中文摘要：

基于托马假设条件,并考虑了明满流尾水系统中的水位波动对电站机组稳定性的影响,推导了含明满流的尾水调压室稳定断面面积计算公式.由该公式计算得到的调压室断面面积分为两部分：第一部分调压室断面面积为下游低水位对应的调压室稳定断面面积;第二部分调压室断面面积为满流时对应的调压室稳定断面面积,其洞身沿高度方向呈倒喇叭型.这种结构既减小了调压室的开挖工程量,又降低了调压室结构支护难度.该公式与托马稳定断面面积公式相似,方便实用,并经过工程实例验证了其合理性、经济性和安全性,可用于实际工程设计.

英文摘要：

Based on Thomas assumption and considering the influence of water level fluctuation of free-surface-pressurized flow on the stability of units,stable sectional area calculation formula of tailrace surge tank with free-surface-pressurized flow was deduced.Calculated by the formula,sectional area of tailrace surge tank was consists of two parts：one was corresponded to the low water level and the other was to the full flow.The shape of the surge tank along the elevation direction was like an inverted horn,not only reduced the amount of excavation but also reduced the difficulty of structure supporting.What＇s more,it is similar to the Thomas formula and convenient to use.Through the simulation of a project,the formula deduced was validated with rationality,economy and safety,which can be used for the practical engineering design.