Numerical investigation of buoyancy-induced flow in a sealed rapidly rotating disc cavity

Gao, Feng; Pitz, Diogo B.; Chew, John W.

doi:10.1016/j.ijheatmasstransfer.2019.118860

Cited by 27 publications

(48 citation statements)

References 32 publications

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“…The Boussinesq approximation is well accepted for studying heat convection in geophysics, but is not validated for centrifugal convection, which involves Coriolis forces and a stronger centrifugal force. Motivated by this and the mixed Nu − Ra scaling found in different studies, the present authors recently compared an incompressible code using the Boussinesq approximation to a fully compressible solver for both 2-D [12] and 3-D [13] models of Bohn et al's configuration B. Different degrees of agreement in shroud Nu between the two solvers were obtained for the 2-D and 3-D configurations, as plotted in Fig.…”

Section: Closed Rotating Cavitymentioning

confidence: 78%

“…It is also reported that changing the ratio between the radii of the shaft and the shroud (a/b) has negligible influence on Nu. Among the three geometries used in Bohn et al's experiment configuration B, in particular, has motivated a number of numerical [8][9][10][11][12][13] and theoretical [14] studies. This configuration is shown in Fig.…”

Section: Closed Rotating Cavitymentioning

confidence: 99%

“…The objectives of this paper are to further investigate the Ekman scrubbing effect identified in Ref. [13] and to present further LES studies for a configuration with axial throughflow using a compressible flow solver. Heat transfer results for the sealed and open cavities are compared.…”

Section: Open Rotating Cavity With Axial Throughflowmentioning

confidence: 99%

“…A brief description of these two solvers are given below, and readers are referred to Ref. [13] for further information.…”

Section: Description Of Configurations Studiedmentioning

confidence: 99%

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Ekman Layer Scrubbing and Shroud Heat Transfer in Centrifugal Buoyancy-Driven Convection

Gao

Chew

2021

Journal of Engineering for Gas Turbines and Power

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This paper presents large-eddy and direct numerical simulations of buoyancy-driven convection in sealed and open rapidly rotating cavities for Rayleigh numbers in the range 107-109, and axial throughflow Reynolds numbers 2000 and 5600. Viscous heating due to the Ekman layer scrubbing effect, which has previously been found responsible for the difference in sealed cavity shroud Nusselt number predictions between a compressible N-S solver and an incompressible counterpart using the Boussinesq approximation, is discussed and scaled up to engine conditions. For the open cavity with an axial throughflow, laminar Ekman layer behaviour of the mean flow statistics is confirmed up to the highest condition in this paper. The Buoyancy number Bo is found useful to indicate the influence of an axial throughflow. For the conditions studied the mean velocities are subject to Ra, while the velocity fluctuations are affected by Bo. A correlation, Nu0 = 0:169(Ra0)0:318, obtained with both the sealed and open cavity shroud heat transfer solutions, agrees with that for free gravitational convection between horizontal plates within 16% for the range of Ra0 considered. NOMENCLATURE

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Section: Closed Rotating Cavitymentioning

confidence: 78%

Section: Closed Rotating Cavitymentioning

confidence: 99%

Section: Open Rotating Cavity With Axial Throughflowmentioning

confidence: 99%

“…A brief description of these two solvers are given below, and readers are referred to Ref. [13] for further information.…”

Section: Description Of Configurations Studiedmentioning

confidence: 99%

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Ekman Layer Scrubbing and Shroud Heat Transfer in Centrifugal Buoyancy-Driven Convection

Gao

Chew

2021

Journal of Engineering for Gas Turbines and Power

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“…This can be considered as an implicit LES. The Semtex solver and its LES using SVV have been validated in number of applications, and recently have been successfully implemented in the simulations of gas turbine internal air systems [35][36][37].∇…”

Section: Methodsmentioning

confidence: 99%

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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