Sensitivity of LES results from turbine rim seals to changes in grid resolution and sector size

O’Mahoney, Thomas S. D.; Hills, Nicholas J.; Chew, John W.

doi:10.1016/j.paerosci.2011.09.003

Cited by 16 publications

(10 citation statements)

References 5 publications

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“…LES for a 13.3 o sector did not show the very distinct low frequency peak in cavity pressure observed in URANS but showed increased amplitude over a range of frequencies [27]. Further studies investigated the sensitivity of LES to the simulation time, computational sector size and mesh resolution [28]. Increasing the computational sector size from 13.3 ∘ to 40 ∘ had a very small influence on the average and unsteady results.…”

Section: Large Eddy Simulationmentioning

confidence: 86%

“…The first openly published large-eddy simulation of turbine rim seal flows appear to be those by O'Mahoney et al [27,28] who considered the chute seal geometry for the University of Sussex test rig. However this followed a preliminary study by Autef [52] which suggested that LES could offer improvements over URANS techniques.…”

Section: Large Eddy Simulationmentioning

confidence: 99%

“…Such comparisons have shown mixed levels of agreement, as shown in the literature. 11,19,20,24–31 While conventional Reynolds-averaged Navier–Stokes (RANS) models sometimes give quantitative or qualitative trends in reasonable agreement with measurements, considerable uncertainties remain.…”

Section: Rotating Flow Modes and Cfd Modellingmentioning

confidence: 99%

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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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Section: Large Eddy Simulationmentioning

confidence: 86%

Section: Large Eddy Simulationmentioning

confidence: 99%

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Flow mechanisms in axial turbine rim sealing

Chew

Gao

Palermo

2018

Proceedings of the Institution of Mechanical Engineers, Part C:

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“…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: 92%

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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“…The test case presented in this performance study is a model of the experimental high pressure turbine test rig, extensively investigated in several studies [32]. Fig.…”

Section: Industrial Turbine Stage Rigmentioning

confidence: 99%