| Project/Area Number |
03650163
|
|---|
| Research Category |
Grant-in-Aid for General Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
Fluid engineering
|
|---|
| Research Institution | NIHON UNIVERSITY |
|---|
Principal Investigator |
KOMODA Hiroyuki NIHON UNIV., COLL.OF SCI & TECH., PROFESSOR, 理工学部, 教授 (00058710)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
MATUMOTO Akira NIHON UNIV., COLL.OF SCI.& TECH., LECTURER, 理工学部, 専任講師 (80130607)
HANDA Naoko NIHON UNIV., COLL.OF SCI.& TECH., PART-TIME LECTURER, 理工学部, 講師 (10058828)
|
|---|
| Project Period (FY) |
1991 – 1993
|
| Project Status |
Completed (Fiscal Year 1993)
|
| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1993: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1992: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1991: ¥1,100,000 (Direct Cost: ¥1,100,000)
|
|---|
| Keywords | LAMINAR BOUNDARY-LAYER TRANSITION / SPOT GENERATOR / LAMINAR SPOT / MULTI-HOT-WIRE PROBE / TURBULENT SPOT / MULTI-POINT ANEMOMETRY / CONTOUR OF INATANTANEOUS STREAMWISE VELOSITY DEVIATION / 平板境界層 / 遷移 / 乱流 / 多点同時測定 / 境界層 |
|---|
| Research Abstract |
The disturbance induced artificilly by ejecting a short duration jet (1-2 ms) from a small hole drilled on the wall into a supercritical two-dimensional laminar boundary layr, develops quite regularly to a certain downstream position, beyond where irregularities come in and finally evolves into a turbulent spot. we had found that in the downstream extent where its development is regular, the velocity oscillograms when the disturbance swims by, are well reproducible whenever the jet ejects ; neverthless the plane shape and its growth are similar to a turbulent spot, and so it was named "laminar spot". The excellent reproduciblity allows us to map out the instantaneous flow field of the laminar spot by using of many velocity oscillograms each of which were masured in a different time and at a different position. The details of the flow filed of the laminar spot were studied through drawing the contour map of the streamwise instantaneous deviation velocity from the undisturbed laminar boundary layr velocity with the aid of a multi-hot-wire anemometer.
The main results are as follows : 1) The whole process of the structure and its downstream development of the laminar spot were revealed in the form of the contour map of the intantaneous streamwise velocity deviation. 2) It was clarified that the protuberance on the forward part of the spot develops into a ring vortex facing upstream, and the velocity distribution across the vortex and its convection speed were determained. 3) The dowmstream growth of the spanwise width of the laminar spot is as rapid as a turbulent spot. Its mechanisum was visualized and became clear by chasing downstream the time series of the contour map.
|
