Date of Award

12-1990

Document Type

Thesis

Degree Name

Master of Science in Aeronautical Engineering

Department

Department of Aeronautics and Astronautics

First Advisor

Paul I. King, PhD

Abstract

Convective heat transfer in a turbine cascade is examined for turbulence effects. Turbulence in the free stream is varied by injection of air through a jet-grid device upstream of the cascade. Pressure and flow patterns on the blade surface, and flow velocity in two components, are examined to determine the effect of the jet-grid. Velocity and velocity fluctuation in two components are measured. Local turbulence scales through the cascade passage are determined, and local turbulent energy dissipation rate is determined. Results indicate injection of air through the jet-grid changes the angle of incidence, and therefore changes the surface pressures and velocities on the blade. Heat transfer comparison is thereby invalidated. Variations in jet-grid plenum pressure change the turbulence microscale at the cascade entrance, but not the integral scale. Turbulence intensity is likewise relatively unaffected. Turbulence behavior in the passage indicates that velocity fluctuation and turbulence microscale are inversely related; turbulence intensity and microscale are not inversely related. With 6% freestream turbulence intensity, turbulence in the passage center is influenced first by events near the suction surface, then by events near the pressure surface. The primary vehicle for cross-stream diffusion is increased cross-stream velocity component fluctuations.

AFIT Designator

AFIT-GAE-ENY-90D-1

DTIC Accession Number

ADA230521

Download

Share

COinS