Accession Number:

ADA561733

Title:

Endwall Loss and Mixing Analysis of a High Lift Low Pressure Turbine Cascade (Preprint)

Descriptive Note:

Conference paper (preprint), 1 Jan 2011-1 Jan 2012

Corporate Author:

AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE

Personal Author(s):

• Lyall, M. E.
• King, Paul I.
• Sondergaard, Rolf

Report Date:

2012-05-01

Pagination or Media Count:

14.0

Abstract:

A high lift LPT profile designated L2A is used as a test bed for studying the origin of endwall mixing loss and the role of vortical structures in loss development. It is shown analytically and experimentally that the mixing forces within the endwall wake can be decoupled into either mean flow or turbulent forces, and can be further classified as either reversible or irreversible. Among the irreversible forces, mean flow shear is negligible compared to turbulent shear, suggesting that turbulence dissipation is the dominant cause of loss generation. As a result, the mean flow components of the vortical structures do not generate significant mixing losses. Rather than mixing effects, the mean flow of the vortices cause the suction surface boundary layer to separate inside the passage, thereby generating the large low energy regions typical of endwall flows. Losses are generated as the low energy regions mix out. This vortex separation effect is demonstrated with an experiment using a profile fence and pressure surface modification near the endwall.

Descriptors:

• *AERODYNAMIC CHARACTERISTICS
• *TURBINES
• BOUNDARY LAYER
• HIGH LIFT
• IRREVERSIBLE PROCESSES
• LOW ENERGY
• SHEAR PROPERTIES

Subject Categories:

• Aerodynamics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE