多出水口蓄水池的三维数值模拟

本文运用FLUENT软件对不规则蓄水池在3种不同流量下的水流流场进行了数值模拟，得出 不同流量下流场中不同点沿水深方向的流速分布，并将数值计算结果与物理模型实验结果进行比较， 发现两者比较吻合。表明:FLUENT软件模拟不规则蓄水池水流流场是基本可行的。

Comparison and application of calculation method for stability against external pressure of stiffening ring for embedded steel penstock

For the analysis of the stability against external pressure of the stiffening ring for the embedded steel penstock，the commonly used calculation methods at home and abroad include Amstutz method，Jacobsen method and the strength formula specified in the“Design Code for Steel Penstocks of Hydroelectric Stations”( NB/T 35056—2015) ( hereinafter referred to as the code) . The three calculation methods are comparatively analyzed herein，and then the conclusion is obtained as the follows: the critical external pressures calculated by both Amstutz formula and Jacobsen formula are decreased along with the increase of the value of gap，however，the influence from the value of gap is not considered in the strength formula specified in the code，from which the critical external pressure obtained from the calculation is not related to the value of gap. All the critical external pressures obtained from the three calculation methods are increased along with the increases of the height of stiffening ring，the thickness of pipe-wall and the yielding strength of the steel material and are decreased along with the increase of the spacing among the stiffening rings. The critical external pressure of the stiffening ring obtained from the calculation made by the strength formula specified in the code is less than those obtained from both Amstutz formula and Jacobsen formula，and then the adoption of the strength formula specified in the code is obviously more conservative when the external water head is less than 130 m. Through the relevant comparative analysis，it is suggested to take Jacobsen method as one of the main methods for the calculation of the stability against external pressure of the stiffening ring for the embedded steel penstock specified in the relevant steel penstock design code in China.