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穿流式搅拌桨桨叶上的开孔所引起的射流对于提高搅拌效率、降低搅拌能耗起着重要的作用。采用模拟实验方法,研究了全混状态下喷孔出口流速、孔径和孔长对水射流半扩展角β和源点xp/D的影响。研究结果表明:喷孔孔径、孔长以及喷孔前流体的湍动程度对射流发展有很大影响,存在一临界喷孔长径比(H/D)0,1.31 (H/D)0 1.67。当H/D≤(H/D)0时,β随速度(或Re)增加而增大,xp/D随Re增加变化很小;当(H/D)>(H/D)0时,β随速度(或Re)增加而减小,xp/D随Re增加而减小。为了获得较好的混合效果,搅拌桨桨叶上的开孔所引起的射流应有尽量大的扩展效果,因此桨叶上开孔的长径比应小于(H/D)0。
The jet caused by the opening on the flow paddle blade plays an important role in improving the stirring efficiency and reducing the energy consumption of stirring. The effects of flow velocity, pore size and orifice length at exit of full nozzle on the half-expansion angle β and the source point xp / D of water jet were investigated by means of the simulation experiment. The results show that there is a critical orifice ratio (H / D) 0,1.31 (H / D) 0 1.67 for jet development due to the influence of orifice diameter, orifice length and the turbulence of the fluid before the orifice. . When H / D ≤ (H / D) 0, β increases with velocity (or Re), xp / D changes little with Re; β decreases with increasing velocity (or Re), and xp / D decreases with increasing Re. In order to obtain a better mixing effect, the jets caused by the openings in the paddle blades should have as large an expansion as possible, so the aspect ratio of the holes in the paddle should be less than (H / D) 0.