A combined computational fluid dynamics (CFD) and experimental study of interaction of main gas path and rim sealing flow is reported. The experiments were conducted on a two stage axial turbine and included pressure measurements for the cavity formed between the stage 2 rotor disk and the upstream diaphragm for two values of the diaphragm-to-rotor axial clearance. The pressure measurements indicate that ingestion of the highly swirling annulus flow leads to increased vortex strength within the cavity. This effect is particularly strong for the larger axial clearance. Results from a number of steady and unsteady CFD models have been compared to the measured results. Good agreement between measurement and calculation for time-averaged pressures was obtained using unsteady CFD models, which predicted previously unknown unsteady flow features. This led to fast response pressure transducer measurements being made on the rig, and these confirmed the CFD prediction.

Issue Section:
Gas Turbines: Heat Transfer and Turbomachinery
Keywords:
seals (stoppers), vortices, swirling flow, gas turbines, computational fluid dynamics, pressure measurement, rotors, diaphragms, pressure transducers
Topics:
Annulus, Cavities, Computational fluid dynamics, Disks, Flow (Dynamics), Pressure, Rotors, Turbines, Diaphragms (Mechanical devices), Diaphragms (Structural), Pressure measurement, Unsteady flow, Pressure transducers, Swirling flow, Vortices, Axial flow
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