Experimental study of the ACRT Ekman flow

The stability of the Ekman flow during ACRT (accelerated crucible rotation technique) process, and the effects of the crucible diameter Φ, the maximum variation of the rotation speed, Δ_max , as well as the liquid height H in the crucible on the Ekman flow, were studied with hydraulic analogue experiments. The result shows that, if Reynolds number Re ≤ Re^C1 (the low critical Re), the Ekman flow is stable, if Re ≥ Re^C2(the high critical Re), the Ekman flow during the crucible deceleration period is unstable, and the Ekman flow height h increases with increase of the crucible diameter Φ and the maximum variation of the rotation "speed Δω_max. When Re ≤ Re^C1, the relation between the ratio h / R (R = 0.5Φ) and Re² is linear. When the liquid height H < H^* (a critical value), the Ekman flow height h decreases with decrease in the liquid height H.