小流量工况下尾水管压力脉动抑制OA

In hydro-wind-solar hybrid power generation systems,mixed-flow turbines are required to operate over a broader load range and greater operational flexibility.To mitigate the pressure pulsations within the draft tube under low-load conditions,a three-dimensional full flow path numerical simulation of a giant mixed-flow turbine was conducted using the DES turbulence model.The analysis focused on the vortex rope characteristics within the draft tube at 37.8％load and the internal mechanism of pres-sure pulsation suppression by draft tubes with wave-shaped generatrix and two different protrusion heights were analyzed.The results indicate that the wave-shaped generatrix draft tube can truncate wall vortices and improve the flow state at the draft tube inlet,significantly reducing the amplitude of the pressure pulsations on the draft tube wall,with a maximum reduction of 25.00％.Additionally,it sup-presses upstream-propagating pressure pulsations caused by the wall-attached vortices.Due to the in-creased energy loss caused by the geometric modification of the draft tube,the efficiency decrease re-mains within 0.73 percentage point.Moreover,the study shows that units equipped with wave-shaped generatrix draft tubes exhibit faster attenuation of pressure pulsation amplitude due to the rotor-stator interaction at the draft tube inlet wall,with a maximum reduction reaching 69.98％.