Assessment of Steady State PSP, TSP, and IR Measurement Techniques for Flat Plate Film Cooling

Abstract

Several steady state measurement techniques are used to measure the film cooling effectiveness on a flat plate. Pressure sensitive paint (PSP), temperature sensitive paint (TSP), and infrared (IR) thermography are used to measure the film cooling effectiveness. To compare these measurement techniques, a single row of cylindrical holes, with a compound angle, are used. Seven holes (D = 4 mm) are equally spaced 12 mm apart, and the hole length-to-diameter ratio is 9.92. The axial angle (θ) of the holes is 30°, and the compound angle (β) is 45°. In addition to evaluating the various measurement techniques the effect of the coolant blowing ratio is considered; effectiveness measurements are taken for blowing ratios, M, of 0.4, 0.6, 1.2, and 1.8. The effect of mainstream turbulence intensity is considered with the addition of a turbulence grid to the low speed wind tunnel. Of the three steady state measurement techniques considered in this study, PSP demonstrates the most promise for the measurement of the film cooling effectiveness. Because PSP is a mass transfer technique, film effectiveness measurements can be readily obtained near the film cooling holes. Although the heat transfer techniques of TSP and IR thermography are more desirable than traditional thermocouples or liquid crystal thermography, the applicability of measurements near the holes is questionable due to conduction problems associated with steady state heat transfer techniques.