抄録
In the present paper the attention is focused on the vortex shedding from the tubes in closely-arranged staggered tube banks. The tube banks were installed rigidly in the test section of the wind tunnel. We measured the spectrum, the coherence function, and the phase delay of velocity fluctuation as well as the gap velocity in the simulated tube banks which has same pitch ratio as that of a boiler heat exchanger. A single high peak at 231.3Hz was formed in the spectrum of the velocity fluctuation downstream the second low of the tube banks at mean gap velocity 23.1m/s. This peak frequency increased in proportion to the mean gap velocity. We found that this velocity fluctuation is caused by vortex shedding from the tube banks. As a result it was made clear that the symmetric pair of vortices were clearly formed even in the case of Reynolds number, based on mean gap velocity, about 0.7×10^5. Strouhal number, based on mean gap velocity and vortex shedding frequency, was 0.46.
