Heat Transfer and Flowfield Measurements in the Leading Edge Region of a Stator Vane Endwall

Abstract

The leading edge region of a first stage stator vane experiences high heat transfer rates especially near the end wall making it very important to get a better understanding of the formation of the leading edge vortex. In order to improve numerical predictions of the complex endwall flow, benchmark quality experimental data are required. To this purpose, this study documents the endwall heat transfer and static pressure coefficient distribution of a modern stator vane for two different exit Reynolds numbers (Reex = 6 × 105 and 1.2 × 106). In addition, laser Doppler velocimeter measurements of all three components of the mean and fluctuating velocities are presented for the stagnation plane in the leading edge region. Results indicate that the endwall heat transfer, pressure distribution and flowfield characteristics change with Reynolds number. The endwall pressure distributions show that lower pressure coefficients occur at the higher Reynolds number due to secondary flows. The stronger secondary flows cause enhanced heat transfer near the trailing edge of the vane at the higher Reynolds number. On the other hand the mean velocity, turbulent kinetic energy and vorticity results indicate that leading edge vortex is stronger and more turbulent at the lower Reynolds number. The Reynolds number also has an effect on the location of the separation point which moves closer to the stator vane at the lower Reynolds number.

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.…”

“…Radomsky and Thole [15] introduced T a freestream turbulence of 20% and found a 15% increase in endwall heat transfer underneath the horseshoe vortex core. Kang et al [16] reported that secondary flows contributed to the increase of the trailing edge endwall heat transfer of a vane. Ames et al [17] furthered the research efforts of understanding vane endwall heat transfer by introducing a mock aeroderivative combustion system upstream of a turbine vane cascade, where turbulence levels ranged from 0.7% to 14% and inlet Reynolds numbers based on true chord length and exit conditions were as high as 2,000,000.…”

Heat Transfer for a Turbine Blade With Nonaxisymmetric Endwall Contouring

“…The heat flux plates, depicted in Figure 2a, were manufactured in three sections, where the center section around the blades could be removed to install the flat or the contoured endwalls. For both endwall types, the heat flux plates consisted of serpentine inconel circuits encapsulated in kapton for a total thickness of 75 µm, with a 37 µm copper layer adhered to the top surface to increase heat flux uniformity (Kang et al [24]). The copper was painted with flat black paint to increase emissivity for infrared camera measurements.…”

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

“…The stator vane geometry was a twodimensional slice of an engine profile taken at the vane midspan. The construction and the development of the scaled-up stator turbine vane and the test section have been previously documented by Radomsky and Thole (1998) and Kang, et al (1998). The wind tunnel used in this study is recirculating with a corner test section, shown in Figure 1.…”