为了研究空化流动下灯泡贯流式水轮机中叶顶间隙数值变化对其压力脉动特性 的敏感性，揭示不同叶顶间隙值对灯泡贯流式水轮机非定常流动特性的影响． 以某电站原 型机为研究对象进行全流道数值计算和模型试验研究，用 4 种间隙 δ 变化方案对压力脉 动特性进行比较． 分析了叶顶间隙处的流场结构，并对数值计算结果和模型实验结果进行 了对比． 结果表明:文中所使用的方法可以基本反映出水轮机内部的流动情况; 当空化系 数开始降低时，水轮机的效率发生变化，水力性能降低，达到临界空化系数时，效率下降明 显;受到空化加剧的影响，叶片背面处监测点的压力脉动幅值增加，靠近轮缘处幅值大于 叶片中部和轮毂处，当局部压力降到空化压力以下时波动不再剧烈，“削波”现象产生; 随 着叶顶间隙值的增加，转轮间隙处空化程度加剧，空化形态由间隙空化演变为翼型空化， 并出现泄漏涡空化;叶片反面轮缘处压力脉动主频与叶片转频相差不大，较大的叶顶间隙 值可以有效降低轮缘处高频压力脉动，然而泄漏流动加剧会导致空化更为严重． 因此，选 取的叶顶间隙数值对于灯泡贯流式水轮机在稳定运行和降低振动噪声方面具有重要的 意义． 

In order to study the characteristics of the pressure fluctuation of bulb tubular turbine effected by tip clearance under the cavitation flow and to reveal the various tip clearance of bulb tubular turbine influence on the unsteady flow，numerical calculation and model test research prototype on whole flow passage are used to compare with pressure fluctuation characteristics on the four clearance schemes on the basis of the SST k-ω turbulence model and moving mesh． Then the tip clearance of the flow field structure is analyzed and the numerical results and model experimental results which confirmed the method can basically reflect the internal flow of the turbine are compared． The results show that with the reduction of the cavitation coefficient，the energy of the water turbine characteristics change，and hydraulic performance degraded too． And the arrival of the critical cavitation coefficient leads to efficiency to drop significantly; affected by the occurrence of cavitation intensification，pressure fluctuation amplitude is increased in the suction side，and the nearby flange of the amplitude is greater than that in the middle part of the blade and hub． When the partial pressure drops below the saturation pressure，fluctuation is no longer violent，with the phenomenon called“clipping”appearing． With the tip clearance value and cavitation occurrences aggravating in the gap，cavitation shape evolves from a gap cavitation to an airfoil one，and then leakage vortex cavitation emerges． The rotating frequency dominates the pressure fluctuation of the nearby flange on the suction side of the blade，a larger tip clearance can reduce high frequency pressure fluctuation at the flange，leakage flow will lead to more severe cavitation． Therefore，selecting the appropriate value gap is greatly significant to the bulb turbine in stable operation，lower vibration and noise．