旋转射流流线分析及旋流强度的计算

ANALYSIS OF FLOWLINE AND CALCULATION OF WHIRLING FLOW INTENSITY OF ROTATIONAL JET

为了研究旋转射流的流动特性以及喷嘴和叶轮的几何形状对旋转流体旋流强度的影响，对旋转射流的流动及旋流强度进行了理论分析及计算。结果表明，在理想情况下，旋转射流的流线为一条对数螺旋线。为了使水力损失最小，导向叶轮的外形应与其流线相一致，旋流强度的大小取决于喷嘴的各个参数及叶轮的几何形状。同时利用五孔探针对不同旋流强度的喷嘴进行了轴向速度、切向速度的实测试验。试验结果表明，在旋转射流的主体段，轴向速度剖面呈现出“Ｍ”形分布特点，切向速度剖面呈现“Ｎ”形分布特点。旋流强度越大，旋转射流轴向速度越小，切向速度越大。旋转射流的能量随旋流强度的增加，衰减加快，射程变短。

The influences of nozzle and turbo geometry on whirling flow intensity of rotational jet and rotational jet flow performance are studied. A theoretical analysis and calculation about whirling flow and intensity of jet corresponding to rotation nozzle are carried out. The results show that flowline of ratational jet is a logarithmic spiral curve under ideal conditions, and the outside geometry of the minimum lead turbo should be consistent with the flowline in order to get the less hydrauolic loss. The whirling jet intensity depends on the parameters of nozzle and turbo geometry. According to variable rotatinal flow intensity of nozzle,the axial and tangential velocity are measured by using five hole probe. The measured results indicate that axial velocity profile shows the distribution performance as M type, and tangential velocity profile shows the distribution performance as N type. The higher the whirling flow intensity is, the lower axial velocity is, and the higher tangential velocity is. When the whirling flow intensity increases, the rotational jet power decreases fast and the action distance will shorten.