Swirl generator

Swirl generator is a special device which mimics the flow in hydraulic turbine at part load conditions. The device is designed with two rows of blade: the guide vane (blue) which generate the swirling flow and the runner (green) which rotate freely at runaway speed balancing the total pressure from hub to shroud. As a result, a swirling flow configuration with self-induced instability is generated in conical section. The flow configuration is deeply investigated to understand the swirling flow physics. Several flow control methods have been developed and tested on this test rig (e.g. axial water injection, flow feedback, adjustable diaphgram,pulsating water jet, air admission and magneto-rheological control).  Magneto-rheological brake (MRB) was specially designed in order to control the swirling flow configuration. MRB was designed considering the geometrical constrains imposed by actual configuration. MRB device includes iron housing, coil, seals and bearing and the magneto-rheological fluid. MRF is located in a gap betwen rotating and fixed parts in the iron house. The basic principle of this device consists of applying a magnetic field on MRF that changes its vicosity. As a result, the apparent viscosity of MRF is increased leading to slow down the runner speed. In our investigations, the runner speed is slow down from 1020 rpm (runaway speed) to 690 rpm.