Effects of wakes on the heat transfer in gas turbine cascades
Abstract
The interaction between consecutive blade rows can be expected to have important effects on the heat transfer in cooled gas turbine cascades. In the present study, the influence of the wake from a blade profile - traversed in front of a cooled gas turbine cascade in planes with varying distances from the leading edge - on the local heat transfer coefficient along the suction and pressure side has been analyzed. The investigation is part of a research program to develop experimentally verified numerical codes for heat transfer calculations. With the aid of a finite element program, the local heat transfer coefficients along the cooled blades are derived from surface and coolant temperature measurements. It is shown that in addition to the axial distances the orientation of the wake with respect to the leading edge is of dominant influence. In particular, the measurements demonstrate with increasing free stream turbulence levels a rapid rise of the heat transfer rate along the pressure surface as well as in the stagnation region. The laminar-turbulent transition is relocated towards the leading edge along the suction surface. The measurements are compared with those derived from flows with grid-produced turbulence. In general, slower transition behaviour is observed than foundwith numerical codes.
- Publication:
-
In AGARD Heat Transfer and Cooling in Gas Turbines 13 p (SEE N86-29823 21-07
- Pub Date:
- September 1985
- Bibcode:
- 1985htcg.agar.....W
- Keywords:
-
- Air Cooling;
- Boundary Layer Transition;
- Finite Element Method;
- Gas Turbines;
- Heat Transfer;
- Leading Edges;
- Turbine Blades;
- Turbulence Effects;
- Wakes;
- Flow Velocity;
- Free Flow;
- Heat Transfer Coefficients;
- Temperature Distribution;
- Turbulent Boundary Layer;
- Velocity Distribution;
- Fluid Mechanics and Heat Transfer