Proposition of Unique Pumping System with Counter-Rotating Mechanism

Abstract

Turbo-pumps have weak points, such as when the pumping operation becomes unstable in the rising portion of the head characteristics and/or the cavitation occurs under the intolerably low suction head. To overcome both weak points simultaneously, this article proposes a unique pumping system with counter-rotating mechanism, which consists of twostage impellers and a peculiar motor with double rotors. The front and the rear impellers are driven by the inner and the outer rotors of the motor, respectively, keeping the relative rotational speed constant and counter-balancing the rotational torque. Such driving conditions not only smartly improve the unstable performance at lower discharge, but also suppress the cavitation at higher discharge, in the optimum cooperation with the impeller works and the rotor outputs.

The contribution of low‐head pumped hydro storage to grid stability in future power systems

“…They found that a trade-off relation exists between pump and turbine mode performances [15]. Kinemoto et al propose a pump system with a smart control CR mechanism, which can improve the unstable performance region and cavitation performance compared to a conventional singlestage impeller pump [14]. Next to the discussed shaft-driven concepts, rim-driven concepts can be an interesting opportunity because of their compactness and flexibility for installation [16].…”

Multiobjective Optimization of a Counterrotating Type Pump-Turbine Unit Operated at Turbine Mode

“…The advantages of this counterrotating technique were demonstrated already by many researchers [4][5][6]. Add to this Kanemoto and Oba [7] have invented the unique double rotational armatures coupled with the counterrotating type impellers or runners to suppress the unstable performance and cavitation throughout the entire operation region. They have called such features "smart control" for thirteen years [8].…”

Optimized Blade Design of Counter-Rotating-Type Pump-Turbine Unit Operating in Pump and Turbine Modes

“…As a result, the maximum hydraulic efficiency in the turbine mode is similar to one of the unit designed exclusively for the turbine mode. Kanemoto and Oba [7] invented unique double-rotational armatures coupled with the counter-rotating-type impellers/runners to suppress the unstable performance and cavitation throughout the operating region. Cao et al [8] studied the application of contra-rotating type rotors to reduce the rotational speed and pump size under the same specification of conventional axialflow pump through experimental and numerical methods.…”