Measurement of Velocity and Turbulence Downstream of Flow Conditioners

Particle-image velocimetry and hot-wire anemometry are used for experimentally studying the flow downstream of three conditioners, a tube bundle and two perforated plates at Reynolds numbers of the order 10. 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 to approximately four pipe diameters downstream of the conditioners. At that position the disturbance imposed on the flow by the conditioners disappears, 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. While the velocity profiles match the profile for fully developed flow at a position of approximately 25 diameters downstream of the conditioners, the turbulent equilibrium state is not reached even at 50 diameters. The results also show that the perforated plates have a higher efficiency than the tube bundle in conditioning the disturbed flow.