The effect of magnetic fi eld magnitude and magnetizable ball sizes on the variation in theirs cooling intensity in magnetic fluid with time

V. V. Gogosov¹ - Kh. D. Iskanderov² - A. Ya. Simonovskii²

¹ Institute of Mechanics of the M.V.Lomonosov Moscow State University, 117192, Moscow, Russia
² Academy of Stavroplol, 355014 Stavroplol, Russia

Abstract
Experiments on cooling the heated magnetizable balls of 19, 14, 2 and 8 mm diameter in diluted magnetic fluid in applied external magnetic fields equal to 39, 68, 122 and 170 kA/m and without field are described. The balls are heated up to the temperature 700 °C and cooled to 100 °C in container filled with magnetic fluid. The container is placed between the electromagnet poles. The thermocouple to perform the measurement of the temperature of the balls is installed In the center of the balls. The effect of the ball dimensions, the magnetic field intensity on the cooling modes with time is studied. It is found the variation in the cooling intensity with time depends on the ball dimensions and applied external magnetic field magnitude. Itis shown that the varying of the magnetic field magnitude affects on the ball cooling modes nonmonotonically. Application of the weak magnetic field equal to 39 kA/m for the ball of 19 mm diameter tends double the cooling intensity in the time interval from 2 to 10 seconds after cooling beginning as compared with the cooling without magnetic field. However, increase of the magnetic field from 68 kA/m up to 170 kA/mm tends to decrease of the cooling intensity. Possible explanation of this phenomenon is given. Comparation of the cooling results of the balls 19, 14, 2 and 8 mm diameter shows that with decreasing the ball sizes the action of the magnetic field on the cooling intensity in the magnetic fluid weakens. Figs 1, Refs 12.