Authors have disclosed the flow characteristics of network ducts with which the slot-perforated plate bundles in three rows are arranged in different types. An experimental study was performed to disclose the flow characteristics in network ducts of the slot-perforated plate bundles with which the intersecting angles connecting the centers of gaps of their plates are 30°and 60°, Yespectively. The depth of their ducts was almost the same as the relative length of their plates. The flow patterns were visualized using the tracer method and the velocity variations in the flow field were measured using two-dimensional laser Doppler velocimetry. The secondary flow with vortices and the resulting oscillation of main streams are visualized in the plate bundles. The characteristics of hydraulic resistance and dominant frequency for power spectrum in their ducts are also determined.
A numerical analysis and visualization of the flow and mixing of rich mixture and air inducted into the cylinder through each of the two intake ports of a stratified charge engine have been carried out. Numerical calculations were performed by finite volume method for three types of the intake port configurations: inverse V type, parallel type and V type. Velocity field, flow pattern, turbulent kinetic energy and distribution of mixture concentration in the cylinder during intake and compression strokes were examined. Effects of configurations of the two intake ports on the characteristics of flow and mixing in the cylinder were made clear.
An experimental study was carried out on natural convection in an inclined concentric cylindrical annulus. The effect of angle of inclination on the heat transfer was measured using water as a working fluid. In addition, visualization measurements of both velocity and temperature fields were accomplished with the use of thermo-sensitive liquid crystal. The results indicate that the flow pattern changes considerably from a flow with a buoyant plume for the horizontal annulus to the one recirculating within the enclosure along the wall depending on the angle of inclination and that the mean heat transfer rate is enhanced as the cylindrical annulus is inclined from the horizontal position to the vertical one.
A computer controlled, laser scanning technique has been newly introduced to visuali-zation of arbitrary 3-dimensional surfaces visualization in a space of interest, and applied to 3-D flow visualization in the field of a circular jet flow dynamics. Using the laser scanning visualization system (LSCVS), circumferential phenomena due to vortical structures in a circular jet has been successfully visualized on a series of dif-ferent diameter, coaxial half columnar surfaces. From image analyses, the flow behavior of jet is discussed in terms of such physical quantities as the mean, the root mean square (RMS), and the dissipation for observed concentration images. Some technical viewpoints for the hardware configuration and the image correction method have been also de-scribed in detail, both of which are essentially required due to the characteristic property of the LSCVS. This visualization method would be a very viable tool in observing non-axisymetrical phenomena which are difficult to be visualized with conventional laser light sheet meth-ods.
The experiment of visualizing liquid flow regarding the nucleate boiling heat transfer in saturated water pool in the case of changing the frequency of vapor bubble generation was carried out by solid tracer method under reduced pressure. In the boiling experiment, vapor bubble nuclei were supplied by hydrogen gas, and the experiment was carried out at a constant heat flux. The results obtained by the condition of this experiment are as follows. The state of boiling vapor bubbles changed to isolated bubbles, coupled bubbles with different size, and continuously generated bubbles with the increasing frequency of vapor bubble generation. The heat transfer coefficient became larger with the increasing frequency of vapor bubble generation. The particle tracks and the liquid velocity vectors obtained by visualization experiment were different in three kinds of the state of boiling vapor bubbles mentioned before, respectively, and those possessed the features. The liquid flow within the superheated boundary layer in nucleate boiling heat transfer at low heat flux was considered by relating it to the liquid flow around the vapor bubble.