Global Instability and Control of Low-Pressure Turbine Flows

Abstract : This final report covers the 35-month period from February 1, 2003, the inception of the grant, to its end on December 31, 2005. Within the present effort BiGlobal primary and secondary (Floquet) instability analyses of Low Pressure Turbine (LPT) flows were performed for the first time. The T-106/300 LPT blade was selected and used for the analyses reported herein. In addition, two- and three-dimensional direct numerical simulations (DNS) were employed respectively in order to provide the nonparallel steady and unsteady two-dimensional basic flows to be analyzed and in order to cross-validate primary and secondary BiGlobal instability analysis results. Calculations were performed at chord Reynolds numbers of 900 and 5000 using both structured and unstructured grids. Finally, the first-ever transient growth analysis of a nonparallel flow field was performed in the context of the LPT flow investigated herein. In the entire range investigated, unstable three-dimensional modes were discovered; as the three-dimensional flow approaches the two-dimensional limit, the time-periodic basic state is recovered.