Evaporation Rate of a Liquid Layer Streamlined by Gas Flow in Minichannel

Paper presents the experimental results of mass evaporation rate from ethanol layer surface into a moving in parallel way air flow. Dependences of the mass evaporation rate on the gas velocity, temperature difference between gas and liquid layer, and liquid layer thickness were obtained. The assumption about the formation of the concentration boundary layer at the interface was made. It is found that with increasing the gas flow velocity the gradient of vapor concentration in the gas phase increases; as a result the evaporation rate rises. When changing the liquid layer thickness, the local maximum of evaporation rate was observed, but for 2 mm thickness layer two maxima were found. Probably, it is due the appearance of unstable structures on the liquid surface

Three-dimensional localized coherent structures of surface turbulence. III Experiment and model validation

The paper continues a series of publications devoted to the 3D nonlinear localized coherent structures on the surface of vertically falling liquid films. The work is primarily focussed on experimental investigations. We study: (i) instabilities and transitions leading to 3D coherent structures; (ii) characteristics of these structures. Some nonstationary effects are also studied numerically. Our experimental results, as well as the results of other investigators, are in a good agreement with our theoretical and numerical predictions.Comment: 42 pages, 15 figure

Nonlinear waves in bubbly liquids with consideration for viscosity and heat transfer

Nonlinear waves are studied in a mixture of liquid and gas bubbles. Influence of viscosity and heat transfer is taken into consideration on propagation of the pressure waves. Nonlinear evolution equations of the second and the third order for describing nonlinear waves in gas-liquid mixtures are derived. Exact solutions of these nonlinear evolution equations are found. Properties of nonlinear waves in a liquid with gas bubbles are discussed.Comment: Physics Letters A, Volume 374, Issues 19-20, Pages 2011-201

Evolving solitons in bubbly flows

At the end of the sixties, it was shown that pressure waves in a bubbly liquid obey the KdV equation, the nonlinear term coming from convective acceleration and the dispersive term from volume oscillations of the bubbles.\ud For a variableu, proportional to –p, wherep denotes pressure, the appropriate KdV equation can be casted in the formu t –6uu x +u xxx =0. The theory of this equation predicts that, under certain conditions, solitons evolve from an initial profileu(x,0). In particular, it can be shown that the numberN of those solitons can be found from solving the eigenvalue problem xx–u(x,0)=0, with(0)=1 and(0)=0.N is found from counting the zeros of the solution of this equation betweenx=0 andx=Q, say,Q being determined by the shape ofu(x,0). We took as an initial pressure profile a Shockwave, followed by an expansion wave. This can be realised in the laboratory and the problem, formulated above, can be solved exactly.\ud In this contribution the solution is outlined and it is shown from the experimental results that from the said initial disturbance, indeed solitons evolve in the predicated quantity.\u

Evaporation Rate of Distilled Water Drop on the Surface of Non-Ferrous Metals

We studied experimentally the evaporation process of distilled water drops on the surfaces of non-ferrous metals. Investigations were conducted on the experimental setup using a shadow optical system. The main elements of this system are the source of plane-parallel light and photographic camera. According to the contact diameter change during the evaporation, three stages have been determined (spreading, pinning, depinning). It has been found, that the dependence of evaporation rate on drop volume at low temperatures appear to be well fit by a power function

Experimental study of thermosyphon operation when cooling the condensation part by drop irrigation

The influence of drop irrigation of the condensation part on the thermosyphon operational mode was studied experimentally. The temperature and pressure fall was found in the internal space of the upper chamber after applying the liquid on the upper wall of the thermosyphon. The temperature difference along the height of vapor channel increases and the effective resistance decreases. When complete evaporation of liquid droplets from thermosyphon, it returns to the quasi-stationary mode of operation

Static contact angle versus volume of distilled water drop on micro patterned surfaces

Static contact angle was determined experimentally in the condition of wetting of polished and laser patterned surfaces of stainless steel substrates by distilled water drops with different volumes. In contrast with polished surface, the contact angle was found to depend on drop volume on micro patterned surfaces. In addition, the enhancement of both hydrophilic and hydrophobic properties was observed on laser patterned surfaces