The paper investigates the transport of sand particles in the two-pass internal cooling duct of a turbine blade under rotation. The size range is representative of Fine Arizona Road Test Dust from Powder Technology Inc., corresponding to 50% of injected particles being less than 4 microns in diameter, with 90% being less than 50 microns, The geometry consists of a U-bend with 17 ribs in each pass. The ribs are staggered with an e/Dh = 0.1 and a P/e = 10. LES simulation is used with a Reynolds number, Re = 100,000, a Buoyancy parameter, Bo = 0.5, and a rotation number, Ro = 0.2. Deposition and impingement patterns are investigated for three different wall temperatures, 950, 1000, and 1050°C under rotating and stationary conditions. In the first pass, rotation results in much higher levels of impingement and deposition along the trailing wall in comparison to the leading wall and the stationary duct leading and trailing walls. This is due to the action of Coriolis forces which push the particles towards the trailing wall on entry into the rotating duct resulting is a high level of interaction with the trailing duct surface and ribs. Roughly 0.5% of the impacting particles deposit. As a result of this about 84% of the particles deposit in the first pass compared to only 27% in the stationary duct. It is found that temperature effects in the range of wall temperatures from 950–1050°C had no significant effect on deposition. This is because the particle temperatures remained below 900°C, much below the softening temperature of 1120 °C, to have any significant impact on the deposition dynamics. Thus most of the deposits are theorized to be caused by multiple collisions which eventually lead to deposition.
Sand Transport and Deposition in Rotating Two-Passed Ribbed Duct With Coriolis and Centrifugal Buoyancy Forces at Re=100,000
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Dowd, C, Tafti, D, & Yu, K. "Sand Transport and Deposition in Rotating Two-Passed Ribbed Duct With Coriolis and Centrifugal Buoyancy Forces at Re=100,000." Proceedings of the ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition. Volume 2D: Turbomachinery. Charlotte, North Carolina, USA. June 26–30, 2017. V02DT48A002. ASME. https://doi.org/10.1115/GT2017-63167
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