Cooling hole geometry and turbulence effects on the early suction side surface of a turbine vane

Most film cooling research is conducted on simplified experiments such as low speed flat plates. The research is used to derive empirical correlations, later applied during the design phase of film cooling systems. This thesis looks at small design changes in the film cooling geometry on the early suction side at the closest practical aerodynamic boundary conditions, i.e. density ratio, turbulence level, Mach and Reynolds numbers. Two rigs have been designed and built for this work: LE-Sim, leading edge simulator; and FPlate, flat plate. The former is a 1:1 scale annular sector cascade of the Mitsubishi F-701 first stage nozzle guide vane. The latter is a flat plate arrangement matching the Reynolds number achieved by the LE-Sim on the early suction side. In this thesis, six cooling designs are tested on the LE-Sim and the impact of the turbulence is analysed on both rigs. The two arrangements provided similar ranking on the averaged film cooling effectiveness for similar momentum flux ratios at medium and high turbulence (𝑇𝑢 ≥ 4%). The impact of the turbulence is related to both the upstream leading edge holes and the rate of diffusion imposed to the coolant from the different geometries. The fan-shaped geometries outperformed the double row cylindrical geometries with higher averaged film cooling effectiveness; but the fan-shaped geometries showed significant hole-to-hole variability. This behaviour was found at all turbulence intensities and most of the momentum flux ratios analysed. Increased turbulence and/or momentum flux ratios exacerbated the variability. In some cases, the cooling holes would not provide any protection to the surface because the jets would coalesce, thus giving the possibility for localised burning. Different causes, such as manufacturing defects and turbulence, have been considered to be the cause of the hole-to-hole variability. However, ultimately it is thought that both the internal feeding and the increased diffusion of the fan-shaped geometries could be more important.

Name dc:type.qualificationname

Doctor of Philosophy (PhD)

Level dc:type.qualificationlevel

Doctoral

Grantor dc:publisher.institution

University of Cambridge

Year dc:date.issued

2016

Author dc:creator

• D'Ammaro, Antonio D

Advisor dc:contributor.advisor

• Atkins, Nicholas

• Cooling hole geometry
• turbulence

Licence

• https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/6436725f-fa17-43f7-8f2d-0ee8167ffda5/download
• http://purl.org/NET/rdflicense/allrightsreserved/

DOI dc:identifier.doi

https://doi.org/10.17863/CAM.114399

OAI identifier oai:identifier

oai:www.repository.cam.ac.uk:1810/377655