| Budget Amount *help |
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2005: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2004: ¥200,000 (Direct Cost: ¥200,000)
Fiscal Year 2003: ¥2,800,000 (Direct Cost: ¥2,800,000)
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| Research Abstract |
Turbulent characteristics in packed beds are investigated both experimentally and numerically. In the experiment, a packed bed is simplified as an arrangement of cylinders. Measurement of pressure drop and turbulent kinetic energy, and flow visualization in the arrangement of cylinders are conducted. In the numerical simulation, a mathematical model describing turbulent flows in packed beds is developed, based on k-ε model and k-l_m turbulence model. The simulation is conducted in two cases. In case1, the cylinders are staggeredly arranged to simplify packed beds. In case2, the arrangement of cylinders is modeled using void fraction. The results obtained in this study are summarized as follows.
1.Pressure drop increases with increasing Reynolds number or decreasing void fraction.
2.Turbulent kinetic energy rises rapidly after inflow to the arrangement of cylinders, and then approaches to a constant value in the downstream. Turbulent kinetic energy increases as Reynolds number increases.
3.The flow visualization shows the development of turbulences caused by the cylinders. However, the turbulent eddy scale is limited by the gap between cylinders in the downstream.
4.In the simulation when the cylinders are arranged, calculated results of the turbulent kinetic energy show the similar tendency with experimental ones.
5.When the arrangement of cylinders is modeled by void fraction, the production of turbulent kinetic energy caused by the cylinders is considered in the conservation equation of turbulent kinetic energy. When k-l_m model is used, the calculated results are greatly affected by the mixing length. When k-ε model is used, on the other hand, the calculated results are greatly affected by the inlet condition. Therefore, the further research will be required for the determination of the mixing length in k-l_m model and the inlet condition in k-ε model.
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