Research and Development of Fiber L2F
| Project/Area Number |
02555041
|
|---|
| Research Category |
Grant-in-Aid for Developmental Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
Fluid engineering
|
|---|
| Research Institution | Kyushu University |
|---|
Principal Investigator |
HAYAMI Hiroshi Kyushu University, Institute of Advanced Material Study, Professor., 機械物質科学研究所, 教授 (10038606)
|
|---|
| Project Period (FY) |
1990 – 1991
|
| Project Status |
Completed (Fiscal Year 1991)
|
| Budget Amount *help |
¥4,600,000 (Direct Cost: ¥4,600,000)
Fiscal Year 1991: ¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1990: ¥2,800,000 (Direct Cost: ¥2,800,000)
|
|---|
| Keywords | Flow Measurement / Laser / Laser Velocimeter / L2F / Diode Laser / Optical Fiber |
|---|
| Research Abstract |
A new type laser-2-focus velocimeter (L2F) was developed to materialize a small size, a low price and an easier operation. An optical system and a signal processing system based on an optical fiber or based on a diode laser were designed and were built up. The design specifications of new systems were tested applying to a flow measurement in a wind tunnel or in a rotating impeller.
At the first step, a fiber L2F with an optical fiber of 8 m in length used between the laser source and the optical head was developed. The size of the fiber L2F was reduced to a half in weight and a third in volume compared with the original L2F. The optical S/N ratio of the fiber L2F was not deteriorated for application to a flow measurement in a rotating impeller, when the optical shutter was installed ahead of the optical fiber according to the behavior of polarized light in an optical fiber.
At the second step, a diode L2F with a transmitter optics of 48 mm in diameter and of 120 mm of measuring distance
… More
was developed, the size of which is 324 mm in length, 98 mm in width and 140 mm in height, and the weight is 5kg. A diode laser of 840 mm in wave length was used as a light source, and the scattered light from a particles was detected using an avalanche photodiode. An electric amplifier was designed with high sensitivity against the diode laser. The measuring volume of the diode L2F was measured using a fine wier of 5 mum in diameter with a mechanical traversing system.
It was possible to make a flow measurement at I mm close to the bottom wall even when the laser beam was inserted into a small-sized wind tunnel normal to the wall, and this confirmed a high S/N ratio of the diode L2F system. In the case of low turbulence flow, the maximum sampling rate was 2kHz and the probability of a particle traveling through the two foci was beyond 80 percent so that a measuring time was reduced significantly by narrowing the distance between the two foci to 0.1 mm. Velocity distribution in a two-dimensional wake behind a circular cylinder was measured. The diode L2F was applicable to a flow measurement even in a high turbulence flow with 20 % in transverse turbulence intensity. Less
|
Report
(3 results)
Research Products
(4 results)
