Abstract

Fine particulate deposition testing was conducted with an effusion plate film cooling geometry representative of a gas turbine combustor liner. Preheated coolant air with airborne particulate was fed into an effusion plate test fixture located in an electric kiln that establishes the elevated plate temperature, similar to a gas turbine combustor. Experiments were conducted at constant pressure ratio across the effusion plate. Test variables include hole diameter, length/diameter ratio, inclination angle and compound angle. In addition, coolant and plate temperature were varied independently to determine their influence on in-hole deposition. All tests were continued until the effusion holes had blocked to produce a 25% reduction in mass flow rate while maintaining constant pressure ratio. The blockage was found to be more sensitive to flow temperature than to plate temperature over the range studied. Blockage was insensitive to effusion hole diameter from 0.5 to 0.75 mm, but increased dramatically for hole diameter below 0.5mm. Blockage shows a moderate increase with hole length/diameter ratio. Roughly an order of magnitude increase in deposition rate was documented when increasing hole inclination angle from a 30° to 150°. A compound angle of 45° caused a negligible change in blockage, while a compound angle of 90° increased blockage for low inclination angles while decreasing it for high inclination angles. For the flow angle dependency, interpretation is provided by means of CFD simulations of the particulate delivery and initial deposition location prediction using the OSU Deposition Model.

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