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- Chernoray, Valery, 1975, et al.
(författare)
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Experimental study of multiphase flow in a model gearbox
- 2011
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Ingår i: Multiphase Flow VI, Sixth International Conference on Computational and Experimental Methods in Multiphase and Complex Flow, WIT Transactions on Engineering Sciences. - 1743-3533. - 9781845645182 ; 70, s. 153-164
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Konferensbidrag (refereegranskat)abstract
- This study concerns dynamics of a two-phase flow around a rotating solid body. Under consideration is a model of a gear wheel in a gearbox which rotates and is partially submerged in oil. The flow of interest is complex and involves effects of free surface dynamics, rotation, and formation of bubbles and drops. Occurring flow regimes include laminar, transitional and turbulent. The major focus of the investigation is on details of the developed flow, and the purpose is validation of numerical methods developed for design and optimization of such components. Current experiments are performed in a test rig which is modelling a generic simplified gearbox with a single isolated rotating wheel. The flow measurements are carried out by using particle image velocimetry (PIV) and the test rig is specially designed for this purpose with the optical access maximized. The flow similarity with respect to a real gearbox is fully maintained and the working fluid is a transparent mineral oil. The PIV measurements are performed at four different rotation speeds for two different wheel configurations in order to cover a spectrum of operational conditions needed for numerical modelling. The emphasis is on the result of experiments on a smooth wheel. The measurements are providing velocity distribution around the wheel and details on bubble and drop distribution.
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- Chernoray, Valery, 1975, et al.
(författare)
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Flow pass a rotating cylinder with end disk: PIV measurements and RANS computations
- 2012
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Ingår i: EFMC 2012, European Fluid Mechanics Conference.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Because of the increasing attention to fuel consumption and anticipated legislation, the Flettner rotor has attained renewed interest recently as an auxiliary ship propulsion device. To improve the understanding of the flow involved, the flow structure around a Flettner rotor is studied by both three-dimensional PIV measurements and RANS simulation for a case with Re equal to 2.0 104, based on the inlet velocity (U) and cylinder diameter (D) for the aspect ratio 6, and spin ratio equal to 4.3.A test model of Flettner rotor is installed in the wind tunnel. A thin polymethyl methacrylate disk with diameter of 2D is installed at the top the cylinder following Prandtl1. The horizontal measurement plane is perpendicular to the axis of cylinder as shown in figure 1. To build up the fully three dimensional measurement data, 62 sequences of two-dimensional three components measurements at different axial position are made. The steady RANS simulation is done with SST k –ω model. The geometry of Fletter rotor as in wind tunnel measurement is used. The size of computation domain is chosen according to the one in the literature2. The domain is discretized by a hexahedral mesh, with the carefully designed boundary layer mesh around the rotor (see Figure 1). A uniform velocity inlet boundary condition is used for the inlet and slip boundary condition is chosen for the sides.Both PIV measurement and CFD show similar vortices around the rotor but with some differences as indicated in Figure 2: the simulation cannot well predict the flow at the middle plane, which important for the lift prediction. Further verification and validation will be done with force measurement.
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- Chernoray, Valery, 1975, et al.
(författare)
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Instability of a swept-wing boundary layer modulated by stationary flow perturbations
- 2013
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Ingår i: Visualization of Mechanical Processes: An International Online Journal. - 2152-209X. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- A collection of illustrations of swept-wing boundary layer secondary instability at low subsonic flow velocities is presented in this paper. The experimental results, obtained by hot-wire "visualization," provide detailed insight into the spatio-temporal structure and evolution of oscillations in the three-dimensional laminar boundary layer disturbed by longitudinal vortices and streaky structures.
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- Chernoray, Valery, 1975, et al.
(författare)
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Measurements and Prediction of Laminar-Turbulent Transition at High Free-Stream Turbulence and Pressure Gradients
- 2012
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Ingår i: 28th Congress of the International Council of the Aeronautical Sciences 2012, ICAS 2012. ; 2, s. 1119-1128
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Konferensbidrag (refereegranskat)abstract
- This paper is focused on measurements and prediction of laminar-turbulent transition at high free-stream turbulence in boundary layers of airfoil geometries with external pressure gradient changeover. Experimental and numerical study is performed for a number of flow cases covering a range of flow Reynolds numbers, turbulence intensities and pressure gradient distributions. The flow parameters in experiments and computations are typical for turbomachinery applications and main motivation of current study is validation of transition models which can be used for transition prediction in such engineering applications. In current work the experimental data are used to validate a transition model by Langtry and Menter which showed good agreement with experiments for all test cases.
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- Chernoray, Valery, 1975
(författare)
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Prediction of Laminar-Turbulent Transition on an Airfoil at High Level of Free-Stream Turbulence
- 2013
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Ingår i: Proc of EUCASS Conf..
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Konferensbidrag (refereegranskat)abstract
- Prediction of laminar-turbulent transition at high level of free-stream turbulence in boundary layers of airfoil geometries with external pressure gradient changeover is in focus. The aim is a validation of a transition model for transition prediction in turbomachinery applications. Numerical simulations have been performed by using a transition model by Langtry and Menter for a number of different cases of pressure gradient, at Reynolds number-range, based on the airfoil chord, 50 000 ≤ Re ≤ 500 000 and free-stream turbulence intensities 2 % and 4 %. The validation of the computational results against the experimental data showed good performance of used turbulence model for all test cases.
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- Chernoray, Valery, 1975, et al.
(författare)
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Secondary instability of a swept-wing boundary layer disturbed by controlled roughness elements
- 2010
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Ingår i: Journal of Visualization. - : Springer Science and Business Media LLC. - 1343-8875 .- 1386-6478 .- 1875-8975. ; 13:3, s. 251-256
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Tidskriftsartikel (refereegranskat)abstract
- Wind-tunnel data on velocity perturbations evolving in a laminar swept-wing flow under low subsonic conditions are reported. The focus of the present experiments are secondary disturbances of the boundary layer which is modulated by stationary streamwise vortices. Both the stationary vortices and the secondary oscillations of interest are generated in a controlled manner. The experimental data are obtained through hot-wire measurements. Thus, evolution of the vortices, either isolated or interacting with each other, is reconstructed in detail. As is found, the secondary disturbances, initiating the laminar-flow breakdown, are strongly affected by configuration of the stationary boundary-layer perturbation that may have an implication to laminar-turbulent transition control.
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