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Added Mass Coefficient
The Experts below are selected from a list of 3801 Experts worldwide ranked by ideXlab platform
Shuqi Wang – One of the best experts on this subject based on the ideXlab platform.
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Study of the hydrodynamic performance prediction method for a horizontal-axis tidal current turbine with coupled rotation and surging motion
Renewable Energy, 2019Co-Authors: Shuqi Wang, Ren-chuan Ye, Zhong-fei Chen, Liang ZhangAbstract:Abstract For the fast prediction of the hydrodynamic characteristics of a floating horizontal-axis tidal current turbine (HATT) with coupled rotation and surging motion, this study applies the CFD method to simulate the coupled rotation and surging motion, and obtains the axial force and axial torque Coefficients at different current velocities. According to the CFD simulation data, the constant force, damping, and Added Mass Coefficients can be obtained by least-squares fitting. The approximate calculation formulas of the axial force and axial torque Coefficients of a turbine with coupled rotation and surging motion are summarized by analyzing the constant force, damping, and Added Mass Coefficients under different surge frequencies and amplitudes, turbine rotation speeds, and current velocities. The results demonstrate the following: 1) the frequency and amplitude of the surge have little impact on the damping Coefficient, which is positively proportional to the tip speed ratio; 2) when predicting the hydrodynamic load of a turbine with coupled rotation and surging motion, the Added Mass Coefficient can be neglected, and only the influence of the constant terms of the constant force and the damping Coefficients are needed. The approximate calculation formula obtained in this study can effectively predict the hydrodynamic load of the HATT.
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the effects of roll motion of the floating platform on hydrodynamics performance of horizontal axis tidal current turbine
Journal of Marine Science and Technology, 2017Co-Authors: Shuqi Wang, Jianhua Zhang, Liang ZhangAbstract:Under the condition of actual sea state, hydrodynamic characteristics of floating horizontal-axis turbine are related to wave characteristics and floating carrier motion responses. We recently published the hydrodynamic performance and axial damping Coefficient of the horizontal-axis tidal current turbine influenced by surge motion in constant inflow using CFD simulation (Zhang et al. Renew Energy 74:796–802, 2015). Encouraged by this result, this paper uses sliding mesh to analyze the hydrodynamic characteristics in uniform stream when the turbine is forced to roll and studies influences of different roll frequency, roll amplitude, and tip speed ratio on turbine’s performance. Roll-damping Coefficient and Added Mass Coefficient can be derived by torque almanacs curve of rolling turbine by the least square method. Results show that the turbine axial load, roll moment, and energy utilization ratio will fluctuate in roll motion; the more roll frequency and roll amplitude, and the more load and moment wave amplitude of momentary value. The crest value occurs in the balance position of rolling, while the amplitude of oscillation depends on the angular speed of rolling and rotating speed of the turbine. The frequency and amplitude of the roll have little impact on damping Coefficient, but rotational speed of the turbine has positive impact on this Coefficient. Results of this study can provide data to study motion response of floating carrier for floating tidal current turbine system and check the structural design and control of the electric output.
Liang Zhang – One of the best experts on this subject based on the ideXlab platform.
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Study of the hydrodynamic performance prediction method for a horizontal-axis tidal current turbine with coupled rotation and surging motion
Renewable Energy, 2019Co-Authors: Shuqi Wang, Ren-chuan Ye, Zhong-fei Chen, Liang ZhangAbstract:Abstract For the fast prediction of the hydrodynamic characteristics of a floating horizontal-axis tidal current turbine (HATT) with coupled rotation and surging motion, this study applies the CFD method to simulate the coupled rotation and surging motion, and obtains the axial force and axial torque Coefficients at different current velocities. According to the CFD simulation data, the constant force, damping, and Added Mass Coefficients can be obtained by least-squares fitting. The approximate calculation formulas of the axial force and axial torque Coefficients of a turbine with coupled rotation and surging motion are summarized by analyzing the constant force, damping, and Added Mass Coefficients under different surge frequencies and amplitudes, turbine rotation speeds, and current velocities. The results demonstrate the following: 1) the frequency and amplitude of the surge have little impact on the damping Coefficient, which is positively proportional to the tip speed ratio; 2) when predicting the hydrodynamic load of a turbine with coupled rotation and surging motion, the Added Mass Coefficient can be neglected, and only the influence of the constant terms of the constant force and the damping Coefficients are needed. The approximate calculation formula obtained in this study can effectively predict the hydrodynamic load of the HATT.
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the effects of roll motion of the floating platform on hydrodynamics performance of horizontal axis tidal current turbine
Journal of Marine Science and Technology, 2017Co-Authors: Shuqi Wang, Jianhua Zhang, Liang ZhangAbstract:Under the condition of actual sea state, hydrodynamic characteristics of floating horizontal-axis turbine are related to wave characteristics and floating carrier motion responses. We recently published the hydrodynamic performance and axial damping Coefficient of the horizontal-axis tidal current turbine influenced by surge motion in constant inflow using CFD simulation (Zhang et al. Renew Energy 74:796–802, 2015). Encouraged by this result, this paper uses sliding mesh to analyze the hydrodynamic characteristics in uniform stream when the turbine is forced to roll and studies influences of different roll frequency, roll amplitude, and tip speed ratio on turbine’s performance. Roll-damping Coefficient and Added Mass Coefficient can be derived by torque almanacs curve of rolling turbine by the least square method. Results show that the turbine axial load, roll moment, and energy utilization ratio will fluctuate in roll motion; the more roll frequency and roll amplitude, and the more load and moment wave amplitude of momentary value. The crest value occurs in the balance position of rolling, while the amplitude of oscillation depends on the angular speed of rolling and rotating speed of the turbine. The frequency and amplitude of the roll have little impact on damping Coefficient, but rotational speed of the turbine has positive impact on this Coefficient. Results of this study can provide data to study motion response of floating carrier for floating tidal current turbine system and check the structural design and control of the electric output.
Maurizio Porfiri – One of the best experts on this subject based on the ideXlab platform.
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A combined digital image correlation/particle image velocimetry study of water-backed impact
Composite Structures, 2019Co-Authors: Peng Zhang, Maurizio PorfiriAbstract:Abstract Several aeronautical and naval structures are routinely exposed to impulsive loading conditions that elicit complex fluid-structure interactions. An archetypal problem that has attracted considerable attention is the impact on a compliant plate, fixed on a water surface. Despite significant progress in mathematical modeling of the impact, several technical questions remain open due to the lack of a simultaneous experimental characterization of the structural response and fluid flow. Here, we seek to fill this gap of knowledge through the integration of digital image correlation (DIC) and particle image velocimetry (PIV). We employ DIC to measure the apparent in-plane displacement of the plate, from which we reconstruct its out-of-plane deflection. On the other hand, PIV is utilized to measure the velocity field of the water, from which we infer the pressure field in the fluid and the hydrodynamic loading on the plate. We examine a number of aggregated measures, including the mid-span deflection, strain energy stored in bending and stretching of the plate, modal contribution factors, hydrodynamic loading, and Added Mass Coefficient. Just as our approach constitutes a significant methodological step forward in the study of unsteady fluid-structure interactions, our experimental results contribute new evidence for an improved understanding of water-backed impact.
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a combined digital image correlation particle image velocimetry study of water backed impact
Composite Structures, 2019Co-Authors: Peng Zhang, Maurizio PorfiriAbstract:Abstract Several aeronautical and naval structures are routinely exposed to impulsive loading conditions that elicit complex fluid-structure interactions. An archetypal problem that has attracted considerable attention is the impact on a compliant plate, fixed on a water surface. Despite significant progress in mathematical modeling of the impact, several technical questions remain open due to the lack of a simultaneous experimental characterization of the structural response and fluid flow. Here, we seek to fill this gap of knowledge through the integration of digital image correlation (DIC) and particle image velocimetry (PIV). We employ DIC to measure the apparent in-plane displacement of the plate, from which we reconstruct its out-of-plane deflection. On the other hand, PIV is utilized to measure the velocity field of the water, from which we infer the pressure field in the fluid and the hydrodynamic loading on the plate. We examine a number of aggregated measures, including the mid-span deflection, strain energy stored in bending and stretching of the plate, modal contribution factors, hydrodynamic loading, and Added Mass Coefficient. Just as our approach constitutes a significant methodological step forward in the study of unsteady fluid-structure interactions, our experimental results contribute new evidence for an improved understanding of water-backed impact.
Pierluigi Mollicone – One of the best experts on this subject based on the ideXlab platform.
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Dynamic analysis of a floating hybrid spar tension leg platform concept for wind monitoring applications in deep sea
Iet Renewable Power Generation, 2017Co-Authors: Marisa Micallef, Tonio Sant, Pierluigi MolliconeAbstract:This study presents an investigation to assess the motions experienced by a floating hybrid spar-tension leg platform structure when supporting a wind-monitoring lattice tower in deep water conditions of the Central Mediterranean. The numerical study is based on the software package ANSYS® AQWA™. The structure supports a 30 m wind-monitoring tower as well as a LiDAR system. A parametric analysis was carried out for different geometrical and met-ocean conditions, and the simulations were restricted to regular (single frequency) wave and constant wind speed conditions only. The Morison formulation was used to resolve the hydrodynamic loads in a time domain. The study shows how the natural periods of the floating wind-monitoring mast structure decrease with increasing buoyancy-to-weight ratios. From the time-series simulations, it was evident that slender spars experience smaller displacements. This is a favourable result as it results in more reliable wind measurements taken by the cup-type anemometers. Finally, a sensitivity analysis was carried out to examine the variations of surge motion predictions resulting from deviations in the hydrodynamic Coefficients. It was observed that the platform surge motion is more sensitive to deviations in the Added Mass Coefficient than the drag Coefficient.
Miroslav Puncochar – One of the best experts on this subject based on the ideXlab platform.
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How to estimate Added Mass of a spherical cap body: Two approaches
Chemical Engineering Science, 2015Co-Authors: Marek C. Ruzicka, Miroslav Simcik, Miroslav PuncocharAbstract:An analogy is established between two different approaches for estimating the Added Mass Coefficient of a spherical cap body. These two originate from very different assumptions but yield very similar results. Here we try to explain why it is possible.