Hiroo Okanaga

Experiments for Verifying Performance of 3-Dimensional Particle Image Velocimetry on Genetic Algorithms

This particle image velocimetry has been studied to find velocity vectors of illuminated particle motion by combinations for identifying particles between two sequential digital flow images. The authors propose the method of applying genetic algorithm to the particle image velocimetry. It is enable us to get the plural of velocity vector at the same time. This paper explains the application of this method to 3-dimensional particle image velocimetry. This method is based on a space correspondence for calculating 3-dimensional particle positions and a time correspondence for calculating the particle velocity vectors. In addition, this paper ijntroduces the results of a numerical simulation using flow model around a prism.

Flow Around a Circular Cylinder with and without Grooves

It is well-known the dimples on the surface of golf ball increase its flying distance. But the detailed mechanism of flow by dimples has not been made clear. The purpose of this research is to make clear the mechanism of this flow in the case of changing the number and shape of dimples by computation and experiment. As the first stage of this research, this paper deals with the effect of the grooves as modeled dimples that were put on the surface of a circular cylinder. The computation was performed by solving the Navier-Stokes equation using the QUICK method. The grooves were formed in the same shape as a golf ball and the number of dimples is 32. The results by computation of the flow pattern around the circular cylinder with and without grooves showed large difference.

Flow around a Circular Cylinder with Grooves

It is well-known the dimples on the surface of golf ball increase its flying distance. But the detailed mechanism of flow by dimples has not been made clear. This paper deals with the effect of the grooves as modeled dimples that were put on the surface of a circular cylinder. The computation was performed by solving the Navier-Stokes equation using the QUICK method. The grooves were formed in the same shape as a golf ball and the number of dimples is 32. The experiment was performed flow visualization using spark tracing method. These results of the flow pattern around the circular cylinder showed good agreement.

STUDY ON THE CYLINDRICAL COMBUSTER FLOW WITH SWIRLING FLOW

This paper is described an experimental study on circular duct flow with wirling flow. The swirling flow is very important for gas turbine combustor, fornaces, etc.In this study, the velocity and flow pattern of the swirl flow in a circular duct is measured using a laser Doppler Velocimeter (LDV) when the expansion ratio(D/d) in circula duct is varied from 1.5 to 3.0.Further, the flow visualization is carried out using a streamer, sparktracting method and alminium powder method.From these results, the present study clarifies the flow patterns and the size and shape of recirulation, eye of vortex and sub-recirculation zones for the expansion ratio.

Flow Visualization of Potential Flows around a Ball and Wings by a Personal Computer

Potential flows can be expressed using complex function. Therefore, these flows can be easily visualized on a personal computer. In the present paper, flow visualization of two potential flows have been carried out by a NEC personal computer system. One is a flow around a rotating ball, and the other is a flow around wings. Results of theoretical of analysis are presented by streamline. Computer program is written by FORTRAN on MS-DOS.