A Combined Experimental/Computational Study of Flow in Turbine Blade Cooling Passage: Part II — Numerical Simulations

Abstract

A combined experimental/computational study has been performed for flow in rotating serpentine passages which approximate internal cooling passage for turbine blades. Experimental results are presented in the companion, Part I. The numerical simulations were performed using detailed experimental velocity profile measurements, documented in Part I, to set inflow conditions. Incompressible flow predictions with a two-layer k-ε turbulence model, which isolated the Coriolis induced secondary flow, agreed well with the measured velocities. Fluid density variations were included in compressible flow simulations which show the impact of the centrifugal buoyancy force in addition to the Coriolis force. Comparison with previously acquired heat transfer data indicates that the buoyancy force may be important in gas turbine applications.

A Combined Experimental/Computational Study of Flow in Turbine Blade Cooling Passage: Part I — Experimental Study

“…Thus, buoyancy further increases heat transfer at the high pressure surface while suppressing that at the low pressure surface. Compressible flow simulations, McGrath and Tse (1994), show that the total effect of Coriolis and buoyancy forces lead to an increase in streamwise velocity to 1.4U, along the high pressure surface and this yields an increase in Nu by 30%, which is still short of the 100% measured by . However, it can be inferred from the present experimental results that the convection of cool fluid from the center of the passage toward the high pressure surface by Coriolis induced secondary flows greatly increases the temperature difference between the wall and the coolant.…”

“…Due to entrance effect, the streamwise velocities on the leading side are higher than those on the trailing side. McGrath and Tse (1994) show that the high velocity discharged from the trailing side of the delivery pipe is deflected onto the leading side of the model upon impact with the plenum wall. The flow entering the model is angled toward the leading side and this gives rise to the resulting high velocities on that side.…”

“…Coriolis-induced secondary flow plays an important role in the heat transfer. The heat transfer and incompressible flow simulations, McGrath and Tse (1994), show a 40% increase in heat transfer due to the convection of cool fluid to the vicinity of the wall. The tangential velocities close to the trailing surface are small.…”

“…The results presented in this paper are taken from a larger set reported in Tse, et al (1994). Computational procedures, results and conclusions from the theoretical analyses are presented in the companion Part II paper, McGrath and Tse (1994). Figure 1 shows the flow circuit for the rotating turbine blade rig.…”

Computation of Flow and Heat Transfer in Rotating Two-Pass Square Channels by a Reynolds Stress Model

“…They indicated that either a low Reynolds number k -c model, two-layer k -c model or second-moment closure model is needed for accurate prediction of flow and heat transfer for this complex flaw situation. McGrath and Tse (1995) performed the computation on the four pass, serpentine passage with three 180° turns which is identical to that of Wagner et al (1991) using the kc turbulence model with two wall treatments: the generalized wall function and the classical Van-Driest mixing length formulation. The two-layer wall integration turbulence model provides improvement over the wall function simulation.…”