The computation of flow development through stationary and rotating U-ducts of strong curvature

Iacovides, Hector; Launder, B. E.; Li, H.Y.

doi:10.1016/0142-727x(95)00056-v

Cited by 67 publications

(46 citation statements)

References 10 publications

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“…This pressure gradient is strong enough to reverse the slow moving fluid creating secondary flows [8] as the fluid streamlines are not parallel to the pressure gradient. This three-dimensionality has been explored in depth in computational studies by Iacovides et al [9]. It has been shown that the pressure drop around the bend is dependent on the presence of separation at the inner wall of the bend, the strength of the three-dimensionality and its associated losses [10].…”

Section: Flow Around U-bendmentioning

confidence: 99%

Application of pressure-sensitive paint to low-speed flow around a U-bend of strong curvature

Quinn¹,

Gongora-Orozco²,

Kontis³

et al. 2013

Experimental Thermal and Fluid Science

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Two in-house Pressure-Sensitive Paint (PSP) formulations have been developed and tested in the low-speed regime on the flow around a U-bend of strong curvature. The two PSP formulations use trisBathophenanthroline Ruthenium Perchlorate (Ru (II)) and Platinum tretakis (pentafluorophenyl) Porphyrin (PtTFPP) as their photoactive molecules, incorporated in identical sol-gel matrices. Ru (II) emits a broad peak centered at 610nm while PtTFPP emits a much narrower peak at 650nm. The paints were illuminated using two in-house constructed blue LED lights with peak emission of 468nm. These luminophores have been tested with gauge inlet pressures of 3000 and 1250 Pa respectively. A further sample was tested with a gauge pressure of 500 Pa. In-situ calibration was utilized to minimize the temperature dependency change between wind-on and wind-off images. Both paints captured the flow characteristics and gave predictable surface pressure maps despite the challenges inherent with using such low pressures. Keywords: PSP, low-speed, U-bend, internal flow INTRODUCTIONSeveral researchers have attempted to use pressuresensitive paints (PSP) at low speeds despite the inherent difficulties with such applications [1,2,3,4,5,6,7]. Of these researchers Bell [3] and Le Sant [7] managed extremely low errors (± 50 Pa). However, all of the applications of PSP to low-speed flow have been performed in large-scale wind tunnels. To this end it was decided to test the PSP formulations in use at the University of Manchester on a low-speed, internal flow.

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Section: Flow Around U-bendmentioning

confidence: 99%

Application of pressure-sensitive paint to low-speed flow around a U-bend of strong curvature

Quinn¹,

Gongora-Orozco²,

Kontis³

et al. 2013

Experimental Thermal and Fluid Science

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“…Fewer investigations of flow subjected to both strong curvature and rotation for smooth wall U-bends or serpentine passages have been reported in the literature. 8,9,21,22 In one computational study, 11 it was reported that low-Re ASM agreement when the curvature and Coriolis forces oppose one another. In order to gain additional insight into the coupled effect of rotation and curvature, direct numerical simulations for a fully developed, smooth wall, isothermal, serpentine passage have been conducted.…”

Section: Introductionmentioning

confidence: 99%

“…[6][7][8][9] These experiments have served as validation databases for RANS computations with eddy viscosity models ͑EVM͒, algebraic stress models ͑ASM͒, and full second moment closure models ͑SMC͒. [10][11][12][13][14][15][16][17][18][19] While curvaturecorrected EVM's have met with some success, 17,20 it is generally recognized that SMC models are required to capture the strong anisotropy and secondary flow that exists in such flows. The success of a particular turbulence model depends on available databases for their design, calibration, and validation.…”

Section: Introductionmentioning

confidence: 99%

Direct numerical simulations of turbulent flow through a stationary and rotating infinite serpentine passage

Laskowski

Durbin

2007

Physics of Fluids

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Serpentine passages are found in a number of engineering applications including turbine blade cooling passages. The design of effective cooling passages for high-temperature turbine blades depends in part on the ability to predict heat transfer, thus requiring an accurate representation of the turbulent flow field. These passages are subjected to strong curvature and rotational effects, and the resulting turbulent flow field is fairly complex. An understanding of the flow physics for flows with strong curvature and rotation is required in order to improve the design of turbine blade cooling passages. Experimental measurements of certain turbulence quantities for such configurations can be challenging to obtain, especially near solid surfaces, making the serpentine passage an ideal candidate for a direct numerical simulation (DNS). A DNS study has been conducted to investigate the coupled effect of strong curvature and rotation by simulating turbulent flow through a fully developed, smooth wall, round-ended, isothermal serpentine channel subjected to orthogonal mode rotation. The geometry investigated has an average radius of curvature R c /Î´=2.0 in the curved section and dimensions 12Ï€Î´Ã-2Î´Ã-3Ï€Î´ in the streamwise, transverse, and spanwise directions. The computational domain consists of periodic inflow/outflow boundaries, two solid wall boundaries, and periodic boundaries in the spanwise direction. The simulations were conducted for Reynolds number, Re b =5600, and rotation numbers, Ro b,z =0 and 0.32. Differences observed between the stationary and rotating cases are discussed in terms of the mean velocity, secondary flow, and Reynolds stresses. Serpentine passages are found in a number of engineering applications including turbine blade cooling passages. The design of effective cooling passages for high-temperature turbine blades depends in part on the ability to predict heat transfer, thus requiring an accurate representation of the turbulent flow field. These passages are subjected to strong curvature and rotational effects, and the resulting turbulent flow field is fairly complex. An understanding of the flow physics for flows with strong curvature and rotation is required in order to improve the design of turbine blade cooling passages. Experimental measurements of certain turbulence quantities for such configurations can be challenging to obtain, especially near solid surfaces, making the serpentine passage an ideal candidate for a direct numerical simulation ͑DNS͒. A DNS study has been conducted to investigate the coupled effect of strong curvature and rotation by simulating turbulent flow through a fully developed, smooth wall, round-ended, isothermal serpentine channel subjected to orthogonal mode rotation. The geometry investigated has an average radius of curvature R c / ␦ = 2.0 in the curved section and dimensions 12␦ ϫ 2␦ ϫ 3␦ in the streamwise, transverse, and spanwise directions. The computational domain consists of periodic inflow/outflow boundaries, two solid wall boundaries, and ...

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“…In the authors' group, previous numerical investigations and most earlier experimental studies focused on round-ended U-bends, shown in Figure 1b, see Bo et al [3] and Iacovides et al [4]. These studies employed low-Reynolds-number models at both effective-viscosity and second-moment closure levels.…”

Section: Introductionmentioning

confidence: 99%

The computation of flow and heat transfer through an orthogonally rotating square‐ended U‐bend, using low‐Reynolds‐number models

Nikas

Iacovides²

2006

International Journal of Numerical Methods for Heat &Amp; Fluid Flow

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We present computations of heat and fluid flow through a square-ended U-bend that rotates about an axis normal to both the main flow direction and also the axis of curvature. Two-layer and low-Reynolds-number mathematical models of turbulence are used at effective-viscosity (EVM) level and also at second-moment-closure (DSM) level. Moreover, two length-scale correction terms to the dissipation rate of turbulence are used with the low-Re models, the original Yap term, and a differential form that does not require the wall distance (NYap). The resulting predictions are compared with available flow and heat transfer measurements of water. While the main flow features are well reproduced by all models, the development of the mean flow within and just after the bend is better reproduced by the low-Re models. Turbulence levels within the rotating U-bend are underpredicted, but DSM models produce a more realistic distribution. Along the leading side, all models overpredict heat transfer levels just after the bend. Along the trailing side, the heat transfer predictions of the low-Re DSM with the NYap, are close to the measurements.

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The computation of flow development through stationary and rotating U-ducts of strong curvature

Cited by 67 publications

References 10 publications

Application of pressure-sensitive paint to low-speed flow around a U-bend of strong curvature

Application of pressure-sensitive paint to low-speed flow around a U-bend of strong curvature

Direct numerical simulations of turbulent flow through a stationary and rotating infinite serpentine passage

The computation of flow and heat transfer through an orthogonally rotating square‐ended U‐bend, using low‐Reynolds‐number models

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