BEGIN:VCALENDAR VERSION:2.0 PRODID:-//wp-events-plugin.com//6.6.4.4//EN TZID:Asia/Jerusalem X-WR-TIMEZONE:Asia/Jerusalem BEGIN:VEVENT UID:0-504@aerospace.technion.ac.il DTSTART;TZID=Asia/Jerusalem:20160120T163000 DTEND;TZID=Asia/Jerusalem:20160120T173000 DTSTAMP:20230603T192420Z URL:https://aerospace.technion.ac.il/events/spray-formation-by-homogeneous -flash-boiling/ SUMMARY:Spray Formation by Homogeneous Flash Boiling DESCRIPTION:Lecturer:Moti Levy\n Faculty:Department of Aerospace Engineerin g\n Institute:Technion – Israel Institute of Technology\n Location:Class room 165\, ground floor\, Library\, Aerospace Eng.\n Zoom: \n Abstract: \n Details: \n Injection systems are integrated in a variety of applications including fuel injection systems\, painting and coating processes\, medic al inhalers and more. In some applications\, and particularly in fuel inje ction systems\, the size and size distribution of the droplets are extreme ly important properties. For example\, in jet engines and internal combust ion engines the droplet's diameter affects the combustion performances\; s maller diameter usually means better combustion efficiency and reduced air pollution. Additionally\, since even small amount of large droplets incre ase the pollutants emission and reduce the efficiency\; the size distribut ion is also important. There are various injecting methods to produce a fi ne spray that contains small and uniform droplets\; in most of them there is a use of the fluid energy (plane or swirl atomizers)\, an added gas ene rgy (air blast and air assist atomizers) or mechanical energy (rotary or s linger atomizers) to shatter the liquid jet into fine spray. One of the mo re effective methods is to inject the fluid under suitable conditions to a ttain flash boiling atomization\; i.e. injecting a pure liquid or a mixtur e under initial conditions that ensure an evaporation of the liquid or at least one of the components in a mixture during the rapid depressurization caused by the expansion in the orifice. In a binary mixture for example\, a high vapor pressure propellant might be dissolved into a low vapor pres sure solvent in order to produce rapid evaporation of the propellant durin g the depressurization through the orifice\; the rapid evaporation of the propellant disintegrates the solvent into the desired fine spray.\nThe maj ority of the studies in this field deal with the most common case in which the bubbles are formed in preferred sites on the orifice walls or near co ntaminants (heterogeneous nucleation). Studies dealing with homogeneous nu cleation\, in which the bubbles are formed in the entire bulk\, are quite rare although finer spays are anticipated since the typical bubble formati on rate in the case of homogeneous regime is much higher. The current stud y deals with homogeneous flash boiling through a plane orifice. The spray properties of pure liquid and binary mixture were characterized experiment ally\, under variety injecting conditions (injecting temperature and press ure) and a wide range of propellant mass concentration. Also\, the border line between the two regimes was examined. Additionally\, since the major ity of the studies deal with the heterogeneous case\, there are neither su itable correlations nor analytical estimations for the typical droplets' d iameter under homogeneous nucleation regime. In the current work an analyt ical model has been developed to estimate the characteristic droplet diame ter in the spray for flash boiling atomization. One significant conclusion is that under homogeneous flash boiling\, remarkably small and uniform dr oplets are achieved\; therefore by using this relatively simple method ext remely fine sprays are obtained comparing to the other methods. CATEGORIES:Seminars LOCATION:Classroom 165\, ground floor\, Library\, Aerospace Eng. END:VEVENT BEGIN:VTIMEZONE TZID:Asia/Jerusalem X-LIC-LOCATION:Asia/Jerusalem BEGIN:STANDARD DTSTART:20151025T010000 TZOFFSETFROM:+0300 TZOFFSETTO:+0200 TZNAME:IST END:STANDARD END:VTIMEZONE END:VCALENDAR