A large amount of experimental work has been carried out in the past tounderstand mean and fluctuating forces on a single circular cylinder in cross flows. In comparisonsubstantially less work can be found on the inte...A large amount of experimental work has been carried out in the past tounderstand mean and fluctuating forces on a single circular cylinder in cross flows. In comparisonsubstantially less work can be found on the interference between multiple cylinders and the numberof publications a-vailable becomes drastically smaller as the number of cylinders involvedincreases. The current experimental work systematically examines the wake shielding effects of threecylinders in a towing tank. Though staggered, the three cylinders are arranged mainly along theflow direction with the downstream cylinders situating in the wakes of the upstream cylinders. Thetests are mainly carried out in the sub-critical Reynolds number regime with the upper end close tothe critical Reynolds number regime. Significant drag reduction on downstream cylinders isidentified.展开更多
In his paper, the frequency of vortex shedding from three cylinders of the same diameter in equilateral triangular arrangement is determined experimentally by the spectrum analysis of surface pressure fluctuations at ...In his paper, the frequency of vortex shedding from three cylinders of the same diameter in equilateral triangular arrangement is determined experimentally by the spectrum analysis of surface pressure fluctuations at a Reynolds number of 3.0×10 4. For α=0°, there exists ‘bistable’ flow at the spacing 2.0. For α=30°, the vortex shedding of the front cylinder is found at small spacing less than 2.0. It is quite different from the case of two cylinders in tandem arrangement only. The side cylinder has great effects on the flow between the other two cylinders in close arrangement. For α=60°, there exists a critical spacing of about 2.5 that the frequency of each cylinders is nearly half of f s below this spacing and equal to f s above it respectively. The interference among three cylinders was negligible in the spacing range above 3.0 at α=0 and 60 deg., and each cylinder behaves as a single cylinder with the same vortex shedding frequency f s. In these small spacing (spacing<3.0), interference occurs seriously and has great effects in a complex fashion on the flow state around three cylinders.展开更多
文摘A large amount of experimental work has been carried out in the past tounderstand mean and fluctuating forces on a single circular cylinder in cross flows. In comparisonsubstantially less work can be found on the interference between multiple cylinders and the numberof publications a-vailable becomes drastically smaller as the number of cylinders involvedincreases. The current experimental work systematically examines the wake shielding effects of threecylinders in a towing tank. Though staggered, the three cylinders are arranged mainly along theflow direction with the downstream cylinders situating in the wakes of the upstream cylinders. Thetests are mainly carried out in the sub-critical Reynolds number regime with the upper end close tothe critical Reynolds number regime. Significant drag reduction on downstream cylinders isidentified.
文摘In his paper, the frequency of vortex shedding from three cylinders of the same diameter in equilateral triangular arrangement is determined experimentally by the spectrum analysis of surface pressure fluctuations at a Reynolds number of 3.0×10 4. For α=0°, there exists ‘bistable’ flow at the spacing 2.0. For α=30°, the vortex shedding of the front cylinder is found at small spacing less than 2.0. It is quite different from the case of two cylinders in tandem arrangement only. The side cylinder has great effects on the flow between the other two cylinders in close arrangement. For α=60°, there exists a critical spacing of about 2.5 that the frequency of each cylinders is nearly half of f s below this spacing and equal to f s above it respectively. The interference among three cylinders was negligible in the spacing range above 3.0 at α=0 and 60 deg., and each cylinder behaves as a single cylinder with the same vortex shedding frequency f s. In these small spacing (spacing<3.0), interference occurs seriously and has great effects in a complex fashion on the flow state around three cylinders.
