Fluid dynamics of a gas turbine wheel-space with ingestion

Carl Sangan, Yogesh Lalwani, Mike Owen, Gary Lock

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

This paper discusses the flow structure in typical rotor–stator systems with ingress and egress. Measurements of concentration, velocity and pressure were made using a rotating-disc rig which experimentally simulated hot gas ingestion into the wheel-space of an axial turbine stage. Externally-induced ingress through rim seals was generated from the non-axisymmetric pressures produced by the flow over the vanes and blades in the external annulus. Measurements were conducted using several single- and double-seal geometries and for a range of sealing flow rates and rotational speeds. The concentration measurements showed that the amount of ingress, which increased with decreasing sealing flow rate, depended on the seal geometry. The swirl velocity in the fluid core increased with decreasing sealing-flow rate, but outside the outer region in the wheel-space, it was largely unaffected by the seal geometry or by the amount of ingress. The radial distribution of static pressure, calculated from the measured swirl velocity in the core, was in good agreement with the pressures measured on the stator. The data for the double seals demonstrated that the ingested gas was predominately confined to the region between the seals near the periphery of the wheel-space; in the inner wheel-space, the effectiveness is shown to be significantly higher. The results are of direct relevance to the engine designer who uses complex rim seals often designed through computational fluid dynamics. The designer needs to know how much sealing air is required to prevent ingress, what is the effect of ingress on metal temperature and stresses, and how these factors are governed by the flow structure in the wheel-space.
Original languageEnglish
Pages (from-to)508-524
Number of pages17
JournalProceedings of the Institution of Mechanical Engineers Part A: Journal of Power and Energy
Volume228
Issue number5
Early online date27 Mar 2014
DOIs
Publication statusPublished - Aug 2014

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Fluid dynamics
Seals
Gas turbines
Wheels
Flow rate
Flow structure
Stators
Geometry
Rotating disks
Gases
Computational fluid dynamics
Turbines
Rotors
Engines
Fluids
Air
Metals

Cite this

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abstract = "This paper discusses the flow structure in typical rotor–stator systems with ingress and egress. Measurements of concentration, velocity and pressure were made using a rotating-disc rig which experimentally simulated hot gas ingestion into the wheel-space of an axial turbine stage. Externally-induced ingress through rim seals was generated from the non-axisymmetric pressures produced by the flow over the vanes and blades in the external annulus. Measurements were conducted using several single- and double-seal geometries and for a range of sealing flow rates and rotational speeds. The concentration measurements showed that the amount of ingress, which increased with decreasing sealing flow rate, depended on the seal geometry. The swirl velocity in the fluid core increased with decreasing sealing-flow rate, but outside the outer region in the wheel-space, it was largely unaffected by the seal geometry or by the amount of ingress. The radial distribution of static pressure, calculated from the measured swirl velocity in the core, was in good agreement with the pressures measured on the stator. The data for the double seals demonstrated that the ingested gas was predominately confined to the region between the seals near the periphery of the wheel-space; in the inner wheel-space, the effectiveness is shown to be significantly higher. The results are of direct relevance to the engine designer who uses complex rim seals often designed through computational fluid dynamics. The designer needs to know how much sealing air is required to prevent ingress, what is the effect of ingress on metal temperature and stresses, and how these factors are governed by the flow structure in the wheel-space.",
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