Experimental and Computational Studies on Water Mist Flow in the Horizontal Bore of a Superconducting Magnet: Example of Magnetic Force Application on Micron-Sized Objects

摘要

The effect of a magnetic field on water mist (diamagnetic) is studied both experimentally and numerically. The water mist is produced by ultrasonic atomizers and is fed to a Plexiglas pipe (90 mm inner diameter and 1 m long) which is horizontally placed in a horizontal bore (d = 100 mm) of a superconducting magnet (10 T at the magnet center). The water mist is found to flow out of the other end of the pipe opening when there is no magnetic field (b = 0 T). At b = 8 and 10 T, the mist is stopped at an intermediate location in the pipe and flows out from the inlet opening. In the computation, the water mist is simulated with 1000 particles of 0.01-5 μm in diameter. Brownian motion is considered and the Langevin equation is solved. Various magnitudes of magnetic strength, particle diameters and pressure gradients for air flow are numerically tested. The magnetic effect is obvious for particles with diameters larger than 1 μm. For example, for 3μm particles, only a small amount of particles are able to pass through the weak magnetic field near the cylinder axis to the downstream and sediment over the downward pipe wall.