超低扬程双向流道泵装置压力脉动特性研究

沿江泵站承担了灌溉、排涝、水环境治理等双向引排水任务,受长江潮位影响,双向水泵装置经常运行至零扬程附近,实际流量超过设计值30%以上,流道水力损失增大,流态紊乱,易引起水力振动,影响机组运行安全。采用CFD技术对沿江某低扬程双向流道泵装置进行水流流动及压力脉动特性研究,并结合模型试验进行验证。研究表明:超低扬程工况下,泵装置进出水流道盲端存在较大回流,出水流道内回流强度较大,导致水力损失增加;进水流道内测点主频为6倍转频,次主频为1/8倍转频;出水流道内测点主频无明显规律,但幅值相近,低频脉动占主导地位。研究成果可为沿江泵站超低扬程工况下水泵装置水力振动研究提供参考。

Pressure fluctuation characteristics of bidirectional pumping system under super-low head operation

The pumping stations along the Yangtze River have been used for the bidirectional tasks of water diversion and drainage such as irrigation, storm drainage, and water environment control. Influenced by the tidal level in the river, these bidirectional pumping stations often operate near zero head, while the actual flow rates exceed the design value by up to 30%. This leads to an increase in the hydraulic loss of flow passages, a disorder in flow patterns, and a potential of hydraulic vibrations, thereby affecting the operation safety of the pump systems. This study examines the flow behaviors and pressure fluctuations for a low-head pumping station through CFD simulations, and verifies the calculations using scale model tests. The results show that under the super-low head condition, large-scale backflows occur in the blind end of its inlet and outlet passages, and the one at the outlet has a great intensity and causes a significant increase in hydraulic loss. At all the measuring points in the inlet passage, the dominant and secondary frequencies of fluctuations are 6 and 1/8 times the pump rotating frequency respectively. in the outlet, the dominant frequencies are irregular, but the amplitudes at different locations are similar and low-frequency fluctuations are dominant.