Effects of Suction and Injection Purge-Flow on the Secondary Flow Structures of a High-Work Turbine

Schuepbach, P.; Abhari, Reza S.; Rose, Martin G.; Germain, T.; Raab, I.; Gier, Jochen

doi:10.1115/1.4000485

Cited by 46 publications

(14 citation statements)

References 20 publications

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“…The increased strength of the rotor hub passage vortex and the increased penetration depth of flow with negative incidence has been reported by Ong et al (2012). Schuepbach et al (2010) reported on a decrease of efficiency by 0.6% per percent of injected purge mass flow based on measurements in a 1.5-stage high-pressure turbine. Zlatinov et al (2012) performed a combined study on hub and shroud leakage loss mechanisms, highlighting that by 1.5% of purge flow injection at the hub, turbine losses are increased by 12%.…”

Section: Introductionmentioning

confidence: 61%

Novel high-pressure turbine purge control features for increased stage efficiency

Schädler

Kalfas

Abhari

et al. 2017

J. Glob. Power Propuls. Soc.

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Rim seals throttle flow and have shown to impact the aerodynamic performance of gas turbines. The results of an experimental investigation of a rim seal exit geometry variation and its impact on the high-pressure turbine flow field are presented. A one-and-a-half stage, unshrouded and highly loaded axial turbine configuration with 3-dimensionally shaped blades and non-axisymmetric end wall contouring has been tested in an axial turbine facility. The exit of the rotor upstream rim seal was equipped with novel geometrical features which are termed as purge control features (PCFs) and a baseline rim seal geometry for comparison. The time-averaged and unsteady aerodynamic effects at rotor inlet and exit have been measured with pneumatic probes and the fast-response aerodynamic probe (FRAP) for three rim seal purge flow injection rates. Measurements at rotor inlet and exit reveal the impact of the geometrical features on the rim seal exit and main annulus flow field, highlighting regions of reduced aerodynamic losses induced by the modified rim seal design. Measurements at the rotor exit with the PCFs installed show a benefit in the total-to-total stage efficiency up to 0.4% for nominal and high rim seal purge flow rates. The work shows the potential to improve the aerodynamic efficiency by means of a well-designed rim seal exit geometry without losing the potential to block hot gas ingestion from the main annulus.

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Section: Introductionmentioning

confidence: 61%

Novel high-pressure turbine purge control features for increased stage efficiency

Schädler

Kalfas

Abhari

et al. 2017

J. Glob. Power Propuls. Soc.

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“…At a fixed mass flow ratio, increasing the circumferential velocity relative to the rotor also reduced the stage efficiency due to a decrease in the near-wall incidence angle to the rotor. Increasing statorrotor leakage flow resulted in higher dissipation around the passage vortex and lower overall efficiency in rotating rig measurements by Schuepbach, et al [10]. McLean, et al [11] found that coolant injection into the stator-rotor wheelspace generally decreased total-to-total stage efficiency, although discrete-hole coolant injection on the stator hub improved stage efficiency by energizing the stator airfoil wake and the rotor hub boundary layer.…”

Section: Review Of Relevant Literaturementioning

confidence: 98%

Endwall Heat Transfer for a Turbine Blade With an Upstream Cavity and Rim Seal Leakage

Lynch

Thole

Kohli

et al. 2013

Volume 3C: Heat Transfer

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Aerodynamic loss and endwall heat transfer for a turbine blade are influenced by complex vortical flows that are generated at the airfoil-endwall junction. In an engine, those flows interact with clearance gaps between stationary and rotating components, as well as with leakage flow that is designed to exhaust through the gaps. This paper describes experimental measurements of endwall heat transfer for a highpressure turbine blade with an endwall overlap geometry, as well as an upstream leakage feature that supplied swirled or unswirled leakage relative to the blade. For unswirled leakage, increasing its mass flow increased the magnitude and pitchwise uniformity of the heat transfer coefficient upstream of the blades although heat transfer further into the passage was unchanged. Leakage flow with swirl shifted the horseshoe vortex in the direction of swirl and increased heat transfer on the upstream blade endwall, as compared to unswirled leakage. For a nominal leakage mass flow ratio of 0.75%, swirled leakage did not increase area-averaged heat transfer relative to unswirled leakage. At a mass flow ratio of 1.0%, however, swirled leakage increased overall heat transfer by 4% due to an increase in the strength of the vortical flows.

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“…Additionally, the mixing of the exiting cold gas with the main flow and its interaction with secondary flow structures, such as the vane hub passage vortex, causes further aerodynamic losses. The later has, for example, been investigated by Schuepbach et al (2010) and Schädler et al (2016).…”

Section: Introductionmentioning

confidence: 99%

Large-Eddy Simulations of Rim Seal Flow in a One-Stage Axial Turbine

Hösgen

Meinke

Schröder

2020

J. Glob. Power Propuls. Soc.

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The flow field in a one-stage axial flow turbine with 30 stator and 62 rotor blades including the wheel space is investigated by large-eddy simulation (LES). The Navier-Stokes equations are solved using a massively parallel finite-volume solver based on a Cartesian mesh with immersed boundaries. The strict conservation of mass, momentum, and energy is ensured by an efficient cut-cell/level-set ansatz, where a separate level-set solver describes the motion of the rotor. Both solvers use individual subsets of a shared Cartesian mesh, which they can adapt independently. The focus of the analysis is on the flow field inside the rotor stator cavity between the stator and rotor disks. Two cooling gas mass flow rates are investigated for the same rim seal geometry. First, the time averaged flow field for both simulations is compared, followed by a detailed investigation of the unsteady flow field. The results for the cooling effectiveness are compared to experimental data. Both cases show good agreement with experimental data. It is shown that for the lower cooling gas mass flux several of the wheel space’s acoustic waves are excited. This is not observed for the higher cooling gas mass flux. The excited waves lead to stable, i.e., bounded, fluctuations inside the wheel space and result in a significantly higher hot gas ingestion.

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Effects of Suction and Injection Purge-Flow on the Secondary Flow Structures of a High-Work Turbine

Cited by 46 publications

References 20 publications

Novel high-pressure turbine purge control features for increased stage efficiency

Novel high-pressure turbine purge control features for increased stage efficiency

Endwall Heat Transfer for a Turbine Blade With an Upstream Cavity and Rim Seal Leakage

Large-Eddy Simulations of Rim Seal Flow in a One-Stage Axial Turbine

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