Endwalls impose a challenge to cool because of the complex system of secondary flows and separation lines disrupting surface film coolant coverage. The interaction of film cooling flows with secondary flow structures is coupled. The momentum exchange of the film coolant with the mainstream affect the formation the secondary flows, which in turn affect the coolant coverage. Therefore, to develop better endwall cooling schemes, a good understanding of passage aerodynamics as affected by interactions with coolant flows is required. This study presents experimental and computational results for cascade representing the first stage nozzle guide vane of a high-pressure gas turbine. The cascade is subsonic, linear, and stationary with an axisymmetrically-contoured endwall. Two cooling flows are simulated; upstream combustor liner coolantin the form of an aero-thermal profile simulated in the approach flow and endwall slot film cooling, which is injected immediately upstream of the passage inlet. The experiment is run with engine representative combustor exit flow turbulence intensity and integral length scales, with high turbine passage exit Reynolds number of 1.61x106. Measurements are performed with various slot film cooling mass flow rate to mainstream flow rate ratios (MFR). Aerodynamic effects are documented with five-hole probe measurements at the exit plane. Varying the slot film cooling MFR results in minimal effects on total pressure loss for the range tested. Vorticity distributions show a very thin, yet intense, cross-pitch flow on the contoured endwall side. Coolant distribution fields that were previously presented for the same cascade are discussed in context of the aerodynamic measurements. A coolant vorticity parameter presenting the advective mixing of the coolant due to secondary flow vorticity is introduced. This parameter gives developers a new prospective on aerodynamic-thermal performance associated with cooled turbine endwall. The numerical study is conducted for the same test section geometry and is run under the same conditions. The applicability of using RANS turbulence closure models for simulating this type of flow is discussed. The effects of including the combustor coolant in the approach flow is also briefly discussed in context of the numerical results.
|Original language||English (US)|
|Title of host publication||Turbomachinery|
|Publisher||American Society of Mechanical Engineers (ASME)|
|State||Published - 2018|
|Event||ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition, GT 2018 - Oslo, Norway|
Duration: Jun 11 2018 → Jun 15 2018
|Name||Proceedings of the ASME Turbo Expo|
|Other||ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition, GT 2018|
|Period||6/11/18 → 6/15/18|
Bibliographical noteFunding Information:
The authors would like to acknowledge Solar Turbines Inc. for their financial support and Minnesota Supercomputing Institute for providing computational resources for conducting this study.
© Copyright 2018 ASME.
- Coolant vorticity
- Endwall contouring
- Film cooling
- Passage vortex
- Secondary flows
- Total pressure loss