Flowfield Measurements for a Highly Turbulent Flow in a Stator Vane Passage

Abstract

Turbine vanes experience high convective surface heat transfer as a consequence of the turbulent flow exiting the combustor. Before improvements to vane heat transfer predictions through boundary layer calculations can be made, we need to understand how the turbulent flow in the inviscid region of the passage reacts as it passes between two adjacent turbine vanes. In this study, a scaled-up turbine vane geometry was used in a low-speed wind tunnel simulation. The test section included a central airfoil with two adjacent vanes. To generate the 20 percent turbulence levels at the entrance to the cascade, which simulates levels exiting the combustor, an active grid was used. Three-component laser-Doppler velocimeter measurements of the mean and fluctuating quantities were measured in a plane at the vane midspan. Coincident velocity measurements were made to quantify Reynolds shear stress and correlation coefficients. The energy spectra and length scales were also measured to give a complete set of inlet boundary conditions that can be used for numerical simulations. The results show that the turbulent kinetic energy throughout the inviscid region remained relatively high. The surface heat transfer measurements indicated high augmentation near the leading edge as well as the pressure side of the vane as a result of the elevated turbulence levels. [S0889-504X(00)02302-3]

Unsteady Heat Flux Measurements of Junction Flow With Reynolds Number and Freestream Turbulence Effects

“…Several efforts were made previously to understand the contributions of high freestream Tu and Re on timeaveraged endwall heat transfer in gas turbine vanes ( [15], [16]). Blair [12] and Dunn et al [13] were among the initial researchers who investigated the endwall heat flux rates between turbine cascade blades and reported an increase by a factor of 3 near the leading edge of endwall and turbine junction.…”

Effects of Inlet Turbulence and End-Wall Boundary Layer on Aerothermal Performance of a Transonic Turbine Blade Tip

“…As the now passes the downstream turbine vane passage, the turbulence level still remains high [4]. Porreca et al [5] measured the time average turbulence level which reaches a level up to 14% in the core of the secondary flows and the wake of the exit of the second stator.…”

Effects of High Intensity, Large-Scale Freestream Combustor Turbulence on Heat Transfer in Transonic Turbine Blades

“…Oldfield (1992, 1996) and the previous work by Holmberg (1996) and Holmberg and Pestian (1996) are the exceptions. Giel, et al (2000) Low speed 0.11 18% Barringer, et al (2002) Low speed 0.43 18% Wang, et al (1998) Low speed -20% Thole, et al (1994) Low speed 0.11 13% Low speed -10% Boyle, et al (1998) Low speed -17% Schauer and Pestian (1996) Low speed -20% Radomsky and Thole (2000) Transonic <0.1 5% Holmberg (1996) Low speed -13% Mehendale and Han (1992) …”

“…The streamwise velocity fluctuations (u') were shown to decrease through the blade passage, while cross-stream (v') and lateral (w') fluctuations increased. Detailed measurements using a 3 component LDV system were reported in Radomsky and Thole (2000) and showed that turbulence remains quite high throughout the passage. Length scale was shown to decrease through the blade passage, although not considerably.…”