The use of blowing flow control to reduce bluff body interaction noise

Angland, D., Zhang, X. and Goodyer, M. (2010) The use of blowing flow control to reduce bluff body interaction noise. In 16th AIAA/CEAS Aeroacoustics Conference (31st AIAA Aeroacoustics Conference). American Institute of Aeronautics and Astronautics.. (doi:10.2514/6.2010-3786).

Abstract

When an unsteady wake from an upstream body impinges on a downstream body, the resultant interaction noise can be significant. The use of distributed blowing through the surface of a cylinder to reduce this source of noise was investigated in a series of experiments. The two bluff bodies in tandem were a cylinder and an H-beam. Two configurations were tested, one with the cylinder upstream of the H-beam (OH configuration) and the other with the H-beam upstream of the cylinder (HO configuration). The default separation distance was x/φ = 2. These two configurations modelled the interaction noise due to large perturbations in the wake generated by an upstream component inducing unsteady pressure fluctuations on a downstream component. Blowing was used to break down the large flow structures in the wake and to modify the shear layers. The mean velocities and velocity fluctuations were determined in the flowfield. The application of blowing to the OHconfiguration reduced the u'u' component of the stress term. This resulted in a peak reduction of 9.3 dB at a Strouhal number of 0.2. There was a broadband noise reduction of 3.2 dB averaged over the frequency range 0.05 < St < 5. The effect of blowing on the HO configuration was to inhibit the strong crossflow fluctuations (w'w') between the H-beam and the cylinder by delaying the reattachment of the shear layers onto the surface of the cylinder. This resulted in a large noise reduction of 13.2 dB at a Strouhal number of 0.8. There was a broadband noise reduction of 4.3 dB averaged over the frequency range 0.05 < St < 6.3. The effect of blowing produced additional high frequency noise. This additional noise was minimised with blowing applied through a sintered plate with a very small pore diameter.

This record has no associated files available for download.

Contributors

Author: D. Angland

Download statistics