Strain-gauge-based force transducers in hydrodynamic research
13 Jun 2001-Vol. 4317, pp 357-362
TL;DR: In this article, the authors present three typical resistance strain gauge based force transducers developed with specific requirements of hydrodynamic model testing and have been very useful in test which otherwise would have been impossible or uneconomical.
Abstract: This paper presents three typical resistance strain gauge based force transducers developed with specific requirements of hydrodynamic model testing and have been very useful in test which otherwise would have been impossible or uneconomical. The transducers presented include those for measuring single and multi-component forces and moments.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
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TL;DR: In this paper, the effects of marine growth on the hydrodynamic forces experimentally and determine the associated hydrodynamynamics coefficients were compared with the responses of a similar rigid cylinder fitted with marine growth.
Abstract: In this paper the wave induced hydrodynamic forces and the corresponding hydrodynamic coefficients for a 42 mm diameter model pipe subjected to regular waves was investigated experimentally and the results were compared with the responses of a similar rigid cylinder fitted with marine growth The main objective of this study was to quantify the effects of marine growth on the hydrodynamic forces experimentally and determine the associated hydrodynamic coefficients The experimental data were generated from a set of wave tank model tests and the results were scaled up using a scale factor of 1:55 The thickness of marine growth applied on the model pipe was varied with respect to the water depth in the ratio of 3:2:1 Regular waves were generated with wave heights ranging from 002 m to 0 2 m for modal period varying from 06 s to 325 s The tests were conducted for Keulegan-Carpenter number ranging from 39 to 233 The findings of the experimental results revealed that increasing the thickness of the full scale prototype cylinder by 110 mm due to marine growth fittings, has increased the overall wave hydrodynamic forces by 16 to 90% depending on the wave heights and the wave frequencies at which the model was tested, proving that the drag coefficients have considerably increased
6 citations
Cites methods from "Strain-gauge-based force transducer..."
...Details of the wave load sensor used in this study was published earlier by Idichandy [16]....
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TL;DR: In this article, the authors examined the hydrodynamic behavior of a tubular vertical cylinder with anode fittings subjected to regular waves in the wave basin of Universiti Teknologi PETRONAS.
Abstract: This paper examines the hydrodynamic behavior of a tubular vertical cylinder with anode fittings subjected to regular waves. The model experiments were carried out in the wave basin of Universiti Teknologi PETRONAS. The model was made from galvanized steel, with outer diameter Do= 0.034 m and total length l = 1.23 m, fixed vertically to the soffit of the wave tank bridge, and the free end was immersed in the wave tank to form a cantilevered beam with wetted length of 0.85 m. Overall, seven anodes were welded to the wetted length of the tubular cylinder, at a center to center spacing of 0.12 m. The model was subjected to regular wave with Hmax varying from 0.1 m to 0.2 m, with wave height increment of 0.05 m, and the time period varying from T = 1 s to 3 s. The tests were conducted for Keulegan-Carpenter number ranging from 3.9 to 23.3. The hydrodynamic forces and the corresponding hydrodynamic coefficients of the smooth cylinder were compared with the force responses of a tubular cylinder with the same outer diameter, fitted with anodes. A scale factor of 1:55 was adopted in this experimental study based on the limitations of the maximum water depth in the wave tank, and the scaled up force responses of the full scale prototype were analyzed and discussed. The results show that, installation of anodes has increased the drag coefficients by up to 20% depending on the wave frequencies at which the model was tested.
5 citations
Cites methods from "Strain-gauge-based force transducer..."
...Detail of the load sensor used in this study was published earlier by Idichandy [15]....
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07 Aug 2014
TL;DR: In this article, the effects of neighboring cylinders, spacing between the pipes, wave frequency and wave amplitude on the hydrodynamic coefficients of tubular cylinders were analyzed, and the obtained inertia and drag coefficients are in fair agreement with API and PTS specifications.
Abstract: Hydrodynamic coefficients for groups of tubular cylinders subjected to regular waves were experimentally investigated in this study. The experiments were carried out at Universiti Teknologi PETRONAS wave tank. The experimental hydrodynamic forces on tubular cylinders were measured using wave force sensors, while the theoretical values were estimated using Morison equation. The effects of neighboring cylinders, spacing between the pipes, wave frequency and wave amplitude on the hydrodynamic coefficients of tubular cylinders were analyzed. In this study, the model cylinders were fixed to the soffit of the wave tank bridge as cantilevered beams. The tubular cylinders covered in this study are 1.23 m long galvanized steel pipes with 34 mm diameter and 2.5 mm wall thickness. The immersed length of the cylinder was 850 mm. The pipes were subjected to regular waves with maximum wave height of 100 mm, and the KeuleganCarpenter number (KC) varied from 9.25 to 14.97. The obtained inertia and drag coefficients are in fair agreement with API and PTS specifications.
5 citations
TL;DR: In this article, the authors investigate the variation of forces and force coefficients acting on circular cylinders, which are arranged in a linear array along the direction of the waves, and demonstrate the significant modification of the forces on cylinders when they are present in a cylindrical array.
Abstract: The present investigation aims to experimentally determine the variation of forces and force coefficients acting on circular cylinders, which are arranged in a linear array along the direction of the waves. Most commonly used structural and non-structural elements in the construction of offshore platforms are circular cylindrical members. In many cases, these members are found in very close neighbourhood of each other, thus modifying the surrounding flow and wave forces acting on them. Model tests were conducted in the wave tank on a maximum of four cylinders of the same diameter. A reasonable scale factor was chosen considering the pertinent factors such as water depth, wave generating capability and accuracy of measurements. The cylinders were installed inside the wave tank as vertical cantilevers fixed at the top. Wave forces acting on the cylinders were measured using special wave force sensors exclusively designed and fabricated for the present project, while the wave profiles were recorded using wave probes installed in the wave basin. The results confirmed the presence of a force shielding effect on the trailing cylinders by the leading cylinders with few exceptions. The findings also substantiated the significant modification of the forces on cylinders when they are present in a linear array. A common practice adopted for the design of offshore platforms was identified with a possibility of underestimating the wave forces acting on the cylindrical elements. In many cases, the experimentally computed hydrodynamic force coefficients were found to be lower than the standard values adopted by various design codes. These findings portray the significance of the present work in achieving economy in the design of jacket platforms and risers.
4 citations
Cites background from "Strain-gauge-based force transducer..."
...Design details of the load cell were published in an earlier paper (Idichandy, 2001)....
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TL;DR: In this article, the wave forces recorded on circular cylinders present in different array configurations were investigated. But, the authors did not find any trend in variation of these forces, when the wave time periods, location of the cylinders in the array and the spacing between cylinders are varied.
Abstract: In this paper, major focus is given for determining the accurate wave forces recorded on circular cylinders present in different array configurations. Investigation is made to establish any trend in variation of these forces, when the wave time periods, location of the cylinders in the array and the spacing between cylinders are varied. Wave tank model tests were conducted in regular waves. Tandem cylinder configurations involving a maximum of four cylinders were considered for the present study. In addition to this, two linear arrays of four cylinders each, were installed side by side in the waves and the forces on each of the cylinders were determined. The spacing between the cylinders in this two dimensional array was varied and the trend in the variation of forces are presented. Change of transverse spacing between the cylinders was found to have more effect on the forces on cylinders, than the change in in-line spacing. The wave forces acting on singly existing cylinders were found to be less than that acting on individual cylinders present in the different array configurations considered. The variation of force coefficients with respect to the time periods was found to be of random nature. Morison equation is made use in the determination of these coefficients.
Cites background from "Strain-gauge-based force transducer..."
...Design details of the load cell were published in an earlier paper [8]....
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