Hiroshi Ishigaki

Fundamental Characteristics of Mixed Convective Laminar Flow in Rotating Curved Pipes. Scaling Law and Thermo-Fluid Structure.

The fluid flowing in rotating heated curved pipes is subjected to three body forces : centrifugal, Coriolis and buoyant forces. Fully developed laminar flow in rotating coiled pipes is investigated through similarity arguments and computational studies. The thermal boundary conditions at the wall are uniform wall heat flux axially and uniform wall temperature peripherally. Flow and heat transfer characteristics are elucidated for the case when they are governed by four parameters : Dean number, Prandtl number, body force ratio and buoyancy parameter. Detailed structures of velocity and temperature fields are shown for wide range of these parameters.

Development Characteristics of Mixed Convective Laminar Flow and Heat Transfer in Heated Pipes. Parallel Rotating Pipes and Horizontal Pipes.

Flow and heat transfer in heated pipes rotating about all axis parallel to the pipe axis are reduced to the same problem as those in heated stationary pipes situated horizontally, when the radius of rotation of the pipe is large compared with the pipe radius. The purpose of this study is to clarify the development characteristics, common to those two flows, of mixed convective laminar flow and heat transfer through similarity arguments and computational studies. A new dimensionless axial distance is introduced to correlate the characteristics.

Flow Characteristics and Centrifugal Instability in a Curved Square Duct.

A numerical study is made to investigate fully developed laminar flow characteristics in a curved square duct of finite curvature ratio. It is shown that, above critical Dean numbers, a pair of Dean vortices due to centrifugal instability appears near the center of the outside wall in addition to the secondary flow vortices. A stability diagram is given in the domain of Dean number and curvature ratio. On the basis of a similarity consideration, we propose new nondimensional expressions of flow characteristics that represent a whole range of parameters inclusively. Two friction factors are proved to be different for small curvature ratio, and a correlation is developed.

Laminar Flow in a Pipe Rotating around a Perpendicular Axis.

A finite-difference procedure is applied to analyse the fully developed laminar flow characteristics in a pipe rotating about a perpendicular axis. We propose a new combination of two parameters of KL and number Ro as characteristic non-dimensional numbers. The four flow regimes are classified for large and srmall KL, Ro. We present a numerical formula for friction factor which is valid for wide range of KL and Ro. The formula agrees well with experimental data.