1995 Fiscal Year Final Research Report Summary
"INVESTIGATION ON EDDY STRUCTURES IN TURBULENT JETS"
| Project/Area Number |
06452173
|
|---|
| Research Category |
Grant-in-Aid for General Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
Fluid engineering
|
|---|
| Research Institution | Institute of Industrial Science, University of Tokyo |
|---|
Principal Investigator |
KABAYASHI Toshio University of Tokyo, Institute of Industrial Science, Professor, 生産技術研究所, 教授 (50013206)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
OSHIMA Mari University of Tokyo, Institute of Industrial Science, Research Assist., 生産技術研究所, 助手 (40242127)
SAGA Tetsuo University of Tokyo, Institute of Industrial Science, Research, Assist., 生産技術研究所, 助手 (30013220)
TANIGUCHI Nobuyuki University of Tokyo, Institute of Industrial Science, Assoc.Prof., 生産技術研究所, 助教授 (10217135)
|
|---|
| Project Period (FY) |
1994 – 1995
|
| Keywords | Turbulence / Jet Flow / Eddy Structure / Visualization Measurement / Large Eddy Simulation / Thermo Sensitive Liquid Crystal / Micro Capsel / Subgrid Scale Model |
|---|
| Research Abstract |
A purpose of this research has been to investigate effects of eddy structures onto a mechanism of kinetic energy dissipation and heat transfer in turbulent jets, where eddy structures are generated and deformed in the initial region then a statistically similar profile is developed in the following turbulence region. Two approaches were adopted : one was a experimental measurement using visualization techniques, and the other was a large eddy simulation (LES) of turbulnce.
In the experimental approach :
1) A new technique, PITV (Particle Imaging Thermometry and Velocimetry), was developed. which was a simultaneous measurement of velocity and temperature using liquid clystal capseled in small particles. An optical characteristics of liquid clystal responding temperature was examined because it could e changed when the crystal was capseled in a small particle. Then using the particles containing the liquid cystal as tracers, velocity and temperature field were visualized and analyzed simul
… More
taneously.
2) An experiment of an axisynmetric jet with/without bouyancy was performed. It was proved that by the above method a resonable data could be obtaine in the statistical values of velocity, temperature and their turbulent corelations.
In the numerical research :
3) For avoiding the singularity problem in the numerical method on the cylindrical coordinates, a practical method was developed using two coodinate systems alternatively. This method was validated in the LES of a turbulent swirling flow in a circular pipe. The LES in such a practical problem had been less investigated before, mainly due to the above coordinate problem.
4) A dynamic model by Germano and a scale similarity model by Bardina were investigated in the LES for applying them to the jet flows which include a laminar-turbulence transition. Most problem for the engineering application of these models had been in the instability of their calculation procedures. Therefore, the stable and effective formulation of these models was investigated in the practical LES using a finite diference method (FDM) and the finite element method (FEM)
An analysis of the LES result of a plane turbulent jet indicated vortex streaks flowing to the streamwise and winding around the spanwise main vortexes. The streak vortexes was observed only in the intial region, then disappeared in the similar profile region where a fully three-dimensional eddies were suddenly developed. These structures had not been reported explicitly by the experimental researches. Less
|
