阻抗孔位置及直径对含长连接管调压室阻抗特性和三维流场影响研究

Study on Influence of Position and Diameter of Throttled Orifice on Impedance Characteristics and Three-dimensional Flow Field of Surge Tank with Long Connecting Pipe

含长连接管的调压室可通过在连接管内设置小于其管径的阻抗孔来增强调压室的阻抗特性。为研究长连接内阻抗孔的位置及直径两种因子对此类调压室阻抗特性的影响规律,以水头损失系数和流量系数为优化目标,以位置和直径为优化变量,基于正交优化设计方法和CFD数值模拟软件,计算分析了各组合方案下的调压室阻抗系数和三维流场的变化规律。结果表明,阻抗孔前后水流湍流强度增幅明显,距离连接管两端端部越近,对调压室大井和管道系统内流场影响程度越大;当阻抗孔位于连接管顶部与调压室大井连接处,可最大程度发挥阻抗孔的阻抗效果,以阻抗孔与连接管管径比0.8为例,水头损失系数增幅约30%;连接管直径增大有效降低调压室局部流场压强最值浮动范围;阻抗孔位于靠近连接管顶部且不在大井连接处时,水流流出调压室时连接管及下游隧洞总体湍流强度较小,流场更稳定。

The impedance characteristics of a surge tank with a long connecting pipe can be enhanced by setting a throttled orifice smaller than its diameter in the connecting pipe.In order to study the influence law of the position and diameter of the throttled orifice in the long connection on the impedance characteristics of such a surge tank,the head loss coefficient and flow coefficient were taken as optimization objectives,and the position and diameter were taken as optimization variables.Based on the orthogonal optimization design method and CFD numerical simulation software,the variation law of the impedance coefficient of the surge tank and the three-dimensional flow field under each combination scheme was calculated and analyzed.The results show that the turbulence intensity increases obviously before and after the impedance hole,and the closer the distance between the two ends of the connecting pipe,the greater the influence on the flow field in the surge tank well and pipeline system is.When the impedance hole is located at the connection between the top of the connecting pipe and the big well of the surge tank,the impedance effect of the impedance hole can be maximized.Taking the 0.8 diameter ratio of the impedance hole to the connecting pipe as an example,the water head loss coefficient increases by about 30%.The maximum floating range of local flow field pressure in the surge tank can be effectively reduced by increasing the diameter of the connecting pipe.When the impedance hole is located near the top of the connecting pipe and not at the big well joint,the overall turbulence intensity of the connecting pipe and the downstream tunnel is smaller and the flow field is more stable when the water flows out of the surge tank.