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Pressure measurements for rigid models fail to take aeroelastic effects into account, as well as forced vibration tests only consider the effect of an oscillating model on wind flow and cannot include the feedback from wind flow to the oscillating model. To investigate the characteristics of unsteady aerodynamic forces and predict the aeroelastic response of a tapered prism during VIV–galloping, hybrid aeroelastic-pressure balance (HAPB) wind tunnel tests at different reduced wind velocities were carried out. Unsteady pressures and tip responses of a tapered test model were synchronously observed. Both the aerodynamic and aeroelastic characteristics of the tapered prism during VIV–galloping instability were discussed in terms of aeroelastic response, force spectrum, coherence coefficient and pressure distribution. Subsequently, the VIV–galloping response was predicted by unsteady aerodynamic forces and compared to quasi-static calculations and experimental results. It was found that large-amplitude periodic vibrations took place at approximately twice the onset wind speed of VIV, which was recognized as VIV–galloping. Moreover, structural oscillation would have a significant effect on aerodynamic characteristics in the crosswind direction. In addition, the HAPB test was efficacious in measuring unsteady aerodynamic forces on the test model, which were effective to predict VIV–galloping instability of bluff bodies. [ABSTRACT FROM AUTHOR]

Wind tunnel tests have become one of the most effective ways to evaluate aerodynamics and aeroelasticity in bluff bodies. This paper has firstly overviewed the development of conventional wind tunnel test techniques, including high frequency base balance technique, static synchronous multi-pressure sensing system test technique and aeroelastic test, and summarized their advantages and shortcomings. Subsequently, two advanced test approaches, a forced vibration test technique and hybrid aeroelastic- force balance wind tunnel test technique have been comprehensively reviewed. Then the characteristics and calculation procedure of the conventional and advanced wind tunnel test techniques were discussed and summarized. The results indicated that the conventional wind tunnel test techniques ignored the effect of structural oscillation on the measured aerodynamics as the test model is rigid. A forced vibration test can include that effect. Unfortunately, a test model in a forced vibration test cannot respond like a structure in the real world; it only includes the effect of structural oscillation on the surrounding flow and cannot consider the feedback from the surrounding flow to the oscillation test model. A hybrid aeroelastic-pressure/force balance test technique that can observe unsteady aerodynamics of a test model during its aeroelastic oscillation completely takes the effect of structural oscillation into consideration and is, therefore, effective in evaluation of aerodynamics and aeroelasticity in bluff bodies. This paper has not only advanced our understanding for aerodynamics and aeroelasticity in bluff bodies, but also provided a new perspective for advanced wind tunnel test techniques that can be used for fundamental studies and engineering applications.

Tapering is a common morphological modification to ensure the stability of civil structures, especially as more and more high-rise buildings push the skyline of modern cities. However, the aerodynamics, aeroelasticity, and fluid-structure-interaction of tapering remain far from been fully understood. Through wind tunnel tests, the present work offers some notable observations on the effects of tapering, specifically considering different wind attack angles, wind velocities, and structural rigidities. A novel phenomenon unique to tapering is discovered and termed as partial reattachment. It depicts the partial reattachment of a shear layer onto a tapered structural face, which suppresses vortex shedding in reattached regions and forms a separation envelope. It also propagates from structural base to the free end with an increasing wind attack angle, and ultimately transforms into complete reattachment. Consequently, behavioral bi-polarities in force, vortex shedding characteristics, and cross-point correlation are observed. Aeroelastically, tapering promotes the unsteady effect and the VIV-galloping interaction near the free-end, making the prism more susceptible to wind-induced vibrations. With aeroelasticity, partial reattachment also introduces a discontinuous vortex shedding phenomenon, which is subjected to an intensity demarcation. • Characteristics of unsteady aerodynamic forces on the tapered prism were investigated at different wind attack angles. • Aeroelasticity of the tapered prism was investigated at different reduced velocity. • A novel phenomenon named partial reattachment was reveled. • The quasi-steady theory fails to predict the tip responses of the tapered prism. [ABSTRACT FROM AUTHOR]

Wind tunnel tests have become one of the most effective ways to evaluate aerodynamics and aeroelasticity in bluff bodies. This paper has firstly overviewed the development of conventional wind tunnel test techniques, including high frequency base balance technique, static synchronous multi-pressure sensing system test technique and aeroelastic test, and summarized their advantages and shortcomings. Subsequently, two advanced test approaches, a forced vibration test technique and hybrid aeroelastic- force balance wind tunnel test technique have been comprehensively reviewed. Then the characteristics and calculation procedure of the conventional and advanced wind tunnel test techniques were discussed and summarized. The results indicated that the conventional wind tunnel test techniques ignored the effect of structural oscillation on the measured aerodynamics as the test model is rigid. A forced vibration test can include that effect. Unfortunately, a test model in a forced vibration test cannot respond like a structure in the real world; it only includes the effect of structural oscillation on the surrounding flow and cannot consider the feedback from the surrounding flow to the oscillation test model. A hybrid aeroelastic-pressure/force balance test technique that can observe unsteady aerodynamics of a test model during its aeroelastic oscillation completely takes the effect of structural oscillation into consideration and is, therefore, effective in evaluation of aerodynamics and aeroelasticity in bluff bodies. This paper has not only advanced our understanding for aerodynamics and aeroelasticity in bluff bodies, but also provided a new perspective for advanced wind tunnel test techniques that can be used for fundamental studies and engineering applications. [ABSTRACT FROM AUTHOR]