In this work, three dimensional numerical studies of the aerodynamics in laminar subsonic cascades at relatively low Reynolds numbers (Re < 2500) are presented. The stator and rotor blade designs are those for a MEMS-based Rankine microturbine power-plant-on-a-chip with 100 micron chord blades. Blade passage calculations in 2D and 3D were done for different Reynolds numbers, four different tip clearances (0%, 5%, 10% and 20%) and four incidences (0°, 5°, 10° and 15°) to determine the flow patterns and compute losses. These conditions are applied to a blade passage without rotation (stator) and with rotation (rotor), both for a stationary and moving outer casing. The 3D blade passage (without tip clearance) indicates the presence of two large symmetric vortices due to the interaction between flow curvature and hub/casing boundary layers. With tip clearance, a secondary vortex appears due to tip flow. This so-called tip vortex becomes dominant in the case of tip clearance above 10%. Relative wall motion also impacts the 3D flow patterns due to the important tangential drag at these low Reynolds numbers. Two dimensional calculations characterize well the flow at the mid-height plane, but are not sufficient for loss predictions due to the omission of the 3D flow structures. The 3D total losses increase dramatically for Re<500, which is similar to 2D studies. This suggests an operating Reynolds number greater than this to obtain efficiency levels necessary to operate a heat engine. The losses also increased monotonically with increasing tip clearance and incidence.
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ASME 2011 Turbo Expo: Turbine Technical Conference and Exposition
June 6–10, 2011
Vancouver, British Columbia, Canada
Conference Sponsors:
- International Gas Turbine Institute
ISBN:
978-0-7918-5467-9
PROCEEDINGS PAPER
Computational Investigation of the Three-Dimensional Flow Structure and Losses in a Low Reynolds Number Microturbine
M. Omri,
M. Omri
Universite´ de Sherbrooke, Sherbrooke, QC, Canada
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L. G. Fre´chette
L. G. Fre´chette
Universite´ de Sherbrooke, Sherbrooke, QC, Canada
Search for other works by this author on:
M. Omri
Universite´ de Sherbrooke, Sherbrooke, QC, Canada
L. G. Fre´chette
Universite´ de Sherbrooke, Sherbrooke, QC, Canada
Paper No:
GT2011-46587, pp. 2179-2187; 9 pages
Published Online:
May 3, 2012
Citation
Omri, M, & Fre´chette, LG. "Computational Investigation of the Three-Dimensional Flow Structure and Losses in a Low Reynolds Number Microturbine." Proceedings of the ASME 2011 Turbo Expo: Turbine Technical Conference and Exposition. Volume 7: Turbomachinery, Parts A, B, and C. Vancouver, British Columbia, Canada. June 6–10, 2011. pp. 2179-2187. ASME. https://doi.org/10.1115/GT2011-46587
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