The influence of cylinders in tandem arrangement on unsteady aerodynamic loads

Abstract

This paper presents an experimental study on the unsteady pressure loading for two circular cylinders in tandem arrangement for the Reynolds number in the subcritical regime. Experiments were conducted on two heavily instrumented cylinders, each with multiple static and dynamic pressure sensor devices positioned at various peripheral and spanwise locations, enabling extensive dynamic surface pressure, coherence, and turbulence length-scale analysis. Results show that the root-mean-squared pressure magnitude of the pressure distribution results is much larger for the rear cylinder than for the front cylinder. In the case of small spacing ratios, the surface pressure density findings show a decreased shedding frequency on both cylinders, however the critical spacing ratio shows a quick jump in shedding frequency. The lateral coherence results also revealed that beyond the critical spacing, a prominent peak at the fundamental vortex shedding frequency exists, with weaker peaks at shedding harmonics on the front and rear cylinders, resulting in smaller correlation length values than those for smaller spacing ratios. The discovery of tonal peaks and their associated flow mechanics on cylinders in tandem were reinforced by the lift and drag power spectral density as well as the higher-order spectral analysis, such as wavelet analysis and persistence spectrum.