Laminar-Turbulence Transition over the Rotor Disk in an Enclosed Rotor-Stator Cavity

Makino, Soichiro; Inagaki, Masahide; Nakagawa, Masaki

doi:10.1007/s10494-015-9619-z

Cited by 22 publications

(19 citation statements)

References 16 publications

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“…conditions between the two experiments and as compared to our system. the same investigation of Makino et al 11 Similarly, the peaks of the radial intensity distributions are located inside the boundary layers at z * r = 0.019 and z * s = 0.017 for the rotor and stator boundary layers, respectively. Figures 8 and 9 show instantaneous tangential velocity contours near the rotor (z * = 0.025) and stator (z * = 0.95) boundary layers; all velocity contours are normalised against U θ ,max = r 2 ω.…”

Section: 8supporting

confidence: 70%

“…These observations are in close agreement with previous investigations. 10,11 The velocity contours and iso-surfaces of the rotor boundary do not show any Type I spiral patterns (as would be identified by positive ) which suggests that turbulent transition here is not due to an inviscid cross-flow instability. This is consistent with the findings of Makino et al 11 who suggested that the structures are a result of the Type II streamline-curvature instabilities first identified by Itoh.…”

Section: 8mentioning

confidence: 72%

“…10,11 The velocity contours and iso-surfaces of the rotor boundary do not show any Type I spiral patterns (as would be identified by positive ) which suggests that turbulent transition here is not due to an inviscid cross-flow instability. This is consistent with the findings of Makino et al 11 who suggested that the structures are a result of the Type II streamline-curvature instabilities first identified by Itoh. 6 In particular, Makino et al suggested that the turbulent transition of the rotor-stator cavity could be a result of interactions between the dominant Type II modes and their secondary instability patterns, which is denoted as "mechanism B" in the investigation of Faller.…”

Section: 8mentioning

confidence: 72%

“…Either side of this region, the flow becomes turbulent as a likely result of the instability. Makino et al 11 conducted a similar numerical investigation and, at Re ω = 4 × 10 5 , found the rotor boundary layer to feature 16 spiral arms. These were suggested to be due to a Type II instability-which is in contrast to the conclusions of Séverac et al…”

Section: Introductionmentioning

confidence: 93%

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The effect of surface roughness on rotor-stator cavity flows

2018

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We are concerned with the CFD simulation of annular rotor-stator cavities using the general purpose second-order finite volume method (FVM) solver OpenFOAM ® and Large Eddy Simulation (LES) methods. Simulations of cavities with smooth surfaces are conducted at various Reynolds numbers, and the properties of the mean turbulent flows are validated against experimental and numerical data available in the literature. Comparisons show that second-order accurate FVM approaches can produce high-fidelity simulations of rotor-stator cavities to an acceptable accuracy and are therefore a viable alternative to the computationally intensive high-order methods. Our validated second-order FVM model is then combined with the parametric force approach of Busse and Sandham ["Parametric forcing approach to rough-wall turbulent channel flow," J. Fluid Mech. 712, 169-202 (2012)] to simulate cavities with a rough rotor surface. Detailed flow visualisations suggest that roughnessinduced disturbances propagate in the downstream direction of the rotor flow toward the outer wall of the cavity. The outer wall subsequently provides a passage to transport said roughness effects from the rough rotor layer to the smooth stator layer. We demonstrate that rotor-stator cavity flows are sensitive to even small roughness levels on the rotor surface alone.

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Section: 8supporting

confidence: 70%

Section: 8mentioning

confidence: 72%

Section: 8mentioning

confidence: 72%

Section: Introductionmentioning

confidence: 93%

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The effect of surface roughness on rotor-stator cavity flows

2018

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“…An operational Reynolds number of Re ω = 1 × 10 5 will be used in our simulations. The previous LES of Séverac et al 46 and Makino et al 47 remarked that Re ω = 1 × 10 5 is high enough to generate a turbulent stator but will leave a considerable portion of the rotor boundary layer within the laminar regime. First, a single-phase S P transport model is used to demonstrate the effects of nanofluids on the momentum and thermal distributions within the rotor-stator cavity.…”

Section: Introductionmentioning

confidence: 96%

On the heat transfer effects of nanofluids within rotor-stator cavities

2018

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Owing to the rapid development of a number of technological and industrial sectors, high-performance electronic devices are now ubiquitous in modern engineering and industrial applications. Effective heat management is crucial to the smooth operation of such devices, and sometimes conventional methods of heat transfer fail to deliver the required performance. Recent advances in the field of nanofluids are a promising route to improve heat-transfer performance, and this is our motivation. We propose two computational fluid dynamics models for a rotor-stator cavity operating at Re ω = 1.0 × 10 5 and filled with a fluid that consists of different volume fractions of Al 2 O 3 nanoparticles. The first model simulates the nanofluid mixture using a single-phase transport model, and the second approach uses a two-phase transport model that allows for the relative velocity between the particle and fluid phases. All simulations are conducted using the second-order accurate solver, Open-FOAM®, that is based on the finite volume method and using Large eddy simulation methods. Our results show that the higher volume fractions of Al 2 O 3 nanoparticles can achieve higher heat transfer rates, and at the same time, dilute nanoparticle concentrations have subtle effects on the momentum transport of the system. This is an advantage over micro-particle dispersion. Furthermore, we consider the effects of particle forces in the two-phase model, such as Brownian and thermophoresis forces, and suggest that the thermophoresis forces are the dominant effect within the cavity geometry.

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Experimental investigation of the microscale rotor–stator cavity flow with rotating superhydrophobic surface

Wang

Tang

et al. 2018

Exp Fluids

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Laminar-Turbulence Transition over the Rotor Disk in an Enclosed Rotor-Stator Cavity

Cited by 22 publications

References 16 publications

The effect of surface roughness on rotor-stator cavity flows

The effect of surface roughness on rotor-stator cavity flows

On the heat transfer effects of nanofluids within rotor-stator cavities

Experimental investigation of the microscale rotor–stator cavity flow with rotating superhydrophobic surface

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