Pressure-sensitive paint measurement technique development for turbomachinery application

Abstract

Pressure-sensitive paint measurement on a transonic compressor rotor required the prior development of phase-locked cumulative imaging using a disk- rotor driven by a high-speed Hamilton-Standard turbine as a developmental test- bed. The turbine was installed in a protective housing in the Gas Dynamics Laboratory and connected to an 8000 cu ft, 300 psi air supply. An hydraulic pump provided bearing lubrication. A once per revolution trigger signal was produced from a light-emitting diode and PIN photodiode pair. The imaging system consisted of an intensified CCD video camera externally triggered by the 1/rev signal via a waveform shaping circuit designed for the present application. Images were captured at camera gate speeds calculated to eliminate pixel blur and image integration times were varied to optimize image intensity and spatial resolution. Structural and modal analyses of the disk-rotor were conducted and a simplified numerical model of the flow was computed. Ratioed, colored images were produced for wheel speeds to 20,000 RPM. The effect of the radially varying stagnation temperature was evident, underscoring the importance of quantifying and accounting for the PSP temperature sensitivity so that quantitative pressure data may be obtained. Recommendations for a follow-on program are reported