Date of Award


Document Type


Degree Name

Master of Science in Aeronautical Engineering


Department of Aeronautics and Astronautics

First Advisor

Paul I. King, PhD


A flow visualization study was conducted on a model of a film-cooled turbine blade leading edge in a closed-loop water channel at ReD = 30k. The model consisted of an 8.89 cm diameter half-cylinder with flat afterbody joined at the ninety degree point. A single radial coolant hole (dc / D = 0.054) drilled 21.5° from the stagnation line, angled 20° to the surface and 90° to the flow direction generated a coolant jet transverse to the freestream. Water channel testing assessed the hydrodynamic effects of 16 passive flow control features, to include a variety of dimples upstream and downstream of the coolant hole and transverse trenches milled directly over the coolant hole. Compared to an unmodified coolant hole, a single row of small cylindrical or spherical dimples (d / dc = 0.79, h / d = 0.2) upstream of the coolant hole steadies the coolant jet at blowing ratios up to M = 0.75. Medium (d / dc = 1.59, h / d = 0.2) and large (d / dc = 2.38, h / d = 0.2) spherical dimples downstream of the coolant hole also have a calming effect on the coolant jet up to M = 0.75. None of the dimple geometries studied affect the coolant jet at M ≥ 0.75. A single-depth, square-edged transverse trench (w / dc = 1, h / w = 0.5) spreads the coolant, increasing spanwise coverage of a single coolant hole more than two times. This trench suffers from coolant blow-out above M = 0.50, but a deeper, tapered-depth trench (w / dc = 1, h / w = 1 at coolant hole tapered to h / w = 0.5 at end) provides very effective film cooling at blowing ratios above M = 0.50. It spreads the coolant in the spanwise direction, prevents coolant jet liftoff, and was the only geometry studied that holds the coolant tighter to the surface than an unmodified coolant hole.

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