Investigation of the Boundary Layer Behavior on Turbine Airfoils.
Abstract
Smoke flow visualization, hot-wire anemometer, and pressure distribution studies were conducted to determine some of the wake and pressure surface boundary layer transition region characteristics along an enlarged two-dimensional turbine airfoil model in cascade. Smooth surface as well as rough surface airfoils were used in the study, which utilized a continuous, subsonic, specially built wind-tunnel. The flow provided a range of blade chord Reynolds numbers from 7.9E + 5 1.5E + 6 at turbulence levels of 0.6 to 0.8%. A pressure surface transition region was found to exist from about S/C = 0.43 to the trailing edge for the smooth surface airfoil, and up to S/C = 0.1 for a rough surface airfoil. The transition region for a smooth surface was initiated through the formation of Goertler vortices which were found to break down through the action of traveling Tollmein-Schlichting waves. Other phenomena observed include various trailing edge vortex formations which may be linked to the intermittency of the boundary layer near the trailing edge, and a low frequency traveling wave formed in conjunction with the appearance of traveling waves. An empirical relationship was developed for the traveling wave frequency. Comparison was made with stability theory and empirical methods of predicting transition. Linear stability theory was found to predict the Goertler wavelength, but not that of the traveling waves.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1979
- Accession Number
- ADA075501
Entities
People
- Arnon Chait
- Lit. S. Han
- Wesley R. Cox
Organizations
- Ohio State University