Numerische Strömungssimulation an einer Niedergeschwindigkeits-Axialturbine unterschiedlichen Deckband-Abschirmungen des Laufrades

The numerical simulation of the flow through a low-speed turbine stage followed by a vane row is presented for two experimentally investigated shrouds of different weight and shape. The aerofoil-pressure distribution of the blades and vanes as well as the flow at the exit of the bladerow is compared in the experimentally and numerically obtained results. In addition to experimental data published earlier, numerical flow results are added, which had been inaccessible in the experiment. The choice of the turbulence model influences substantially the result of the numerical simulation for the flow leaving the rotor blade row. Furthermore the computational result shows the influence of the flow pattern in the labyrinth cavity on the power loss. The prediction of the static pressure decrease along the flow path through the seal across the cavities concludes this investigation.     

Friction factor correlation and pressure loss of single-phase flow inside herringbone microfin tubes

Pressure drop of single-phase turbulent flow inside herringbone microfin tubes of different fin dimensions has been measured experimentally to develop a general correlation of single-phase friction factor for the herringbone tubes. Water has been used as a working fluid and the mass flow rate has been varied from 0.03 to 0.2 kg/s, where the Reynolds number range is 10⁴ to 6.5 × 10⁴. Comparison of experimental data of the herringbone microfin tubes with those of helical microfin and smooth tubes shows that pressure drop of the herringbone tube is significantly higher than the helical and smooth tubes depending on the fin geometric parameters and mass velocity of the working fluid. Through semi-analytical approach and using the present experimental data, a new correlation of single-phase friction factor for the herringbone microfin tubes has been proposed incorporating the effects of fin geometric parameters. The proposed correlation can predict the experimental data within ±10%.     

Electromagnetic scattering from nonlinear anisotropic cylinders. I.Fundamental frequency

The solution of the problem of electromagnetic scattering of obliquely incident plane waves by homogeneous, nonlinear anisotropic cylindrical structures is obtained. The medium of the scatterer is characterized by Volterra-type integrals for the electric and magnetic flux density vectors D and B, respectively. The nonlinear problem is solved using the perturbation method. The effects of nonlinearities on the field properties both inside and outside the scatterer, together with the effect on the radar cross section, are investigated for the fundamental frequency components. To demonstrate the validity of the approach, the results obtained by the perturbation method are compared with those obtained using the plane wave representation method of D. Censor (1983), where the iteration method is used to solve the resulting dispersion equation. The results are in very good agreement in both amplitude and phase of the fields for the case of very weak nonlinearity. When the relative magnitude of the nonlinear component of the permittivity is increased, the iteration method shows a faster divergence of the phase from the linear phase     

Erratum to: Conductivity Sensors Based System Development and Application to Investigate the Interfacial Behaviour between Supersonic Steam Jet and Water

Instruments and Experimental Techniques - An Erratum to this paper has been published: https://doi.org/10.1134/S0020441221050249     

Effect of Lateral Water Surface Profile on Side Weir Discharge

The average water surface slope in the lateral direction is taken into account as a local parameter ψ to study flow over a side weir. It was later shown that for smaller side weir lengths and side weir portions with no entrance and exit transition effects, ψ can be obtained from a numerical integral and also from the measurements of water surface elevations in the lateral direction. The effect of elemental weir length was further determined. Dividing the weir length into smaller computational segments has the effect of lowering the water surface to approach the measured profile, the downstream ends being coincident. The model was verified using experimental data.     

Formulation and Characterization of Novel Nanostructured Lipid Carriers with Photoprotective Properties Made from Carnauba Wax,Beeswax, Pumpkin Seed Oil,and UV Filters

Pumpkin seed oil (PSO) with carnauba wax and beeswax was used to develop nanostructured lipid carriers (NLC) loaded with a UV filter, Uvinul® A Plus B. The aims of the study were to optimize the concentration of PSO to develop a stable NLC formulation, determine storage stability of the NLC with and without PSO, and the synergistic effect of PSO-NLC with UV filter for photoprotective properties. The physical properties of NLC were optimized based on the mean particle size, polydispersity index, and storage stability. The optimized NLC consisted 10% lipid phase (3.5% carnauba wax, 3.5% beeswax, and 3.0% PSO) and 90% aqueous phase. After optimization, Uvinul® A Plus B was added in the optimized PSO-NLC to produce a photoprotective formulation. Uvinul® A Plus B consisted of both UVA (Diethylamino Hydroxybenzoyl Hexyl Benzoate) and UVB (Ethylhexyl Methoxycinnamate) filters. The NLC produced with PSO and Uvinul® A Plus B had mean particle size of 135 ± 2 nm and showed good physical stability under storage time. Besides that, the NLC produced also proven to have positive effect in enhancing the entrapment efficiency and drug loading, which were 82.86 ± 0.15% and 55.41 ± 0.04%, respectively, and showed sun protection factor value of 16.61 ± 3.45. The results indicated the presence of synergistic effect among the PSO-NLC with Uvinul® A Plus B.     

LOW TEMPERATURE OXIDATION OF LOW RANK COALS

The low temperature oxidation of a Montana subbituminous coal was investigated using round bottom 100 ml flasks in constant temperature baths. The experiments were carried out in normal and oxygen enriched air at 30°C, 45°C and 70°C with particle sizes ranging from 4 mesh to 100 mesh. Periodic analysis of gas samples from the flasks provided the rate data. The reactivity of the as received coal was compared with that of the same coal dried (i) in high pressure steam and (ii) in hot water

A rate equation has been proposed incorporating the effects of oxygen diffusion and surface reaction. For higher oxygen concentration and smaller particle sizes, the zero order surface reaction was found to be controlling. The temperature dependency of the reaction rate was found to be well represented by the Arrhenius equation. The activation energy varied slightly under various conditions between 15 to 20 kca)/g mole

The reactivity of the hot water dried coal was found to be similar to that of the as received coal. Steam dried coal however, was found to be much less reactive.