Accession Number:

ADA608202

Title:

Unsteady Aerodynamic Interaction in a Closely Coupled Turbine Consistent with Contra-Rotation

Descriptive Note:

Interim rept. 4 Aug 2012-4 Aug 2014

Corporate Author:

AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH AEROSPACE SYSTEMS DIR

Report Date:

2014-08-01

Pagination or Media Count:

167.0

Abstract:

A significant design concern for turbomachinery parts is forced vibrational response due to unsteady pressure fields. Shortened component lives, increased maintenance costs, and catastrophic engine failure can result due to unmitigated vibrational stresses. Geometry changes, increased airfoil count and wall thickness, and the inclusion of damping systems are a few of the current strategies employed by designers in order to move modal frequencies out of the engine running range or reduce the vibrational stresses on the airfoil. However, these techniques have a negative impact on performance, system weight, andor life cycle cost. The focus of the study presented here was to investigate the reaction between the blade and downstream vane of the stage-and-a-half High Impact Technologies HIT Research Turbine via CFD analysis and experimental data. Code Leoa Reynolds-Averaged Navier-Stokes RANS flow solver with the two-equation Wilcox 1998 k-969 turbulence modelwas used as the numerical analysis tool for comparison for all of the experiments conducted, which includes two- and three-dimensional geometries and both time-averaged and time-accurate simulations. The rigorous blade and downstream vane interaction study was accomplished by first testing the midspan and quarter-tip two-dimensional geometries of the blade in a linear transonic cascade. The effects of varying the incidence angle and pressure ratio on the pressure distribution were captured both numerically and experimentally. This was used during the stage-and-one-half post-test analysis to confirm that the target corrected speed and pressure ratio were achieved. Then, in a full annulus facility, the first vane itself was tested in order to characterize the flow field exiting the vane that would be provided to the blade row during the rotating experiments. Finally, the full stage-and-a-half Research Turbine was tested in the full annulus cascade with a data resolution not seen in any studies to date.

Subject Categories:

  • Hydraulic and Pneumatic Equipment

Distribution Statement:

APPROVED FOR PUBLIC RELEASE