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液力透平内部流场的非定常压力脉动是影响机组运行稳定性的关键因素之一,为了研究液力透平蜗壳内部的压力脉动,采用流场分析软件对一单级液力透平内部流场进行了三维定常和非定常数值模拟,对蜗壳流道内不同周向位置、径向位置和不同流量时的压力脉动进行了时域和频域分析。结果表明:在一个叶轮旋转周期内蜗壳内压力的脉动数量等于叶片数;蜗壳入口位置和割舍位置处压力脉动较小,蜗壳环形部分中部和割舍前端位置处压力脉动较大;蜗壳内压力脉动的主频和次主频分别为叶频和2倍叶频;液力透平蜗壳内部的压力脉动程度在小流量下较小,随着流量的增加,压力脉动程度逐渐增加,大流量时最为剧烈。为了验证数值计算的准确性,建设了开式液力透平试验台,制造了模型样机对液力透平进行了外特性试验和非定常压力脉动测量,验证了数值计算的准确性。
The unsteady pressure pulsation in the internal flow field of the hydraulic turbine is one of the key factors that affect the stability of the unit. In order to study the pressure pulsation inside the turbine case, a single-stage hydraulic turbine The three-dimensional steady and unsteady numerical simulations of the internal flow field were carried out. The pressure fluctuations in different circumferential positions, radial positions and different flows in the scroll channel were analyzed in time and frequency domain. The results show that the number of pulsations in the volute is equal to the number of blades in one impeller rotation period, the pressure pulsation is small at the volute entrance and the place where the worm is seated, The main frequency and secondary frequency of internal pressure pulsation were leaf frequency and 2 times leaf frequency, respectively. The degree of pressure pulsation inside the turbine case was smaller under low flow rate. With the increase of flow rate, the degree of pressure pulsation gradually increased, The most intense flow when the most intense. In order to verify the accuracy of numerical calculation, an open hydraulic turbine test bed was built and a prototype was manufactured to test the external characteristics and unsteady pressure pulsation of the hydraulic turbine. The accuracy of the numerical calculation was verified.