Identifier

etd-11142007-202701

Degree

Doctor of Philosophy (PhD)

Department

Mechanical Engineering

Document Type

Dissertation

Abstract

An improved two equation turbulence model has been developed in this dissertation to better predict the complex film cooling flow field that is formed from the interaction of a coolant jet and a crossflow over a modeled turbine blade surface. Film cooling of turbine blades is commonly employed to effectively protect turbine blades from thermal failure and thereby to allow higher inlet temperatures in order to increase the efficiency of gas turbine engines. Film cooling involves the injection of rows of coolant jets from slots on the surface of a turbine blade which is then bent over by the crossflow gases to form a protective coolant film on the blade surface. The highly complex flow field arising from the impact of the coolant jet on the crossflow is the focus of the numerical investigation undertaken in this study. A systematic, step by step approach has been adopted in this work to analyze the flow physics of the film cooling problem and to get an accurate representation of the flow field through numerical simulations that employ Reynolds Averaged Navier Stokes (RANS) turbulence models. Towards this end, numerical predictions have been obtained for the flow problem at hand by employing available models in order to assess the present modeling capabilities. A wide range of turbulence models have been used and their deficiencies have been underscored in order to isolate avenues of model development. The exhaustive numerical investigation with existing models has then been followed by the development of an improved two equation model. The newly developed model has been validated for a wide range of flow problems and has thereafter been applied to the film cooling flow configuration under investigation in this study. Improvements in predictions obtained by the newly developed model have been highlighted and avenues of future work have been identified.

Date

2007

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Sumanta Acharya

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