In English

Unsteady 3D CFD analysis of a film-cooled 11⁄2 stage turbine

Jethro Nagawkar
Göteborg : Chalmers tekniska högskola, 2016. Diploma work - Department of Applied Mechanics, Chalmers University of Technology, Göteborg, Sweden, ISSN 1652-8557; 2016:36, 2016.
[Examensarbete på avancerad nivå]

Rising fuel costs and increasing global warming related issues have pushed jet engine manufacturers to increase the efficiency of their engines. One way of doing this is to increase the turbine inlet temperatures. This increases the specific work output of the turbine for a constant pressure drop across it, increasing its thermal efficiency. All the components located downstream of the turbine inlet are however subjected to increased material fatigue due to such high temperatures. This reduces the component life significantly and can also lead to severe engine damage. To reduce the effective surface temperatures, these parts need to be cooled both internally and externally. In this thesis, how film cooling on the nozzle guide vanes (NGVs) of a 1½ stage turbine affects the downstream intermediate pressure (IP) vane has been studied. Point sources available in CFX have been used to model the flow through the cooling holes of the NGVs. The main focus is not to study film cooling on the NGVs, but to study how it affects the IP vane. The function of this vane is to guide the flow from the exit of the high pressure turbine to the IP rotor for further power extraction. The flow in the IP vane is extremely complex. It is affected heavily by the upstream non-uniformities such as tip leakage flows, cold streaks of the coolant, wakes from the blades as well as swirl and hot streaks from the combustion chamber. Four different modeling approaches were studied; no film cooling steady and unsteady as well as film cooled steady and unsteady. The aerodynamic and heat transfer results from these simulations are compared to look for differences arising due to film cooling as well as unsteadiness in the flow to suggest guidelines for IP vane heat transfer analysis. The aerodynamic data is verified with experimental work done at the Oxford Turbine Research Facility (OTRF) by comparing the pressures at three different spans of the IP vane. The pressures at different hub and casing stations in the turbine have also been validated with these experiments.

Nyckelord: Turbine inlet temperature, CFX, NGV, IP, Aerodynamic, Heat transfer, OTRF, Pressure, Film cooling.

Publikationen registrerades 2016-09-05. Den ändrades senast 2016-09-05

CPL ID: 241303

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