Transition on Turbine Blades and Cascades at Low Reynolds Numbers.
Final rept. 1 Nov 95-9 Jul 96,
WRIGHT LAB WRIGHT-PATTERSON AFB OH
Pagination or Media Count:
Unpredicted losses in the low pressure turbine during operation at high altitudes has stimulated current interest in transition, and separation at low Reynolds numbers. In the turbine, free stream turbulence levels or unsteadiness resulting from vane wakes, passage vorticies, and end wall horseshoe vorticies exceeds the unsteadiness levels associated with a fully turbulent boundary layer. Transition and transition length are found to be a function of both turbulence intensity and length scale although there are no empirical relationships to be found in the literature which include both. An experimental and computation effort was undertaken to investigate the effect of turbulence intensity, and turbulence length scale on transition location, and transition length scale on transition location, and transition length in a Langston turbine cascade for solidities of 1.075 and 0.84 at Reynolds numbers of 50K to 2000K. Experimental observations of transition at turbulence levels of 1 and 10 for three integral turbulence scales indicate a relative lack of sensitivity to turbulence level and scale for the momentum thickness transition location, but a sensitivity to both for transition length.
- Fluid Mechanics
- Jet and Gas Turbine Engines