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Séminaire Y. Tarawa

9 septembre 2016

Viscous liquid jets induced by an impulsive force and effects of cavitation

Séminaire Yoshiyuki Tarawa

(Tokyo University of Agriculture and Technology - Mechanical Systems Engineering)

Mardi 20 septembre à 15 h 00

Salle Castex Rez de chaussée

Abstract :

A liquid jet is of great importance for various important applications such as ink-jet printers. However, most of the existing printers are not able to eject highly-viscous liquids, the viscosities of which are higher than approximately 20 cSt. This severe limitation leads to crucial problems for printers such as blurring and color-dulling. In addition, highly-viscous liquids have various functionalities such as adherence and conductivity. Thus the development of a method for generating highly-viscous microjets opens new doors for next-generation technologies.
In this presentation we introduce a novel system for generating a highly-viscous microjet with up to 500 cSt. The structure of the device is quite simple as described below : We produce a micro-jet inside a wettable-thin tube that is partially inserted in a liquid bath. We keep the gas-liquid interface inside the tube much deeper than that outside of the tube. We then add an impulsive force at the bottom of the liquid container. The addition of an impulsive force results in the significant acceleration of the liquid inside the tube. This simple yet innovative setup enables us to generate highly-viscous jets.
We lead a physical model based on a pressure impulse approach and investigate effects of cavitation on the jets. Furthermore we conduct numerical simulations. Results are found to agree with the proposed model. We believe that the development of this device is a starting point for next-generation technologies such as highly-viscous ink-jet printers including printed electronics and 3D printers, and needle-free injection devices for low-invasive medical treatments.