Turbulence and Complex Flow Phenomena in Multi-Stage Axial Turbomachines

The objective of this project is to measure the flow within axial turbomachines and use the data to address turbulence modeling issues. Measurements are performed in two-stage transparent machines located in an optically index matched facility, which allows unobstructed 2-D and Stereo PIV measurements. Data provide insight on blade-wake, wake- boundary layer and wake-wake interactions. This report examines and elucidates several phenomena: i. Variations in turbulence within a wake generated by an upstream IGV blade while being ingested by a rotor passage; ii. Non-uniform turbulence production and diffusion leading to formation of turbulent hot spots within a rotor wake due to flow non-uniformities generated by upstream wakes; iii. Unsteady flow caused by an upstream wake stabilizes the boundary layer on a rotor blade and reduces its momentum thickness; iv. Comparisons of data covering an entire stage to RANS predictions; and V. Measurements of subgrid-scale stresses and dissipation rate, and comparisons to model predictions as well as associated implications of spatial averaging in followed by ensemble averaging in sustially non-uniform flows.