Investigation of 3D Unsteady Flows in a Two-Stage Shrouded Axial Turbine Using Stereoscopic PIV and FRAP: Part II — Kinematics of Shroud Cavity Flow

Yun, Yong Il; Porreca, L.; Kalfas, A. I.; Song, Seung Jin; Abhari, Reza S.

doi:10.1115/gt2006-91020

Cited by 13 publications

(6 citation statements)

References 16 publications

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“…This is attributed to the growth of the tip passage vortex downstream of the cavity and mixing with the leakage layer. The formation and the evolution of this vortex are documented in the 3D particle image velocimetry measurements by Yun et al [21]. However, in the LHSS case, the influence of the leakage flow is reduced and the loss core at tip is weakened.…”

Section: Labyrinth-honeycomb Sealmentioning

confidence: 90%

Control of shroud leakage flows to reduce mixing losses in a shrouded axial turbine

Gao

Zheng

Yue

et al. 2011

Proceedings of the Institution of Mechanical Engineers, Part C:

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The losses caused by the leakage flows through the rotor tip clearance, and the mixing losses by the re-entering leakage into the main flow are considerable parts of the total losses in turbines. The main reason for the mixing losses is the different velocity components of main and leakage flows. This leads to shear stresses which cause increased turbulence and losses. This article presents a numerical investigation on three different configurations to control the leakage flows: (a) turning vanes are fixed onto the casing between the fins to turn the shroud leakage flow into the main flow direction in order to reduce the circumferential mixing losses; (b) honeycomb bands are inserted into the casing to weaken the leakage flow in the circumferential direction and reduce the circumferential mixing losses due to the special hexagon structure; and (c) downstream edge of the cavity is chamfered to reduce the radial velocity component of the leakage jet and the separation at the downstream edge, and also to reduce the streamwise mixing losses. A 1.5-stage axial turbine with high-aspect ratio blading was used in this study to investigate the sealing designs as mentioned. The flow simulation results of the three configurations were analysed and compared in this article.

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Section: Labyrinth-honeycomb Sealmentioning

confidence: 90%

Control of shroud leakage flows to reduce mixing losses in a shrouded axial turbine

Gao

Zheng

Yue

et al. 2011

Proceedings of the Institution of Mechanical Engineers, Part C:

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“…Giess and Kost [9] measured flow fields in a rotating annular turbine cascade using pneumatic probes and pressure taps. Recently, PIV has been widely used to measure unsteady three-dimensional velocity fields in rotating rigs to investigate such phenomena as blade row interaction between a turbine stator and rotor, flows in shrouded cavities affected by axial turbine, and unsteady flows within a compressor passage [10][11][12]. Such tests are more costly and require more complicated measuring devices.…”

Section: Introductionmentioning

confidence: 99%

One-pitch passage designed inversely with a single blade for cascade experiments

et al. 2010

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A linear cascade experimental apparatus often consists of only a few cascade blades. Advantages to this experimental arrangement are increased by the use of larger cascade blades, a lower mass flow rate, a corresponding decrease in required power, and easier optical access within the cascade passage. However, fewer cascade blades in the cascade row make it difficult to establish periodic flow conditions between blades compared to infinite cascade model experiments. Generally, removing fluid from the cascade walls or adjusting tailboards located downstream of the cascade are common methods to establish periodic flow conditions through the cascade blades. In this study, a passage for cascade experiments is designed to satisfy infinite cascade flow conditions without any flow control or tailboards. A one-pitch at cascade row is adopted as its width and only a single cascade blade is installed within the passage. The surface isentropic Mach number distribution on the blade is chosen for the existence of infinite cascade flow conditions, and 14 geometric design variables related to the passage shape are applied to the design of a one-pitch passage by using a genetic algorithm. Flow structures within a passage designed using a genetic algorithm match with those obtained with the infinite cascade flow condition. Computed results obtained with a single cascade blade show that infinite cascade flow conditions can be obtained by modifying only the passage walls of the cascade experimental apparatus.

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“…Jones et al [12] constructed a very advanced test turbine facility equipped with the CO 2 PLIF system with optical access through a borescope. Yun et al [13,14] used Stereo PIV to study the flow in a rotor shroud cavity.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of the Unsteady Stator/Rotor Wake Characteristics Downstream of an Axial Air Turbine

Duda

Jelı́nek²,

Milčák

et al. 2021

IJTPP

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A feasibility study of velocity field measurements using the Particle Image Velocimetry (PIV) method in an axial air turbine model is presented. The wakes past the blades of the rotor wheel were observed using the PIV technique. Data acquisition was synchronized with the shaft rotation; thus, the wakes were phase averaged for statistical analysis. The interaction of the rotor blade wakes with the stator ones was investigated by changing the stator wheel’s angle. The measurement planes were located just behind the rotor blades, covering approximately 3 cm × 3 cm in axial × tangential directions. The spatial correlation function suggests that the resolution used is sufficient for the large-scale flow-patterns only, but not for the small ones. The scales of fluctuations correspond to the shear layer thickness at the mid-span plane but, close to the end-wall, they contain larger structures caused by the secondary flows. The length-scales of the fluctuations under off-design conditions display a dependence on the area of the stator and rotor wakes cross-sections, which, in turn, depend on their angle. The obtained experimental data are to be used for the validation of mathematical simulation results in the future.

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Investigation of 3D Unsteady Flows in a Two-Stage Shrouded Axial Turbine Using Stereoscopic PIV and FRAP: Part II — Kinematics of Shroud Cavity Flow

Cited by 13 publications

References 16 publications

Control of shroud leakage flows to reduce mixing losses in a shrouded axial turbine

Control of shroud leakage flows to reduce mixing losses in a shrouded axial turbine

One-pitch passage designed inversely with a single blade for cascade experiments

Experimental Investigation of the Unsteady Stator/Rotor Wake Characteristics Downstream of an Axial Air Turbine

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