www.tjprc.org SCOPUS Indexed Journal editor@tjprc.org FORMATION OF GAS BUBBLES IN A STAGNANT LIQUID EXAMINED FOR THE TECHNOLOGICAL APPLICATION OF METAL FOAM SHEHAB ATTIA 1 , KAREL FRANA 2 & IVA NOVA 3 1,2 Department of Energetics, Technical University of Liberec, Czech Republic 3 Department of Engineering Technology – Materials Science, Technical University of Liberec, Czech Republic ABSTRACT A study of different shapes of gas bubbles rising in stagnant liquid experimentally. A testing facility with the high-speed camera was designed. The results obtained are presented in terms of dimensionless parameters i. e. Reynold’s, Morton’s and Eötvös. Factors varied to test their dependencies such as nozzle diameter (3 – 5 mm), rate of flow rate (15 and 130 l/h), viscosity, surface tension, and density were changed in order to see their effect on the shape of the bubble, its velocity in the liquid, surface tension force, drag force and buoyancy force. In order to vary such parameters, a water-ethanol mixture was used in the tank. Results showed at surface tension valued at 32 [N/m] it was not possible to trap air bubbles under the surface for the application of creating Foam, while 72 [N/m] it was possible, while for the tested flow rates most of Eötvös values were below one, which indicates that surface tension force dominates shape of the bubble when compared to gravitational force influence. KEYWORDS: Bubble Shapes, Metal Foam, Eotvos, Viscosity, Speed Camera & Flowrates Received: Dec 21, 2018; Accepted: Jan 11, 2019; Published: Feb 14, 2019; Paper Id.: IJMPERDAPR201916 INTRODUCTION Metal foam has been gaining popularity recently, Market demands have pursued new material solutions catering for a low specific weight, porosity, high stiffness, and impact absorption, as stated by V. C. Srivastava (2006) [1]. Which makes using metal foam attractive for modern industry manufacturers, Potential uses in light-weight applications including automotive, aircraft, and heat exchangers, accelerated such research from a niche solution to a currently highly commercialized utilization as surveyed by Bhatnagar (2017) [2] The word “foam” has been used in many different connotations, thus there is a need to define it. Foam is the product of gas bubbles locked inside a liquid by the force of surface tension of that liquid. Yet as Banhart (2001) defined it, for most industrial applications the foam used would be Solid foam that has the cellular form [3]. could be used to clarify the different types of phase mixtures and the common nomenclature describing such mixtures. Several ways are used to manufacture metal foam, it’s in continuous increase according to market trends studied by Seeliger (2012) due to market demand for lower specific weight with high stiffness for aluminum foam sandwich [4], or ability to absorb sounds in acoustic applications due to its porous structure as stated by Jorge P. (July 2010) [5]. One main process to manufacture the foam is by gas injection, in which the metal foams are directly fabricated by injecting a pressurized gas in the molten metal, for this approach several factors are considered influencing for the process to be carried out successfully, for example, the viscosity of the molten metal, viscosity pressure of gas injected. The viscosity of the metal is usually controlled by adding some salt or powdered Original Article International Journal of Mechanical and Production Engineering Research and Development (IJMPERD) ISSN (P): 2249-6890; ISSN (E): 2249-8001 Vol. 9, Issue 2, Apr 2019, 171-182 © TJPRC Pvt. Ltd.