Velocity and turbulence measurements downstream of flow conditioners

The flow downstream of three conditioners, a tube bundle and two perforated plates, is investigated experimentally by means of particle image velocimetry and hot wire anemometry for Reynolds numbers of the order 10⁵. The conditioners are exposed to the flow disturbed by two different installations: a 90° single bend and a 2×90° out-of-plane double bend. Velocity profiles, turbulent fluctuations and Reynolds‘ stress are measured. The jets issuing from the holes and tubes of the conditioners are visualised in the near field which extends up to approximately four pipe diameters downstream of the conditioners. The disturbance imposed on the flow by the conditioners disappears at this position, while the decay of the disturbance caused by the installations takes place in the far field. The decay rate in the far field depends on the specific installation. It is found that this decay is more rapid for the double bend. While the velocity profiles match the profile for fully developed flow approximately at a position of 25 diameters downstream of the conditioners, the turbulent equilibrium state is not even reached at 50 diameters. The results also show that the perforated plates have a higher efficiency than the tube bundle in conditioning the disturbed flow.