Large-eddy simulation of unsteady turbine rim sealing flows

Gao, Feng; Chew, John W.; Beard, Paul F.; Amirante, Dario; Hills, Nicholas J.

doi:10.1016/j.ijheatfluidflow.2018.02.002

Cited by 30 publications

(26 citation statements)

References 25 publications

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“…Compared to the chute seal smaller rim cavities, with similar cavity volumes, are used in axial and radial seals, aiming to reduce computational costs. This is considered reasonable as no resonance effects between the rim and inner cavities were identified in the experimental and numerical studies [19,29,30]. The surfaces of the rotor discs are highlighted with thick solid lines in the figure, and they spin at 7000rpm about the rotational axis, giving a rotational Reynolds number Re φ = Ωb 2 /ν = 2.6 × 10 6 based on the disc rim radius b and angular speed Ω.…”

Section: Rim Seal Configurations Studiedmentioning

confidence: 80%

“…Recent studies using LES have shown improved agreement with experimental measurements to those with RANS and URANS, in terms of pressure distribution and sealing effectiveness. These include studies by O'Mahoney et al [18,25], Gao et al [19] and Pogorelov et al [26]. This indicates that LES can give further insight into flow mechanisms in rim seals.…”

Section: Introductionmentioning

confidence: 91%

“…The first published experimental observation of these large-scale unsteady flow modes was reported by Cao et al [16] the T-C instability include Boudet et al [17], O'Mahoney [18] and Gao et al [19], and those proposing the K-H instability include Rabs et al [20], Chilla et al [21], Savov et al [22] and Horwood et al [15]. Another possible source of unsteadiness, suggested by Berg et al [23], are the Helmholtz and shallow cavity modes.…”

Section: Introductionmentioning

confidence: 99%

“…However, no further evidence was given. Gao et al [19] showed evidence of T-C like vortices using large-eddy simulation (LES) on a similar rim seal configuration. O'Mahoney et al [18] compared URANS and LES solutions of a chute rim seal and suggested the flow behaves in a similar way to a Couette flow system.…”

Section: Introductionmentioning

confidence: 99%

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Inertial waves in turbine rim seal flows

2020

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Rotating fluids are well-known to be susceptible to waves. This has received much attention from the geophysics, oceanographic and atmospheric research communities. Inertial waves, which are driven by restoring forces, for example the Coriolis force, have been detected in the research fields mentioned above. This paper investigates inertial waves in turbine rim seal flows in turbomachinery. These are associated with the large-scale unsteady flow structures having distinct frequencies, unrelated to the main annulus blading, identified in many experimental and numerical studies. These unsteady flow structures have been shown in some cases to reduce sealing effectiveness and are difficult to predict with conventional steady Reynolds-averaged Navier-Stokes (RANS) approaches. Improved understanding of the underlying flow mechanisms and how these could be controlled is needed to improve the efficiency and stability of gas turbines. This study presents large-eddy simulations for three rim seal configurations-chute, axial and radial rim seals-representative of those used in gas turbines. Evidence of inertial waves is shown in the axial and chute seals, with characteristic wave frequencies limited within the threshold for inertial waves given by classic linear theory (i.e. |f * /f rel | ≤ 2), and instantaneous flow fields showing helical characteristics. The radial seal, which limits the radial fluid motion with the seal geometry, restricts the Coriolis force and suppresses the inertial wave.

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Section: Rim Seal Configurations Studiedmentioning

confidence: 80%

Section: Introductionmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Inertial waves in turbine rim seal flows

2020

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“…This is consistent with O'Mahoney et al's observations. Recently, Gao et al [38,53,54] presented LES for the chute seal studied experimentally at the University of Oxford. A prescribed sector size of 13.33…”

Section: Large Eddy Simulationmentioning

confidence: 99%

Flow mechanisms in axial turbine rim sealing

Chew

Gao

Palermo

2018

Proceedings of the Institution of Mechanical Engineers, Part C:

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This paper presents a review of research on turbine rim sealing with emphasis placed on the underlying flow physics and modelling capability. Rim seal flows play a crucial role in controlling engine disc temperatures but represent a loss from the main engine power cycle and are associated with spoiling losses in the turbine. Elementary models that rely on empirical validation and are currently used in design do not account for some of the known flow mechanisms, and prediction of sealing performance with computational fluid dynamics (CFD) has proved challenging. CFD and experimental studies have indicated important unsteady flow effects that explain some of the differences identified in comparing predicted and measure sealing effectiveness. This review reveals some consistency of investigations across a range of configurations, with inertial waves in the rotating flow apparently interacting with other flow mechanisms which include vane, blade and seal flow interactions, disc pumping and cavity flows, shear layer and other instabilities, and turbulent mixing.

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Three‐dimensional large eddy simulation of wave characteristics of liquid film flow in a spinning disk reactor

Liu

et al. 2019

AIChE Journal

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The waves of liquid film flow play an important role on the process intensification in spinning disk reactors (SDRs). However, the mechanism of wave formation was still unclear. In this work, a three‐dimensional large eddy simulation was developed to investigate the mechanism, as well as the characteristics of waves in the SDR. Agreed with the imaging results, different wave patterns were identified as: smooth film, concentric, and spiral waves in spreading direction; sine‐like and pulse‐like waves in fluctuating direction. The radial and tangential relative movements among the layers of liquid film were found to dominate the formation of different wave patterns. Local average film thickness (havg) and local wave amplitude (Δh) ranged from 0 to 500 μm and 0 to 200 μm, respectively. The waves can improve the turbulent intensity and enlarge the specific surface area, resulting in the intensification of transfer processes.

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Large-eddy simulation of unsteady turbine rim sealing flows

Cited by 30 publications

References 25 publications

Inertial waves in turbine rim seal flows

Inertial waves in turbine rim seal flows

Flow mechanisms in axial turbine rim sealing

Three‐dimensional large eddy simulation of wave characteristics of liquid film flow in a spinning disk reactor

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