Velocity Profiles in a Cylindrical Liquid Jet by Reconstructed Velocimetry

An experimental setup and a simple reconstruction method are presented to measure velocity fields inside slightly tapering cylindrical liquid jets traveling through still air. Particle image velocimetry algorithms are used to calculate velocity fields from high speed images of jets of transparent liquid containing seed particles. An inner central plane is illuminated by a laser sheet pointed at the center of the jet and visualized through the jet by a high speed camera. Optical distortions produced by the shape of the jet and the difference between the refractive index of the fluid and the surrounding air are corrected by using a ray tracing method. The effect of the jet speed on the velocity fields is investigated at four jet speeds. The relaxation rate for the velocity profile downstream of the nozzle exit is reasonably consistent with theoretical expectations for the low Reynolds numbers and the fluid used, although the velocity profiles are considerably flatter than expected.This work was sponsored by EPSRC grant number RG5560

Aerodynamic effects in ink-jet printing on a moving web

This work was sponsored by EPSRC grant number RG5560

Dependence of drop speed on nozzle diameter, viscosity and drive amplitude in drop-on-demand ink-jet printing

Results of recent experiments and numerical simulations are presented, which have been used to establish empirical rules for the dependence of drop speed on nozzle diameter and drive amplitude for Newtonian and non-Newtonian fluids printed with a range of different ink-jet print-head technologies. Experiments were carried out with Xaar, MicroFab and Spectra Dimatix print heads and with solutions of polystyrene in diethyl phthalate as model fluids. These results are compared with predictions from recent numerical codes developed by collaborators in the University of Leeds, and from simple models for drop-on-demand fluid jetting resulting from physical law

How PEDOT:PSS solutions produce satellite-free inkjets

This work is sponsored by EPSRC grant number RG5560

Jetted mixtures of particle suspensions and resins

This is the author accepted manuscript. The final version is available from AIP at http://scitation.aip.org/content/aip/journal/pof2/26/10/10.1063/1.4897238.Drop-on-demand (DoD) ink-jetting of hard particle suspensions with volume fraction Φ ~ 0.25 has been surveyed using 1000 ultra-high speed videos as a function of particle size (d90 = 0.8-3.6 µm), with added 2 wt% acrylic (250 kDa) or 0.5 wt% cellulose (370 kDa) resin, and also compared with Newtonian analogues. Jet break-off times from 80 µm diameter nozzles were insensitive (120±10 µs) to particle size, and resin jet break-off times were not significantly altered by > 30 wt% added particles. Different particle size grades can be jetted equally well in practice, while resin content effectively controls DoD break-off times

Ultra-high speed particle image velocimetry on drop-on-demand jetting

Se estudian los conceptos claves de fortuna, virtù y gloria, con elobjeto de buscar algunas aclaraciones sobre el problema de larelación entre moral y política en Maquiavelo. La virtù maquiavelianaincluye, sin duda, múltiples componentes de energía, talento,pero no está completamente exenta de elementos morales. Delconcepto de fortuna podemos extraer una serie de criterios parala acción política que forman parte de la virtù maquiaveliana, lacual, si bien se aleja de la moral cristiana vigente en su tiempo, lesitúa dentro de una moral republicana. Del examen del conceptode gloria descubrimos cómo la gloria es recompensa de la virtù,pero no se reconoce a cualquier político que tiene éxito en susempresas, sino solo a quien salva a la patria y lo hace con mediosbenignos.</jats:p