Effect of immersion depth

In addition to non-Newtonian flow, the main correction necessary for concentric cylinder measurements is that on account of end effects. Because the inner cylinder is not infinitely long, there is drag on the ends as well as on the face of the cylinder. The correction appears as an addition, to the length, b. The correction is best deterrnined by measuring the angular velocity and torque at several values of b, that is, at various depths of immersion. The data are plotted as M/Q vs b, and extrapolation is made to a value of at M/H = 0. The quantity (/i + h ) is substituted for b in the various equations. 

With a US homogenizer, the flow pattern of the liquid depends on the distance from the horn tip. Since flow pattern (mixing) is the physical effect of US irradiation, any change in the flow pattern due to horn immersion may affect the crystallization rate. There is an optimal, specific horn immersion depth for each US device and irradiated medium which must be established experimentally on a case by case basis. 

The inability to control precisely the reference junction temperature or to obtain accurate compensation would also affect thermocouple reliability. In the case of an ice bath, factors that can cause the junction temperature to depart from 0°C include non uniformity in the temperature of the ice-water mixture, small depth of immersion, insufficient ice, and large wire sizes (conduction effects). Reference 46 describes various sources of errors in an ice bath. 

The measured capillary pressure P can be expressed via the excess maximum pressure in the measuring system P, the hydrostatic liquid pressure P = ApgH, and an excess pressure Pj. The excess pressure results between the measuring system and the bubble due to dynamic effects, such as aerodynamic resistance of the capillary, viscous and inertial effects in the liquid etc. (Ap is the difference between the densities of liquid and gas, g the gravity and H the immersion depth of the capillary into the liquid.) Therefore, we have... 

Computations of power, temperature and velocity distributions were made for two cases where the electrode immersion depths and currents were varied. In the first case, the three electrodes were immersed in the slag to a uniform depth of260 mm, and the currents were 24.5, 24.7 and 21.7 kA for the electrodes El, E2 and E3, respectively. In the second case, the immersion depth was increased to 540 mm, and the currents were increased to 27.3,29.1 and 25.4 kA for El, E2 and E3, respectively. In order to represent the 3-D effects, the results are shown in two mutually peipendicular planes (1) the longitudinal symmetric plane of the furnace (Plane-I), and (2) a cross-sectional plane (Plane-II) which extends from the symmetric plane to the side wall, intersecting the middle electrode E2 at the centre. 

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