1990 Fiscal Year Final Research Report Summary
High Speed Two-Phase Boundary Layer Flow of Particle Dispersed Gas and Condensating Vapor
| Project/Area Number |
63460093
|
|---|
| Research Category |
Grant-in-Aid for General Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
Fluid engineering
|
|---|
| Research Institution | Waseda University |
|---|
Principal Investigator |
YOSHIOKA Eisuke Waseda Univ, Mechanical Engineering, Professor, 理工学部, 教授 (50063699)
|
|---|
| Project Period (FY) |
1988 – 1990
|
| Keywords | Fluid mechanics / Boundary layer / Compressible two-phase flow / Particle dispersed gas / Condensation / Computational fluid mechanics / Shock tube experiment / Boundary layer heat transfer |
|---|
| Research Abstract |
High speed flow of particle dispersed gases was studied with special concern to the boundary layer structures adjacent to solid walls. Both of solid and liquid particles were treated in the computational and experimental studies of two-phase shock tube flows. The result provides fundamental understanding about micro-structures in various applications of dispersed two-phase flow mechanics. The result and findings are summarized as follows :
1. Two-phase flow measurement various systems and equipment were developed to measure two-phase flow quantities relating to the high speed transient and micro-scale phenomena in the flow. The wall heat transfer measurement were successfully conducted by utilizing a thin plutinum film gauge which was manufactured by ion-coating technique. A couple of a semi-conductor laser and a photo diode is utilized to qualify the dispersion of particles. Counting of particles during the flight at various location were made by setting up He-Ne laser and a photomulti
… More
plier optical systems. A special interferometry instrumentation was applied to measure thickness of condensation liquid film in a range of the thickness less than several times of the laser wavelength.
2. Boundary layer structure of condensating mixture flow by wall cooling The structure was studied by two computational models of the mixture. In the first model treating respective particles, a spontaneous nucleation theory was introduced in an iterative analysis of the flat plate boundary layer. Profiles of temperature and concentration were obtained before the stage of forming a liquid film on the plate. However, due to a rapid and extreme change phase density, the iterative analysis became difficult. In the second model, the vapor phase is treated as a continuum by introducing a mass concentration equation into the N. S. equation system, and profiles of the two-phase flow separation on a curved wall were obtained. Further improvement is still necessary to obtain the process of forming liquid film in both of the model.
Boundary layer structure modified by solid-particle concentration Lifting motion of particles was found by an iterative analysis of particle motion and the shear layer flow. Due to a transverse motion, collision between particles took place, and initially uniform dispersion changed downstream to take a non-uniform concentration. The particular feature is that the boundary layer is constituted with a clean gas layer adjacent to the wall and a highly concentrated layer of particles at a considerable distance from the wall. Heat transfer feature agreed well with the experiments. Less
|
