow and only cooling flow were performed at lower speeds to reduce motion blur and enable the separation of internal and external heat transfer information. Results show that the infrared data are consistent and can provide quantitative comparisons of cooling performance even at the high rotation speed. This article presents the lessons learned for high-speed infrared measurement along with the representative data to illustrate the repeatability and capability of the measurement scheme as well as suggested improvements to guide further development.