Title: Numerical investigation on influence of focusing gas type on liquid micro-jet characteristics

Authors: Rizwan Zahoor; Saša Bajt; Božidar Šarler

Addresses: Laboratory for Fluid Dynamics and Thermodynamics, Faculty of Mechanical Engineering, University of Ljubljana, Aškerčeva 6, 1000 Ljubljana, Slovenia ' Photon Science, Deutsches Elektronen-Synchrotron DESY, Notkestraβe 85, 22607 Hamburg, Germany ' Laboratory for Fluid Dynamics and Thermodynamics, Faculty of Mechanical Engineering, University of Ljubljana, Aškerčeva 6, 1000 Ljubljana, Slovenia and Laboratory for Simulation of Materials and Processes, Institute of Metals and Technology, Lepi pot 11, 1000 Ljubljana, Slovenia

Abstract: Liquid micro-jets, produced from gas dynamic virtual nozzles (GDVNs), are used as sample carriers for interaction with X-ray beam in serial femtosecond crystallography (SFX). A numerical investigation of the effect of the focusing gas type on the liquid micro-jet properties (its length and thickness) is presented. The study complements our previous research on the influence of operating conditions and the nozzle geometry on GDVN performance. The influence of helium, argon, carbon dioxide and nitrogen gases (at a fixed mass flow rate of 1.6 × 104 mg/min) on focusing pure water jet (flow rate of 33 µl/min) is analysed. An experimentally validated numerical model, based on laminar two-phase Newtonian compressible flow with ideal gas assumption, finite volume method and volume of fluid interface tracking, is used. Helium is found to be the most suitable gas among the tested ones for producing thin, long and fast jets. The study provides a basis for the focusing gas selection in SFX experiments.

Keywords: gas dynamic virtual nozzle; GDVNs; focusing gas; micro-jet; compressible multiphase flow; finite volume method; volume of fluid; jetting; dripping.

DOI: 10.1504/IJHM.2018.092732

International Journal of Hydromechatronics, 2018 Vol.1 No.2, pp.222 - 237

Available online: 22 Jun 2018 *

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