Active noise cancellation applied to a centrifugal pump in a closed loop piping system
Johannes Büker, Andre Laß, Paul Werner, Frank–Hendrik Wurm
Abstract
The asymmetric velocity distribution of flow leaving the impeller vanes is causing pressure pulsations. The main reason for the pressure pulsations is the fluid dynamic interaction between the rotating impeller and the stationary casing. Therefor, the most significant pressure pulsations are related to the blade passing frequency and its harmonics. These pressure pulsations propagate as fluid-borne noise into the piping system and are exciting the structure of the piping system, which leads to undesirable vibrations and airborne noise emissions. If the pump speed changes dependent on the electrical grid frequency the pressure pulsation characteristics are effected as well. An active and adaptive reduction of the dynamic pressure pulsations by means of a specially developed hydrodynamic actuator is presented in this paper. Utilizing a feedforward active noise canceling (ANC) algorithm, the fluid-borne noise, the structural vibrations of the closed loop piping system and the airborne noise emission of a centrifugal pump could be reduced significantly.