NATURAL-CONVECTION FROM HORIZONTAL WIRES TO VISCOELASTIC FLUIDS

Natural convection heat transfer from horizontal wires of three different diameters (0. 0254, 0. 0508, 0. 0826 cm) to a pool of viscoelastic liquid was studied. Aqueous solutions of Natrosol and Polyox constituted the viscoelastic test fluids. The experimental Nusselt numbers were found to agree with the correlations recommended by Fand and Bruckner for Newtonian fluids if the zero shear rate viscosity is used in the Rayleigh and Prandtl numbers

Electrical and optical properties of Ti doped ZnO films grown on glass substrate by atomic layer deposition

Titanium doped zinc oxide (Ti doped ZnO) films were prepared by atomic layer deposition methods at a deposition temperature of 200 °C. The Ti content in Ti doped ZnO films was varied from 5.08 at.% to 15.02 at.%. X-ray diffraction results indicated that the crystallinity of the Ti doped ZnO films had degraded with increasing Ti content. Transmission electron microscopy was used to investigate the microstructural evolution of the Ti doped ZnO films, showing that both the grain size and crystallinity reduced with increasing Ti content. The electrical resistivity of the Ti doped ZnO films showed a minimum value of 1.6 × 10-3 Ω cm with the Ti content of 6.20 at.%. Furthermore, the Ti doped ZnO films exhibited excellent transmittance. © 2014 Elsevier Ltd.

Combined aerodynamic and electrostatic atomization of dielectric liquid jets

The electrical and atomization performance of a plane-plane charge injection atomizer using a dielectric liquid, and operating at pump pressures ranging from 15 to 35 bar corresponding to injection velocities of up to 50m/s, is explored via low current electrical measurements, spray imaging and phase Doppler anemometry (PDA). The work is aimed at understanding the contribution of electrostatic charging relevant to typical higher pressure fuel injection systems such as those employed in the aeronautical, automotive and marine sectors. Results show that mean specific charge increases with injection velocity significantly. The effect of electrostatic charge is advantageous at the 15-35 bar range and an arithmetic mean diameter D10 as low as 0.2d is achievable in the spray core and lower still in the periphery where d is the orifice diameter. Using the data available from this higher pressure system and from previous high Reynolds number systems [1], the promotion of primary atomization has been analyzed by examining the effect that charge has on liquid jet surface and liquid jet bulk instability. The results suggest that for the low charge density Qv~2C/m3 cases under consideration here, a significant increase in primary atomization is observed due to a combination of electrical and aerodynamic forces acting on the jet surface, attributed to the significantly higher jet Weber number (Wej) when compared to low injection pressure cases. Analysis of Sauter mean diameter (SMD) results show that for jets with elevated specific charge density of the order QV~6C/m3, the jet creates droplets that a conventional turbulent jet would, but with a significantly lower power requirement. This suggests that “turbulent” primary atomization, the turbulence being induced by electrical forces, may be achieved under injection pressures that would produce laminar jets