双向流道轴流泵装置的飞逸特性

为研究双向流道轴流泵装置的飞逸特性,以引江济淮枞阳站泵装置模型为研究对象,基于RANS方程和RNG k-ε模型,应用CFX软件对双向轴流泵装置全流道进行了非定常数值模拟,获得了不同扬程下的流量值及飞逸转速值,计算得到了单位飞逸转速.通过数值计算结果与试验结果相比较,验证了数值计算方法的正确性.结果表明:单位飞逸转速随着叶片安放角的增大而逐渐减小;水流通过泵段后流动变得不稳定,在出水流道中产生大量旋涡;叶轮进口处压力脉动主频为叶轮转频的叶片倍数,压力脉动幅值从轮毂到轮缘逐渐增大;叶片吸力面中部压力分布较不规律,叶片压力面头部及吸力面尾部存在高压区,且面积随飞逸扬程增加而变大;叶片尾部流速较大,边缘存在流动分离现象,而头部存在低速区域,扬程增大后低速区面积增大,流场更加不稳定.研究结果可为泵装置的设计优化及安全管理提供一定参考.

Runaway characteristics of two-way passage axial-flow pump installation

In order to gain runaway characteristics of two-way passage axial-flow pump installation, the axial-flow pump model with two-way flow passage installation in Zongyang Pump Station was used as an investigated object. The unsteady flow field in the installation was simulated numerically by using CFX software, based on the RANS equations and RNG k-ε turbulence model. The runaway speeds and flow rates were obtained under different heads. Finally, the unit runaway speed was worked out.The correctness of the numerical simulation was validated by comparison with the experimental results. The internal flow field in the pump installation shows an unstable pattern behind the pump and significant numbers of vertex occur in the outlet passage. The pressure distribution is irregular in the middle of the blade suction side, and a high pressure zone exists on the blade pressure side near the leading edge and on the blade suction side near the trailing edge, respectively. Moreover, the zone area increases with increasing runaway head. Flow separation exists at the blade trailing edge, and a low velocity region exists on the blade leading edge. The results can provide a good reference for design and safe operational management of the axial-pump installation.