Flowfield Measurements in the Endwall Region of a Stator Vane

Abstract

A first stage stator vane experiences high heat transfer rates particularly near the end wall where strong secondary flows occur. In order to improve numerical predictions of the complex endwall flow at low speed conditions, benchmark quality experimental data are required. This study documents the flowfield in the endwall region of a stator vane that has been scaled up by a factor of nine while matching an engine exit Reynolds number of Reex = 1.2·106. Laser Doppler velocimeter (LDV) measurements of all three components of the mean and fluctuating velocities are presented for several flow planes normal to the turbine vane. Measurements indicate that downstream of the minimum static pressure location on the suction surface of the vane, an attenuated suction side leg of the horseshoe vortex still exists. At this location, the peak turbulent kinetic energy coincides with the center of the passage vortex location. These flowfield measurements were also related to previously reported convective heat transfer coefficients on the endwall showing that high Stanton numbers occur where the passage vortex brings mainstream fluid towards the vane surface.

Heat transfer and film-cooling for the endwall of a first stage turbine vane

“…Fig. 3a shows the secondary flowfield vectors, as reported by Kang and Thole [9], for a case with a uniform temperature field and a turbulent boundary layer that had a thickness which was 9% of the span and a momentum Reynolds number of 3340. These measurements, where the location is illustrated on the turbine vane inset, agree with the Langston model.…”

“…In general, there are some slight disagreements in the different flow models that have been proposed but, for the most part, these flow models, which are primarily based on uniform inlet profiles except for the turbulent endwall boundary layers, agree on the existence of the leading edge and passage vortices. Experimental flowfield data presented by Bailey [6], Moore et al [7], Gregory-Smith and Cleak [8], and Kang et al [9] have all quantified some aspects of the secondary flows. All of these studies, however, have had an inlet boundary condition of a uniform flow except for a turbulent endwall boundary layer such as that shown in Fig.…”

“…(a) Measured secondary flows in a turbine vane passage with a two-dimensional turbulent boundary layer[9] and (b) for a case simulating the upstream effects of a combustor liner with combustor-turbine leakage flow[15].…”