Elham Ameri - Department of Chemical Engineering, Shahreza Branch, Islamic Azad University, Shahreza,Iran.

Turbulent air flow through a ninety degree bend under external low frequencies of 1.5 and 3 Hz was investigated experimentally by using Hot Wire Anemometer. The bend had a diameter of 106mm and a curvature radius ratio of 6.0 with long, straight upstream and, downstream pipes. In theexperimental study, The Measurements were performed for air flow rate with the bulk mean velocity of 10.97 m/s that corresponds to Reynolds number of 31200, for the standpoints of radialand axial velocity. In the Inlet plane of the bend due to the pressure gradient generated in the longitudinal direction of the bend, the Maximum velocity appeared toward the inner wall of the bend. The Maximum velocity was seen off-center at the inlet plane of the bend, showing the strongeffect of bend downstream. At the outlet plane of the bend the velocity profile flattened due to extra mixing induced in the flow by oscillation

Oscillation, Bend, Velocity, Air flow, Turbulent