A borescope design tool for laser measurements in fluids

Figueiredo, A. J. Carvalho; Jones, Robin; Sangan, Carl M.; Cleaver, David

doi:10.1016/j.optlaseng.2019.105874

Cited by 6 publications

(2 citation statements)

References 16 publications

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“…towards the rotor). The borescope and optical pathway was developed in-Sangan TURBO-21-1170 10 house and is documented in Carvalho Figuereido et al [15,16]; the borescope illumination cone is shown in Fig. 3.…”

Section: Optical Designmentioning

confidence: 99%

Vortex Tracking of Purge-Mainstream Interactions in a Rotating Turbine Stage

Mesny

Glozier

Pountney

et al. 2021

Journal of Turbomachinery

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The use of purge flow in gas turbines allows for high turbine entry temperatures, which are essential to produce high cycle efficiency. Purge air is bled from the compressor and reintroduced in the turbine to cool vulnerable components. Wheel-spaces are formed between adjacent rotating and stationary discs, with purge air supplied at low radius before exiting into the mainstream gas-path through a rim-seal at the disc periphery. An aerodynamic penalty is incurred as the purge flow egress interacts with the mainstream. This study presents unparalleled three-dimensional velocity data from a single-stage turbine test rig, specifically designed to investigate egressmainstream interaction using optical measurement techniques. Volumetric Velocimetry is applied to the rotating environment with phase-locked measurements used to identify and track the vortical secondary flow features through the blade passage. A baseline case without purge flow is compared to experiments with a 1.7% purge mass fraction; the latter was chosen to ensure a fully sealed wheel-space. A non-localised vortex tracking function is applied to the data to identify the position of the core centroids. The strength of the secondary-flow vortices was determined by using a circulation criterion on rotated planes aligned to the vortex filaments........[abridged]

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Section: Optical Designmentioning

confidence: 99%

Vortex Tracking of Purge-Mainstream Interactions in a Rotating Turbine Stage

Mesny

Glozier

Pountney

et al. 2021

Journal of Turbomachinery

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“…The borescopes for both optical methods were designed using detailed ray-tracing computational modelling and standard optical components. The design process used to develop the borescopes is the subject of another publication [44].…”

Section: Effectiveness Measurements In the Wheel-spacementioning

confidence: 99%

An Advanced Single-Stage Turbine Facility for Investigating Nonaxisymmetric Contoured Endwalls in the Presence of Purge Flow

Jones

Pountney

Cleton

et al. 2019

Journal of Engineering for Gas Turbines and Power

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In modern gas turbines, endwall contouring (EWC) is employed to modify the static pressure field downstream of the vanes and minimize the growth of secondary flow structures developed in the blade passage. Purge flow (or egress) from the upstream rim-seal interferes with the mainstream flow, adding to the loss generated in the rotor. Despite this, EWC is typically designed without consideration of mainstream–egress interactions. The performance gains offered by EWC can be reduced, or in the limit eliminated, when purge air is considered. In addition, EWC can result in a reduction in sealing effectiveness across the rim seal. Consequently, industry is pursuing a combined design approach that encompasses the rim-seal, seal-clearance profile, and EWC on the rotor endwall. This paper presents the design of and preliminary results from a new single-stage axial turbine facility developed to investigate the fundamental fluid dynamics of egress–mainstream flow interactions. To the authors' knowledge, this is the only test facility in the world capable of investigating the interaction effects between cavity flows, rim seals, and EWC. The design of optical measurement capabilities for future studies, employing volumetric velocimetry (VV) and planar laser-induced fluorescence (PLIF), is also presented. The fluid-dynamically scaled rig operates at benign pressures and temperatures suited to these techniques and is modular. The facility enables expedient interchange of EWC (integrated into the rotor bling), blade-fillet and rim-seal geometries. The measurements presented in this paper include: gas concentration effectiveness and swirl measurements on the stator wall and in the wheel-space core; pressure distributions around the nozzle guide vanes (NGV) at three different spanwise locations; pitchwise static pressure distributions downstream of the NGV at four axial locations on the stator platform.

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