Transient Behavior of Complex Aeraulic or Hydraulic Networks Including Centrifugal Fans or Pumps

The prevision of the transient behavior of aeraulic or hydraulic networks subject to sudden pressure changes at their extremities and/or including centrifugal fans or pumps with discontinuous operations is an inescapable topic with regard to active control developments. The knowledge of the unsteady behavior of eventual centrifugal fans/pumps located inside the different circuits subject to flow rate variations is essential due to their creative or dissipative energy transient behavior. Assuming incompressibility for the fluid flow, a theoretical model is set up taking into account simultaneously the transient behavior of several aeraulic circuits (integral kinetic energy theorem applied to a geometrical discrete decomposition) and that of the associated centrifugal fans (modeling of motor and resistant torque and coupling with rotor inertia), both being coupled by the power supplied by the fan to the fluid. Experimental measurements obtained from a single pipe equipped with a fan and from a real aeraulic network show the model validity provided the flow does not reverse in the fans, even if the fluid is assumed incompressible.