Nambisan J. Experimental Study on Pressure Losses...2017 torrent

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Gas turbine components for cooling purposes including other unique and complex three-dimensional designs could be made explicitly possible through additive manufacturing using SLM technology in contrary to the conventional machining processes. Nevertheless, the surface roughness and subsequently the friction factor governs the pressure drop in these components implicitly, thus, inuencing the secondary air flow system of a gas turbine. Research studies to understand and predict flow behaviours through especially AM parts are still in a budding stage, and thus, in this
scope of thesis, the same has been attempted through experimentation to quantify pressure losses in additively manufactured rectangular ori ces. With the purpose of a brief analogy, a set of aluminium circular samples were also tested which were manufactured by the conventional process of machining. A total of 9 rectangular MA247 samples of different lengths and hydraulic diameters were tested as continuation to the ongoing research at Siemens Industrial Turbomachinery AB and further on to that, 5 Aluminium Alloy- AW-6082 T6 material samples of circular geometry
with varying lengths were tested. The on-going research focuses on the additively manufactured geometries for both rectangular and circular, and hence, the data for circular ori ces were used to draw a comparison with its Aluminium counterpart. Pressure losses here were described using the coecient of discharge and the investigations on roughness were by calculating Darcy frictional factor and Colebrooks equation. Classical theories such as the boundary layer theory, Hagen's power law, Ward-Smith's theory for vena contracta and other works by previous researchers
were used to validate the results. The coefficent of discharge could be deployed to restrict and measure the mass flow in the secondary air systems, whereas the results from the calculated frictional factors could be held to simulate the flow distribution in cooling geometries