隔舌间隙对双吸离心泵内部非定常流场的影响

Effect of Volute Tongue-impeller Gaps on the Unsteady Flow in Double-suction Centrifugal Pump

为了研究隔舌间隙对双吸离心泵内部非定常流场的影响,采用大涡模拟方法和滑移网格技术,对双吸离心泵在设计工况下的内部湍流进行了数值计算,重点分析了5组隔舌间隙下泵内非定常流场特性及压力脉动特性。结果表明:随隔舌间隙增大,水泵扬程整体呈上升趋势,效率则整体呈下降趋势;蜗壳内压力脉动频率以叶片通过频率为主,主频和压力脉动幅值均随隔舌间隙的增大呈减小趋势,隔舌间隙增加4%时,隔舌位置1倍叶片通过频率处的脉动幅值降低9%左右;叶片区压力脉动频率以叶轮转频为主,最大压力脉动幅值均出现在2倍叶轮转频处,当隔舌间隙比设计隔舌间隙减小4%时,叶片正面中心位置2倍叶轮转频处压力脉动幅值增加约38%。

In order to study the influence of tongue-impeller gap on the unsteady flow in a double-suction centrifugal pump,a research was presented on the internal unsteady flow,especially on the pressure pulsations.The large eddy simulation method with sliding mesh technology was used to investigate this kind of unsteady flow characteristics in a double-suction centrifugal pump at design condition.Five different impellers with different outlet diameters,corresponding to different tongue-impeller gaps were considered.The results indicated that the head rise showed an increasing tendency with lager tongue-impeller gap,while the efficiency had an overall downtrend.The results also showed that the blade passing frequency dominated the pressure fluctuations in the volute,while rotating frequency dominated in the impeller.Meanwhile,the tongue-impeller gap increasing resulted in a significant reduction of the maximum pressure fluctuation amplitude both in the volute and impeller.When the gap increased by 4%,the maximum amplitude at one time of blade passing frequency near the volute tongue was reduced by about 9%,while the maximum amplitude at two times of rotating frequency in the center of blade pressure side increased by about 38%.