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UID:0-223@aerospace.technion.ac.il

DTSTART;TZID=Asia/Jerusalem:20230419T133000

DTEND;TZID=Asia/Jerusalem:20230419T143000

DTSTAMP:20230416T103900Z

URL:https://aerospace.technion.ac.il/events/shape-development-and-stabilit
 y-of-a-supercavitation-bubble/

SUMMARY:Shape\, Development and Stability of a Supercavitation Bubble
DESCRIPTION:Lecturer:Lotan Arad Ludar\n Faculty:Department of Aerospace Eng
 ineering\n Institute:Technion – Israel Institute of Technology\n Locatio
 n:Meeting Room 203 - Rocket Propulsion Center\n Zoom: https://technion.zoo
 m.us/j/97346140543\n Abstract: The Supercavitation phenomenon has been stu
 died for decades utilizing the nature vaporization of the water surroundin
 g high speed underwater vehicles to reduce the drag acting on the supercav
 itational bodies. Yet\, many questions and problems remained open and unso
 lved regarding the process and the characteristics of the bubble and the s
 upercavitational regime. Understanding the creation and development\, the 
 shape\, and the stability of a supercavitation bubble is essential for the
  design of supercavitational underwater vehicles and applications and it i
 s at the center of this study.\n\nTo enhance understanding of the supercav
 itation bubble shape and structure\, two series of experiments have been c
 onducted in two advanced systems: one resemble a duct flow\, and the other
  a free-surface flow. The experiments have been applied on cylindrical sle
 nder bodies in a uniform flow of water\, in different flow speeds. A compa
 rison of supercavitation bubbles created on bodies with different nose geo
 metries (i.e.\, cavitators)\, has been made. The comparison was referred t
 o the conditions of the bubbles’ creation and collapse\, and also their 
 shape and development.\n\nAlso theoretical efforts have been made\, in ord
 er to examine the supercavitation bubble geometry. An analytical model of 
 an axisymmetric supercavitation bubble in a viscous flow has been made.  
 The viscosity of the flow has typically been neglected in research on supe
 rcavitational flows\, using non-viscous potential flows. However\, for som
 e situations and conditions\, the viscosity was found to be significant an
 d crucial for the bubble geometry and formation\, especially at the superc
 avitation bubble detachment point. The results of the analyses show the ch
 ange of the bubble formation from past models due to the viscosity\, and o
 ffer a more accurate description of the bubble geometry.\n\nAnother theore
 tical examination conducted in this study\, aimed at learning about the pr
 essure field of the supercavitation bubble. Actually\, the underwater vess
 el is surrounded by an inhomogeneous fluid containing cavities (also descr
 ibed as microbubbles). The distribution of the cavities in the supercavita
 tion volume dictates the pressure field and thus determines the stresses a
 nd forces that act on the vessel and affect its motion and stability. In t
 his research\, we suggest a new approach to studying the bubbles’ format
 ion and learning about the cavities’ distribution in the low-pressure vo
 lume using a stochastic model\, describing the random movement of the cavi
 ties.\n Details: \n 
CATEGORIES:Seminars
LOCATION:Meeting Room 203 - Rocket Propulsion Center

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