旋流消能工内空腔旋流的流速特性

Study on Velocity Characteristics of Cavity Gyrating Flow in Gyrating Discharge Tunnel

为了揭示空腔旋流的内部流场特性,以公伯峡水平旋流消能工为例,结合数值模拟和试验成果,研究空腔旋流的流速特性。结果表明,随半径的增大,同一轴向断面的切向流速呈先增大后减小的规律,具有组合涡的分布特性,而轴向流速具有先急剧增大,而后平缓变化的特性。旋流消能工内空腔旋流的流动以切向流动和轴向流动为主,且沿程是由切向流速向轴向流速转变的,并与旋流角的沿程分布相印证。组合涡指数是旋流内部流动自由程度和能量损失的体现,在研究流段上其值介于-0.8~0.5之间,并随半径的减小而减小;组合涡指数的沿程分布表明旋流消能工内的空腔旋流沿程是由准强制涡向准自由涡转变的。推导并建立压强及流量的计算公式,代入数值模拟结果验证了空腔旋流的组合涡运动规律,成果可为空腔旋流内部微观流动特性的研究提供参考。

In order to reveal the inner flow characteristics of cavity gyrating flow,the velocity characteristics of Gongboxia horizontal gyrating discharge tunnel were studied based on the numerical simulation and experimental results. The results indicated that with the increase of the radial,the tangential velocity increased at first,and then decreased,and had a distribution characteristics of combined vortex,while the axial velocity increased rapidly at first,and then changed slowly. The cavity gyrating flow in gyrating discharge tunnel was mainly tangential flow and axial flow,and changed from the tangential flow into the axial flow along the gyrating discharge tunnel,which was proved by the rotation angle. The freedom degree and energy loss of cavity gyrating flow were reflected by the combined vortex index,which decreased with the decrease of the radial in the range from- 0. 8 to 0. 5. The variations of the combined vortex index indicated that the cavity gyrating flow changed from quasi forced vortex to quasi free vortex along the gyrating discharge tunnel. The computational formulas for pressure and discharge were established based on the motion rule of combined vortex,and the combined vortex motion law of the cavity gyrating flow was verified by the numerical datum. The results can provide a reference for the internal micro flow study of the cavity gyrating flow.