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Kulik V.M.,RAS Kutateladze Institute of Thermophysics
International Journal of Heat and Fluid Flow | Year: 2012

The rate and amplitude of compliant coating deformation by turbulent pressure pulsations were calculated. Complex compliance determined by a 2D model has two components: along and across the coating. Dependence of the components of dimensionless compliance on the ratio between wavelength λ and coating thickness H was determined for 0.3 < λ/H< 30 and dependence of these components on the ratio of flow velocity V to shear velocity Ct0 was determined for 0.1

Chinnov E.A.,RAS Kutateladze Institute of Thermophysics
Technical Physics Letters | Year: 2012

The evolution of three-dimensional (3D) waves into thermocapillary-wave structures in a locally heated water film flowing down a vertical plate has been experimentally studied. The interaction of hydrodynamic perturbations with thermocapillary instabilities was monitored using a high-speed high-resolution IR imager. The existence of thermocapillary structures has been observed for the first time at high Reynolds numbers (Re = 150) in regime A, which is characterized by high temperature gradients on the film surface and a definite value of the "most dangerous" wavelength of instability that arises when the heat flux density exceeds a certain threshold. It is established that structures periodically appear in which the distance between temperature maxima is much shorter than that observed before. As the heat flux density is increased, the thermal entry length exhibits a sharp drop when thermocapillary instabilities arise in the vicinity of the upper edge of the heater. © 2012 Pleiades Publishing, Ltd.

Misyura S.Ya.,RAS Kutateladze Institute of Thermophysics
International Journal of Heat and Mass Transfer | Year: 2014

Dynamics of nucleate boiling in droplets of bidistillate on different wall surfaces was studied experimentally. These experiments were carried out on the rough copper and on the polished surface with plasma spraying of a golden film. The surface state was investigated by an electron microscope and 3D image processing software. Characteristic microroughness responsible for minimal superheating at nucleate boiling was determined. Heat transfer on the polished surface was significantly worse than on the rough wall. Thermal measurements were performed by means of a multiple increase in thermal imaging. When boiling on the polished surface, the self-organized ordered structures are formed there. © 2013 Elsevier Ltd. All rights reserved.

Chinnov E.A.,RAS Kutateladze Institute of Thermophysics
International Journal of Heat and Mass Transfer | Year: 2014

The temperature distributions and wave characteristics of the water film flowing down a vertical plate with a heater of 100 × 150 mm at Re = 150, 300, 500 are studied. The field of film thicknesses at different heat flux values was measured using the fluorescence method. The temperature field on the film surface was measured by an infrared scanner. The experimental data were obtained for variations in temperature over the liquid film surface with time during the propagation of waves. Thermocapillary forces that arise on heating lead to the formation of rivulets separated by thin layer troughs, with three-dimensional (3D) waves propagating over the crests of rivulets. Averaging of measurements allowed the values of the transverse film deformation and distance between the rivulets to be determined. In the interrivulet zone Marangoni number increases with a rise of the heat flux. The amplitudes of 3D waves in a water film flowing down a vertical heated plate have been measured. The film thickness and 3D wave amplitudes on the heater grow with increasing heat flux and distance downstream the flow, but the relative wave amplitude remains unchanged. In the heated regions between rivulets, the relative amplitude of waves increases with decreasing average thickness (or local Reynolds number). Analysis of results obtained for large Reynolds numbers showed that the relative amplitudes of waves in the regions between rivulets at high heat fluxes are much greater than those for small Reynolds numbers and in isothermal falling films. Two mechanisms of thermocapillary forces influence on the motion of the wavy liquid film are marked. For the first time, the exhibition of such a strong thermocapillary effects is revealed in the heated liquid film at high Reynolds numbers. © 2013 Elsevier Ltd. All rights reserved.

Chinnov E.A.,RAS Kutateladze Institute of Thermophysics
Technical Physics Letters | Year: 2015

Dynamics of temperature fluctuations on the surface of a vertically falling heated film of water are analyzed at Reynolds number 500 under conditions of motion of developed three-dimensional waves. It is shown that the high-frequency component of temperature fluctuations decays as long as the film moves in the heater bottom part. Some temperature perturbations are carried away into the rivulet region due to transverse thermocapillary forces. At high densities of heat fluxes, only the maximum temperature fluctuations generated by the largest waves reach the heater bottom. In this case, the averaged integral energy of temperature fluctuations in the interrivulet region is reduced. © 2015, Pleiades Publishing, Ltd.

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