Assessment of Binary Pressure Sensitive Paint for Temperature and Heat Transfer Coefficient Measurement of Leading Edge Film Cooling Conference Paper uri icon

abstract

  • Abstract Film cooling is a common technique for protecting the leading edge of gas turbine vanes from the hot combustor exhaust. In the laboratory, film cooling effectiveness distributions are often obtained by measuring the mass transfer of a foreign gas coolant in mainstream air with pressure sensitive paint (PSP), eliminating the inherent conduction errors of steady-state heat transfer experiments and providing highly resolved measurements. However, both the effectiveness and heat transfer coefficient are necessary to calculate the heat flux for a given film cooling configuration and fully quantify the impact on the vane surface temperature. The heat transfer coefficient generally requires a thermal test, which typically uses thermochromic liquid crystal (TLC), infrared (IR), or temperature sensitive paint (TSP) to measure the surface temperature. Alternatively, the additional luminophore in binary pressure sensitive paint (BPSP) can be used to measure the surface temperature. The second luminophore of most BPSPs is sensitive to temperature for use as a reference to correct pressure measurements for adiabatic heating in transonic and supersonic flows, but it can also be used to directly measure the surface temperature. As a proof of concept, this paper uses BinaryFIB PSP from Innovative Scientific Solutions (ISSI) to measure the film cooling effectiveness and heat transfer coefficient on the leading edge of a cylinder, approximating flow on the leading edge of a gas turbine vane. The cylinder has a 7.62-cm diameter with two rows of cooling holes at 15 from the leading edge. Each row contains 10 holes with a 0.475-cm diameter, spaced 4 diameters apart in the spanwise direction and angled 30 from the cylinder axis. The mainstream Reynolds number was 100,000 based on cylinder diameter with a turbulence intensity of 7.1%. The coolant-to-mainstream density ratio was 1.0, and the blowing ratio was 0.8. The film cooling effectiveness was measured in a typical steady-state mass transfer experiment using the pressure signal from the BPSP and nitrogen as coolant. The heat transfer coefficient was measured in a transient heat transfer experiment using the reference signal from the BPSP. The transient calculations assumed 1-D semi-infinite heat transfer. Despite the high uncertainty of the measurement ranging from 24.0% to 71.1%, the results demonstrate the feasibility of the method, identify the best test methodology to minimize conduction errors, and provide a reasonable comparison with previous measurements in the literature. Further BPSP development of the reference luminophore is recommended to improve the sensitivity to temperature and increase the glass transition temperature.

name of conference

  • Volume 8: Fluids Engineering; Heat Transfer and Thermal Engineering

published proceedings

  • Volume 8: Fluids Engineering; Heat Transfer and Thermal Engineering

author list (cited authors)

  • Burdett, T. A., Yeh, M., Wright, L. M., & Han, J.

citation count

  • 0

complete list of authors

  • Burdett, Timothy A||Yeh, Ming-Feng||Wright, Lesley M||Han, Je-Chin

publication date

  • October 2022