Search

Your search keyword '"Glavatskih, Sergei"' showing total 250 results
Start Over Author "Glavatskih, Sergei"
250 results on '"Glavatskih, Sergei"'

11. Acceleration of diffusion in ethylammonium nitrate ionic liquid confined between parallel glass plates

Author

Filippov, Andrei, Gnezdilov, Oleg I., Hjalmarsson, Nicklas, Antzutkin, Oleg N., Glavatskih, Sergei, Furó, Istvan, and Rutland, Mark W.

Subjects
Physics - Chemical Physics, Condensed Matter - Soft Condensed Matter
Abstract

The bulk self diffusion of the ethylammonium cation and the nitrate anion can both be described by respective single diffusion coefficients. Diffusion of the anion is 1.7 times higher than that of the cation. This indicates no tight association of the ions in the ionic liquid. For the ethylammonium cation confined between glass plates the effective diffusion coefficient along, as well as normal to the confining glass plates is higher by a factor of 1.86 as compared to that in the bulk. The same time, NMR T2 relaxation of protons of NH3 group of the EA cation is faster by a factor of 22 than that in bulk. 2H NMR spectra of selectively labeled CH2 and CH3 groups of EA do not demonstrate any ordering of the EA between the glass plates. We suggested that these data favor a model where a bulk isotropic sponge like structure of EAN is saved in the confinement, but sizes of connecting channels increases. Those leads to faster translational diffusion and faster exchange processes of protons of NH3 group, in comparison with the bulk., Comment: 11 pages, 5 figures, 1 table

Published
2017
Full Text
View/download PDF

32. Wear in wind turbine pitch bearings - A comparative design study

Author

Schwack, Fabian, Halmos, Fabian, Stammler, Matthias, Poll, Gerhard, Glavatskih, Sergei, and Publica

Abstract

We tested two types of ball bearings with an outer diameter of 750 mm to learn more about the challenges of oscillating motions for pitch bearings. The experimental conditions are derived from aero-elastic simulations, long-term wind speed measurements and a scaling method that considers loads and pitch angles. As a result, the parameters relevant for pitch bearings are represented appropriately, and the findings are transferable to other bearing sizes. For the tested parameter sets, severe wear occurred for over 90% of the exposed contact areas after 12 500 oscillating cycles. Decreasing the number of cycles to 1250 leads to a mix of exposed areas with 13% severe wear, 32% mild wear and 55% no wear, with no apparent pattern. The results demonstrate that a comparatively small amount of consecutive cycles can lead to severe wear. A new type of bearing tested showed less wear for the selected operating conditions.

Published
2022

40. Electro-responsivity of ionic liquid boundary layers in a polar solvent revealed by neutron reflectance.

Author

Pilkington, Georgia A., Harris, Kathryn, Bergendal, Erik, Reddy, Akepati Bhaskar, Palsson, Gunnar K., Vorobiev, Alexei, Antzutkin, Oleg. N., Glavatskih, Sergei, and Rutland, Mark W.

Subjects
IONIC liquids, BOUNDARY layer (Aerodynamics), NEUTRON reflectivity, POLAR solvent analysis, MEASUREMENT of viscosity, ION scattering
Abstract

Using neutron reflectivity, the electro-responsive structuring of the non-halogenated ionic liquid (IL) trihexyl(tetradecyl)phosphonium-bis(mandelato)borate, [P6,6,6,14][BMB], has been studied at a gold electrode surface in a polar solvent. For a 20% w/w IL mixture, contrast matched to the gold surface, distinct Kiessig fringes were observed for all potentials studied, indicative of a boundary layer of different composition to that of the bulk IL-solvent mixture. With applied potential, the amplitudes of the fringes from the gold-boundary layer interface varied systematically. These changes are attributable to the differing ratios of cations and anions in the boundary layer, leading to a greater or diminished contrast with the gold electrode, depending on the individual ion scattering length densities. Such electro-responsive changes were also evident in the reflectivities measured for the pure IL and a less concentrated (5% w/w) IL-solvent mixture at the same applied potentials, but gave rise to less pronounced changes. These measurements, therefore, demonstrate the enhanced sensitivity achieved by contrast matching the bulk solution and that the structure of the IL boundary layers formed in mixtures is strongly influenced by the bulk concentration. Together these results represent an important step in characterising IL boundary layers in IL-solvent mixtures and provide clear evidence of electro-responsive structuring of IL ions in their solutions with applied potential. [ABSTRACT FROM AUTHOR]

Published
2018
Full Text
View/download PDF

41. Wear in wind turbine pitch bearings—A comparative design study

Author

Schwack, Fabian, Halmos, Fabian, Stammler, Matthias, Poll, Gerhard, and Glavatskih, Sergei

Subjects
Blade bearing, downscaled experiments, Bearing designs, Experimental conditions, Oscillating motion, Severe wears, individual pitch control, Dewey Decimal Classification::600 | Technik::620 | Ingenieurwissenschaften und Maschinenbau, Wind, Turbomachine blades, Design studies, Downscaled experiment, Outer diameters, Wear of materials, Learn+, Wind turbines, bearing design, Wind power, ddc:620
Abstract

We tested two types of ball bearings with an outer diameter of 750 mm to learn more about the challenges of oscillating motions for pitch bearings. The experimental conditions are derived from aero-elastic simulations, long-term wind speed measurements and a scaling method that considers loads and pitch angles. As a result, the parameters relevant for pitch bearings are represented appropriately, and the findings are transferable to other bearing sizes. For the tested parameter sets, severe wear occurred for over 90% of the exposed contact areas after 12 500 oscillating cycles. Decreasing the number of cycles to 1250 leads to a mix of exposed areas with 13% severe wear, 32% mild wear and 55% no wear, with no apparent pattern. The results demonstrate that a comparatively small amount of consecutive cycles can lead to severe wear. A new type of bearing tested showed less wear for the selected operating conditions. © 2021 The Authors. Wind Energy published by John Wiley & Sons Ltd.

Published
2021
Full Text
View/download PDF

47. Pressure buildup mechanism in a textured inlet of a hydrodynamic contact

Author

Cupillard, Samuel, Cervantes, Michel J., and Glavatskih, Sergei

Subjects
Surfaces -- Properties, Surfaces (Technology) -- Properties, Hydrodynamics -- Research, Bearings (Machinery) -- Mechanical properties, Pressure -- Measurement, Pressure -- Methods, Hydrofoil boats -- Hydrodynamics, Hydrofoil boats -- Research, Science and technology
Abstract

A flow analysis is carried out for an inclined slider bearing with the aim of showing the governing mechanism at conditions where an optimum in load carrying capacity is achieved. The effects of surface texture on pressure buildup and load carrying capacity are explained for a textured slider bearing geometry. Numerical simulations are performed for laminar, steady, and isothermal flows. The energy transferred to the fluid from the moving wall is converted into pressure in the initial part of the converging contact and into losses in the second part. The convergence ratio can be increased, in order to get the greatest pressure gradient, until the limiting value where flow recirculation begins to occur. The texture appears to achieve its maximum efficiency when its depth is such that the velocity profile is stretched at its maximum extent without incurring incoming recirculating flow. The wall profile shape controlling the velocity profile can be optimized for many hydrodynamic contacts. Keywords: convergent surface, texture, pressure buildup, recirculation

Published
2008

48. Diffusion of Ions in Phosphonium Orthoborate Ionic Liquids Studied by 1H and 11B Pulsed Field Gradient NMR

Author

Filippov, Andrei, Munavirov, Bulat, Glavatskih, Sergei, Shah, Faiz Ullah, and Antzutkin, Oleg N.

Subjects
DYNAMICS, B-11 NMR diffusion, MIXTURES, RELAXATION, ion dynamics, General Chemistry, 11B NMR diffusion, TRANSPORT, ionic liquids, pulsed-field-gradient NMR diffusometry, Chemistry, nuclear magnetic resonance, SELF-DIFFUSION, Original Research
Abstract

Non-halogenated boron-based ionic liquids (ILs) composed of phosphonium cations and chelated orthoborate anions have high hydrolytic stability, low melting point and exceptional properties for various applications. This study is focused on ILs with the same type of cation, trihexyltetradecylphosphonium ([P-6,P-6,P-6,P-14](+)), and two orthoborate anions, such as bis(salicylato)borate ([BScB](-)) and bis(oxalato)borate ([BOB](-)). We compare the results of this study with our previous studies on ILs with bis(mandelato)borate ([BMB](-)) and a variety of different cations (tetraalkylphosphonium, dialkylpyrrolidinium and dialkylimidazolium). The ion dynamics and phase behavior of these ILs is studied using H-1 and B-11 pulsed-field-gradient (PFG) NMR. PFG NMR is demonstrated to be a useful tool to elucidate the dynamics of ions in this class of phosphonium orthoborate ILs. In particular, the applicability of B-11 PFG NMR for studying anions without H-1, such as [BOB](-), and the limitations of this technique to measure self-diffusion of ions in ILs are demonstrated and discussed in detail for the first time.

Published
2020

Catalog

Books, media, physical & digital resources
See catalog results