出鋼造塊時の熔鋼の流体力学的研究(I)

抄録

The inclusions or blow holes of fully-killed steel ingots are affected by the conditions of the molten steel-stream which is poured from a nozzle in ingot-making.
The preliminary experiments were carried out through the nozzles of various shapes (dia; 1mmφ-10mmφ) and at various heads (0-1800mm) by using mercury, water and some water solutions. If the stream-condition was assumed to be mainly influenced by the Reynolds number, the results of this experiment through 10mmφ nozzle by mercury corresponded to those through 20mmφ nozzle by molten iron. The research was done without a stopper: it is near the case when the stopper is fully opened.
The results obtained were as follows.
(i) The stream which was poured from a nozzle was a perfectly stable laminar flow, only when the head of the liquid (the distance from the surface of the liquid to the entrance of the nozzle) had some limitted value. When the head was too large the stream was turbulent, and when it was too small, the stream was dripping. They were photographed at the ex posure of 1/1000 second.
(ii) The range of the head where the stable laminar flow was obtained through one nozzle was changed by physical properties of the liquid. Especially by increase of the viscosity, the transition point from turbulence to laminar flow was moved to a high head. The range of laminar flow was extended.
(iii) For the purpose of extending the range of the head where laminar flow was achieved, the short nozzle was better than long one within the limit of this experiment. The nozzledia was 10mmφ, and the length was 30mm-100mm.
(iv) On the result of (iii), the nozzles with tapper at the entrance and short parallel straight part at outlet were designed. They were recognized to have a good character of flowing.