水轮机热力学法测效率的改进方法  

Improved procedure to determine turbine efficiency by thermodynamic method

作　　者：曹登峰[1] 张鹏 周叶[1] 邹志超 CAO Dengfeng;ZHANG Peng;ZHOU Ye;ZOU Zhichao(China Institute of Water Resources and Hydropower Research,Beijing 100038;China International Water&Electric Corp.,Beijing 100120)

机构地区：[1]中国水利水电科学研究院,北京100038 [2]中国水利电力对外有限公司,北京100120

出　　处：《水力发电学报》2021年第10期105-111,共7页Journal of Hydroelectric Engineering

基　　金：中国水科院科研专项(HM0145B232020)。

摘　　要：水轮机效率测试中的热力学法通过对能量转换中单位能量的测定来确定水轮机的流量和效率,无需直接测量流量。开展热力学法时,低压侧断面流速分布不均是影响测试结果准确性的重要因素。针对此问题,提出了一种通过迭代计算水轮机低压侧流速、流量及效率的改进计算方法。该方法无需进行流速测量,减小了测试的工作量。引入单位机械能的修正项和低压侧流速进行双重迭代计算,得出的低压侧流速更能代表水轮机低压侧的平均流速,进而得到更准确的水轮机流量和效率。测试实例表明,迭代计算数次后,可得到准确的单位机械能、水轮机流量及效率,能够满足工程上的测试需要。此方法可促进热力学法在低水头型式水轮机效率测试中的应用和推广,值得予以借鉴。In determining turbine efficiency,the thermodynamic method obtains turbine discharge and efficiency through measuring specific energy per unit,with no direct measurement of discharge,but its accuracy is affected significantly by uneven velocity profiles at low-pressure sections.Focusing on this problem,this paper presents an improved iteration procedure to determine flow velocity at low-pressure sections,discharge and efficiency.It saves test work due to avoiding direct measurement of flow velocity.In the calculation procedure,we iterate the corrective terms of specific mechanical energy and flow velocity at the low-pressure sections,and obtain a final velocity that better represents the mean flow velocity at the low-pressure sections,so that the resulted efficiency is more accurate than direct measurement.Test results show that specific mechanical energy,turbine discharge and efficiency can be worked out by only several iteration steps,which can meet engineering test requirements,demonstrating the procedure is an improvement on the application of the thermodynamic method to low-head turbine measurements.

关 键 词：水轮机效率 热力学法 水轮机流量 冲击式水轮机 迭代计算 

分 类 号：TK730.7[交通运输工程—轮机工程]