The effects of manufacturing variability on turbine vane performance

Gas turbine vanes have airfoil shapes optimized to deliver specific flow conditions to turbine rotors. The limitations of the manufacturing process with regards to accuracy and precision mean that no vane will exactly match the design intent. This research effort is an investigation of the effects of manufacturing-induced geometry variability on the performance of a transonic turbine vane. Variability is characterized by performing Principal Components Analysis (PCA) on a set of measured vanes and then applied to a different vane design. The performance scatter of that design is estimated through Monte Carlo analysis. The effect of a single PCA mode on performance is estimated and it is found that some modes with lower geometric variability can have greater impact on performance metrics. Linear sensitivity analysis, both viscous and inviscid, is carried out to survey performance sensitivity to localized surface perturbations , and tolerances are evaluated using these results. The flow field is seen to be practically insensitive to shape changes upstream of the throat. Especially sensitive locations like the throat and trailing edge are investigated further through nonlinear sensitivity analysis. Acknowledgments Completing this work has placed me gladly in the debt of many who have helped me get to and through MIT. Prof. Dave Darmofal's insight and patience have been instrumental in improving both this thesis and the student who wrote it. I consider myself fortunate to have been the beneficiary of his guidance. I am thankful to Prof. Mark Drela for creating MISES and for supporting it by answering my numerous questions. Similarly I would like to thank the ProjectX team, particularly Garrett Barter, J.M. Modisette, and Todd Oliver, for all their help. The wisdom and kind assistance of Prof. Rob Miller are also much appreciated. I owe a debt of gratitude to Rolls-Royce for establishing the Sir Frank Whittle Fellowship which provided the means for me to realize my dream of attending MIT. Additionally, the company provided invaluable data and the expertise of Dr. I would not trade my time at MIT for anything, although it has been difficult at times. I've been lucky to have had some very good people to lean on for support and balance. My roommates and the varsity crew team helped my well-being immeasurably. Most of all, I must thank my family for their support throughout this work and throughout my life. Their encouragement and sacrifices on my behalf are the ultimate source …