15th European Conference on Turbomachinery Fluid dynamics & Thermodynamics

Paper ID:


Main Topic:

Heat Transfer & Cooling


Benjamin Brimacombe  - University of Bath, United Kingdom
James Scobie - University of Bath, United Kingdom
Joeseph Flynn - University of Bath, United Kingdom
Carl Sangan - University of Bath, United Kingdom
Oliver Pountney - University of Bath, United Kingdom


Film cooling within turbomachinery promises to benefit greatly from recent developments in additive manufacturing, utilising the control of material permeability to provide an evenly distributed coolant film. Known as transpiration cooling, this cooling technique improves on discrete-hole cooling by reducing lateral temperature variation and gradients within the cooled surface. In addition to permeable structures, additive manufacture allows control of the internal structure of the permeable surface, enabling the use of gyroids. Gyroids are self-supporting structures that provide a large area for heat exchange, as well as the ability to impart swirl to the coolant flow as it is introduced to the mainstream. This study aims to apply these qualities to demonstrate the capability of gyroids to provide cooling effectiveness improvements for transpiration cooling, compared to discrete-hole film cooling. The experimental investigation will determine the applicability of porous theory to determine pressure drops across gyroidal structures, before investigating the effect of volume fraction on film cooling effectiveness. Three repeats of four test pieces will be manufactured, with volume fractions of 20, 30, 40 and 50%. A bespoke test facility has been constructed to collect engine-representative film cooling data at ambient conditions. High resolution Infrared Thermography (IRT) will be used to collect quantitative values of the steady state surface temperature for each test piece. The experimental work will be supported by the development of novel additive manufacturing techniques, validated through Computerized Tomography (CT) scans. It is predicted lower volume fractions will result in higher pressure drops, introducing higher velocity flow to penetrate further into the mainstream. It is predicted this will produce a thicker thermal barrier and so improved cooling performance. The findings hope to highlight the potential utility of additively manufactured gyroid structures to distribute a coolant evenly over a film cooled surface, using manufacturing techniques that could be implemented in turbine blade design.

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