Research of key technology for turbine efficiency measurement based on thermodynamics method

Abstract

As it is difficult to get the absolute water discharge, from which we can calculate the turbine efficiency, the thermodynamic method is proposed as an effective and more precise method for higher than 100 meters’ water head turbine. In which method, the water temperatures of inlet of spiral case and outlet of draft tube are measured and the flow discharge can be calculated according to the first law of thermodynamics. In the paper, with the practice and field test experience in several plants, some key technology and difficulties for thermodynamic method are discussed, which including advanced structure design and optimize for high pressure water sampling vessel, which can avoid the pipe crack or water leakage by reducing the connecting bolts and adding supporting bars, and a measuring frame in the draft tube flow channel, which using only one thermometer but can meet the requirement of IEC regulation; at last, for resolving the problem of flow velocity measurement in low pressure section, an iteration calculation method is brought out, and the field test data shows the method can get a good result for replacing the current meter method.