Drag friction control in laminar airflow in circular pipe using permanent magnets

Summay form only given. Introduction Reducing fluid frictional drag is an important hydrodynamic issue for practical applications; there have been many studies on drag reduction. In our previous study, we found that permanent magnets could be used to reduce the drag friction of laminar airflow in a circular pipe [1]. The drag reduction rate decreased as a function of the Reynolds number in the laminar flow regime, and it reduced to a low percentage when the Reynolds number was greater than 3000 in the turbulence airflow regime. These results suggest that the velocity of the boundary airflow on the pipe wall surface was accelerated by the magnetic field gradient produced by the permanent magnets attached to the outer pipe surface. In this study, we focused on the magnetic field direction in a pipe wall and compared the drag friction in the cases of magnetic fields that are perpendicular and parallel to the airflow. 2. Experimental Experiments were performed to measure the air pressure drop in circular steel pipes. Ring-type permanent magnets with their magnetic field parallel to the airflow and cuboid-type magnets with their magnetic field vertical to the airflow were prepared. Figure 1 shows the magnet positions on the circular pipe wall in this experiment. In this experimental system, the airflow was controlled by the inlet valve, and the flow rate was measured by a mass flow meter at the outlet. The pressure difference at the test section was measured by means of a pressure transducer in the cases of different types of magnets. The reduction ratio as a function of distance between each magnet is shown in Fig. 2. It was found that the ringSummay form only given. Introduction Reducing fluid frictional drag is an important hydrodynamic issue for practical applications; there have been many studies on drag reduction. In our previous study, we found that permanent magnets could be used to reduce the drag friction of laminar airflow in a circular pipe [1]. The drag reduction rate decreased as a function of the Reynolds number in the laminar flow regime, and it reduced to a low percentage when the Reynolds number was greater than 3000 in the turbulence airflow regime. These results suggest that the velocity of the boundary airflow on the pipe wall surface was accelerated by the magnetic field gradient produced by the permanent magnets attached to the outer pipe surface. In this study, we focused on the magnetic field direction in a pipe wall and compared the drag friction in the cases of magnetic fields that are perpendicular and parallel to the airflow. 2. Experimental Experiments were performed to measure the air pressure drop in circular steel pipes. Ring-type permanent magnets with their magnetic field parallel to the airflow and cuboid-type magnets with their magnetic field vertical to the airflow were prepared. Figure 1 shows the magnet positions on the circular pipe wall in this experiment. In this experimental system, the airflow was controlled by the inlet valve, and the flow rate was measured by a mass flow meter at the outlet. The pressure difference at the test section was measured by means of a pressure transducer in the cases of different types of magnets. The reduction ratio as a function of distance between each magnet is shown in Fig. 2. It was found that the ring magnets increased the drag friction, while the cuboid magnets decreased the drag friction. In addition, the drag friction increased as the distance between each ring magnet became less. magnets increased the drag friction, while the cuboid magnets decreased the drag friction. In addition, the drag friction increased as the distance between each ring magnet became less.