Experimental Investigation of the Frequency Spectra of Vortex Shedding from a Triangular Bluff Body at Different Flow Angles

Document Type : Research Article

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Department of Mechanical Engineering, Iranian Research Organization for Science and Technology (IROST), Tehran, Iran

Abstract

The base of the vortex flowmeter is the linear relationship ( is a constant and is vortex shedding frequency). Therefore, the accuracy of the flow meter is only a function of the vortex shedding frequency measurement accuracy. To determine the frequency measurement accuracy, it is necessary to investigate its frequency spectrum. In this research, vortex shedding and its frequency spectrum downstream of an equilateral triangular model of 10 mm side have been investigated experimentally in a closed-type wind tunnel using a hot-wire anemometer. The vortex shedding frequency spectra were fitted using the normal Gauss distribution, and based on the expected confidence level, the accuracy of the frequency measurement was evaluated and its changes were quantified using the standard deviation of the normal distribution. Results show for Re >1200, the Strouhal number variation is independent of the Re number, and it is only a function of the flow angle. Also, for a 95% confidence level, the maximum frequency measurement error for the triangular model is 1.53% for , and 2.46% for . The standard deviation of the frequency spectra has an increasing trend streamwise, however, it is constant spanwise outside the wake region. When the flow angle is in the range of , the measurement error increases to about 9%.

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Amirkabir Journal of Mechanical Engineering
Volume 56, Issue 5
2024
Pages 679-698

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