1991 Fiscal Year Final Research Report Summary
Microscopic Material Damage due to High-Speed Impact of Droplets/Pulsed Jet against a Solid Wall and Related Cavitation Phenomena
| Project/Area Number |
01420022
|
|---|
| Research Category |
Grant-in-Aid for General Scientific Research (A)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
Fluid engineering
|
|---|
| Research Institution | Tohoku University |
|---|
Principal Investigator |
SHIMA Akira Tohoku University, Institute of Fluid Science, Professor, 流体科学研究所, 教授 (30006168)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
TOMITA Yukio Hokkaido University of Education, Hakodate College, Associate Professor, 教育学部函館分校, 助教授 (00006199)
TAKAYAMA Kazuyoshi Tohoku University, Institute of Fluid Science, Professor, 流体科学研究所, 教授 (40006193)
KOBAYASHI Ryoji Tohoku University, Engineering, Professor, 工学部, 教授 (70006170)
MAEKAWA Ichiro Tohoku University, Engineering, Professor, 工学部, 教授 (70018464)
|
|---|
| Project Period (FY) |
1989 – 1991
|
| Keywords | Droplet / Pulsed Jet / High-Speed Liquid Impact / Cavitation Bubble / Shock Wave / Micro-Fracture / Damage Pit / Gas Gun |
|---|
| Research Abstract |
In the former half of the research project we conducted an experiment on the high-speed impact of a pulsed water jet, which was produced by using a powder gas gun, against a solid wall with the intention of investigating the high-speed impact of liquid flow consisting of a number of small droplets. In this case a sabot was used to carry small amount of water, and the water flowed up after the sabot stopped at the sabt stopper due to the inertia effect. Subsequent impact of this pulsed water jet against a target resulted in forming numerous microscopic craters on the material surface. We also discussed about the wave phenomena to be generated inside a droplet and subsequently induced cavitation.
On the other hand, in the latter half of the project, we carried out an experiment on the highspeed impact of a pulsed water jet with a sharped precursor, so-called Munroe jet. It was produced by impacting a plastic projectile with a neoprene rubber which was separating small amount of water. We clearly observed the development of a crack caused by the high-speed impact of a Munroe jet when using an acrylic plate as a target. Furthermore when a target material was aluminum we obtained the damaged surface exactly corresponding to the structure of a pulsed jet. We have some results as following ; (1) The damaged area does not depend on the impact velocity of a pulsed water jet but on the stand-off distance from the nozzle exit, (2) The central damage pit increases in size with increasing the liquid jet impact velocity, (3) The size of crater is apt to increase as increasing the kinetic energy of a pulsed jet, and so on.
|
