Discussion on the Issues of Rotor-Stator Interference in Pump Turbine

Abstract

There are serious vibration issues of powerhouse in some pumped storage power plants and it affects severely the safe and stable operation of power plant. In order to settle the issues which have troubled the hydropower technology for several decades, extensive researches have been made. The rotor-stationary interference between rotating runner and stationary guide vanes are one of the researched issues concerned most and has the biggest influences. In this paper, the different opinions are presented. Firstly, the characteristics of pressure variations before and after the guide vanes are discussed and it indicates that, the pressure distribution is not uniform due to the turbulent flow around guide vanes but there is no pressure fluctuation with the dominant frequency of rotational frequency multiplying guide vane number. The interference precondition of pressure waves is there are two pressure waves with the same frequency, thus the new opinion, there is no rotor-stationary interference in the vaneless area, is presented. Secondly, equations of rotor-stationary interference presented by Hiroshi Tanaka and its derivation process are introduced. The equation foundation, physical meanings of parameters and equation dimensions are analyzed, and it is concluded that it is wrong to combine the pressure waves from rotating part and stationary part by multiplying the two pressure waves. And also the following mistakes and unreasonable issues are described. The studied objects are not consistent with that in practical application, the pump condition is not considered, the steady operation is taken as unsteady, and the definition of nodes is mistaken. The correct combination method of rotor-stationary interaction are presented.