NDLI: Numerical Investigation of Contrasting Flow Physics in Different Zones of a High-Lift Low Pressure Turbine Blade

Content Provider	The American Society of Mechanical Engineers (ASME) Digital Collection
Author	Cui, J. Rao, V. Nagabhushana Tucker, P. G.
Copyright Year	2015
Abstract	Using a range of high fidelity large eddy simulations, the contrasting flow physics on the suction surface, pressure surface and endwalls of a low pressure turbine blade (T106A) was studied. The current paper attempts to provide an improved understanding of the flow physics over these three zones under the influence of different inflow boundary conditions. These include: (a) the effect of wakes at low and high turbulence intensity on the flow at mid-span and (b) the impact of the state of the incoming boundary layer on endwall flow features. On the suction surface, the pressure fluctuations on the aft portion significantly reduced at high Free-Stream Turbulence (FST). The instantaneous flow features revealed that this reduction at high FST is due to the dominance of ‘streak-based’ transition over the ‘Kelvin-Helmholtz’ based transition. Also, the transition mechanisms observed over the turbine blade were largely similar to those on a flat plate subjected to pressure gradients. On pressure surface, elongated vortices were observed at low FST. The possibility of the co-existence of both the Görtler instability and the severe straining of the wakes in the formation of these elongated vortices was suggested. While this was true for the cases under low turbulence levels, the elongated vortices vanished at higher levels of background turbulence. At endwalls, the effect of the state of the incoming boundary layer on flow features has been demonstrated. The loss cores corresponding to the passage vortex and trailing shed vortex were moved farther from the endwall with a turbulent boundary layer when compared to an incoming laminar boundary layer. Multiple horse-shoe vortices, which constantly moved towards the leading edge due to a low-frequency unstable mechanism, were captured.
Sponsorship	International Gas Turbine Institute
File Format	PDF
ISBN	9780791856659
DOI	10.1115/GT2015-43200
Volume Number	Volume 2C: Turbomachinery
Conference Proceedings	ASME Turbo Expo 2015: Turbine Technical Conference and Exposition
Language	English
Publisher Date	2015-06-15
Publisher Place	Montreal, Quebec, Canada
Access Restriction	Subscribed
Subject Keyword	Suction Turbulence Turbine blades Flat plates Pressure gradient Flow (dynamics) Pressure Physics Large eddy simulation Vortices Wakes Fluctuations (physics) Boundary-value problems Inflow Boundary layers Boundary layer turbulence
Content Type	Text
Resource Type	Article

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