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Dynamic performance optimization of a floating offshore wind turbine based on fractal-inspired design principles

ENERGY 2025年 324卷

作者： Huang, Haoda Liu, Qingsong Bashir, Musa Malkeson, Sean Li, Chun Yue, Minnan Miao, Weipao Wang, Jin Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China Univ Liverpool Sch Engn Brownlow Hill L69 3GH England Liverpool John Moores Univ Offshore & Marine LOOM Res Inst Liverpool Logist Byrom St Liverpool L3 3AF England

As the development of onshore and fixed offshore wind turbines approaches saturation, floating offshore wind turbines (FOWTs) are increasingly gaining attention due to their ability to operate in deeper waters and harness more stable wind resources. However, the dynamic responses of FOWTs are amplified significantly under the complex sea conditions, posing challenges to the overall system stability. This study proposes a novel semisubmersible platform featuring fractal structure inspired by Victoria Amazonica as solutions to the overall system stability of FOWTs. The computational fluid dynamics method, integrated with dynamic fluid-body interaction and volume of fluid wave model, is used to examine the aero, hydro, and mooring dynamics of the FOWT. A parametric model of the fractal structure with different branch levels is constructed by recursive method. Firstly, the hydrodynamic performance of the novel platforms with multi-level branch structures is examined under single wave conditions. The results show that vortices in fractal structures present higher velocity gradients and greater viscous dissipation, thereby effectively absorbing wave energy. The stability of the platform improves progressively as the branch levels increase. Subsequently, the dynamic responses of the fullconfiguration FOWT mounted on the platform with 8-level fractal structure (8LFS-FOWT) are further evaluated under wind-wave coupling conditions. The results reveal that 8LFS-FOWT achieves superior hydrodynamic performance with the most notable improvement in pitch amplitude of 25.22 % decrease. This enhancement also brings a 12.75 % reduction in the standard deviation of power output, forming positive feedback to ensure safe and stable operation of the system. The findings provide a valuable reference for promoting the innovative platform design of FOWTs.

关键词： Floating offshore wind turbine Leaf-vein structure Computational fluid dynamics Fractal dimension Fully coupled dynamic response

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Numerical Study on the Coupled Impact of Periodic Wake and Pulsating Jet on Film Cooling Efficiency on a Flat Wall

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APPLIED SCIENCES-BASEL 2025年第5期15卷 2558-2558页

作者： Peng, Qiushou Shi, Liuliu Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China

This paper presents a numerical study investigating the coupled effects of periodic incoming wake and pulsating jets on the film cooling efficiency of a flat wall. The sweeping frequency of the wake is maintained at a constant 10 Hz, while the blowing ratio (M) varies from 0.3 to 1. By adjusting the initial position of the rod, different phase lags are generated to assess the interaction between the incoming wake and the pulsating jet concerning film cooling efficiency. The results reveal that coupling the wake-affected surface with the low-blowing-ratio phase of the pulsating jet can effectively enhance film cooling efficiency at lower blowing ratios. Conversely, at higher blowing ratios, aligning the low-pressure phase of the pulsating jet at the film hole with the high-blowing-ratio jet pulsation results in an improved film cooling effect. Notably, when the phase lag (psi) is set to zero, the cooling efficiency of the pulsating film reaches its maximum across all blowing ratios, indicating an optimal coupling strategy.

关键词： wake pulsating jet film cooling coupling phase lag

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Simultaneous measurement of particle size distribution and mixing ratio based on Monte Carlo ultrasonic attenuation model

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MEASUREMENT SCIENCE AND TECHNOLOGY 2025年第2期36卷 026014-026014页

作者： Zhang, Shiwei Su, Geyi Niu, Gege Chen, Jingwen Su, Mingxu Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China

Mixed particle systems are commonly employed in industrial processes, where the characterization of particle size parameters and mixing ratio can frequently serve as key indicators in process control and production optimization. A Monte Carlo (MC) model was developed to numerically predict and study the ultrasonic attenuation spectrum characteristics in the polymethyl methacrylate (PMMA)-glass aqueous suspension, and together with the particle swarm optimization (PSO) algorithm, to handle the inverse problem in solving the particle size, distribution width, and mixing ratio. The results of the numerical simulations indicate that there exists a linear relationship between the attenuation coefficient and the mixing ratio, with the particle size exerting a significant influence. Furthermore, the multi-parameter simultaneous inversion also yielded calculation deviations of less than 1%, 3%, and 6% for the mixing ratio, characteristic diameter, and distribution width, respectively, in comparison to their given values. Afterward, a series of experiments were conducted to quantify the particle size and mixing ratio through the analysis of ultrasonic spectra. In spherical PMMA-glass aqueous suspensions, the measurement error for the mixing ratio and particle size parameters are found to be less than 7% and 10%, respectively, when compared to the image method and the given values. Nevertheless, the measurement errors are slightly increased in a non-spherical mixed particle system, where the volume median diameter and mixing ratio are still less than 10%. The MC modeling and PSO algorithm offer the potential to characterize particle size and mixing ratio for mixed particle systems in industrial applications.

关键词： Monte Carlo method mixed particle system polydispersity ultrasonic attenuation parameter inversion

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Preparation and assessment of a novel hydrated salt PCM applied for intermittent floor radiant heating systems

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JOURNAL OF ENERGY STORAGE 2025年 105卷

作者： Liu, Jie Yang, Yingying Li, Aizheng Wang, Wensong Wu, Weidong Zhang, Hua Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China

Intermittent floor radiant heating is widely employed in building heating systems. However, it suffers large indoor air temperature fluctuations due to its intermission. The integration of phase change material (PCM) can significantly mitigate this issue. In this study, Na2HPO4 & sdot;12H2O and Na2SO4 & sdot;10H2O were used as raw materials, with expanded perlite (EP) as the porous medium, to prepare a shaped composite phase change material (EPPCM). This material was then blended into mortar to produce a novel phase change mortar (EPPCM-M). Experiments were carried out to evaluate its heat storage performances. Compared to normal mortar, EPPCM-M of 25 mm thickness mitigates temperature fluctuations, with the peak temperature on the cold end reduced by about 2.5 degrees C and a slower cooling rate on the hot end. To assess the practical application of EPPCM in buildings, a simulation study was conducted. A room model of 4 x 4 x 3 m was built and subjected to radiant floor heating for 8 h daily, under the winter climate conditions of shanghai from November 15th to March 14th. The results showed that the EPPCM-M can effectively suppress temperature fluctuations in both the floor surface and average indoor air temperatures. From February 27th to March 5th, the maximum fluctuation of floor surface temperature was reduced by 55.4 %, the maximum fluctuation of average indoor air temperature was reduced by 39.5 %. The application of the EPPCM-M in intermittent floor radiant heating not only ensures indoor thermal comfort but also achieves heat's "peak load shifting", improving indoor comfort, reducing heating energy consumption, and promoting building energy efficiency.

关键词： Phase change material Thermal storage performance Intermittent floor radiant heating system Numerical simulation

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A novel hybrid approach for high-efficiency and low-load airfoil design for H-type vertical axis wind turbines

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PHYSICS OF FLUIDS 2025年第3期37卷

作者： Huang, ShengXian Ng, Eddie Yin Kwee Li, Chun Zhang, Yongxing Moghtaderi, Behdad Wang, Ying Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Nanyang Technol Univ NTU Sch Mech & Aerosp Engn Singapore 63904455 Singapore Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China China Univ Petr Natl Engn Lab Pipeline Safety MOE Key Lab Petr Engn Beijing Key Lab Urban Oil & Gas Distribut Technol Beijing 102249 Peoples R China Univ Newcastle Ctr Innovat Energy Technol Callaghan NSW 2308 Australia

The bionic approach enables the rapid excellent design, avoiding the complexity and time-consuming traditional optimization processes. To swiftly develop a high-efficiency airfoil suitable for vertical axis wind turbines (VAWTs), this study designs a novel dolphin-average airfoil (Dol-Ave airfoil) inspired by the streamlined profile of the Dall's porpoise's head. Furthermore, considering the challenges in aligning biologically inspired designs with practical engineering requirements, the Archive-based Micro Genetic Algorithm (AMGA) is adopted to refine the Dol-Ave airfoil contours by targeting high energy capture efficiency and low load. The combination of bio-inspired method and numerical optimization is referred to as the hybrid optimization method. The results of numerical simulations and comparative verification show the following: (1) When tip-speed ratio(TSR) is 0.5, compared to National Advisory Committee for Aeronautics (NACA) 0018 airfoil, the power coefficient of the Dol-Ave airfoil increases by 52.66%. However, under the high tip-speed ratio conditions, no improvement in wind energy utilization is observed. (2) The optimized airfoil (Dol-Ave opt) achieves power coefficient optimization across the full tip-speed ratio range. Compared to NACA 0018, when TSR = 0.5, the power coefficient of the Dol-Ave opt airfoil increases by 30.01%;when TSR = 1.2, the increase is 8.16%. (3) Both the Dol-Ave airfoil and the Dol-Ave opt airfoil show improvements in lateral thrust load. The bio-inspired airfoil design method and the hybrid design approach proposed in this study offer valuable insights for airfoil design.

关键词： Vertical axis wind turbine

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Study on Particle Sedimentation in a Cavity Containing Obstacles

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PROCESSES 2025年第4期13卷 980-980页

作者： Yang, Fan Shi, Ren Yan, Zhe Wang, Wencan Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China

The sedimentation of particles has a wide range of application scenarios in industry. In this paper, the sedimentation of a single particle in a cavity containing obstacles is simulated using the immersed boundary-lattice Boltzmann method. The computational results show that the presence of obstacles will alter the sedimentation of the particle, and the particle will undergo a change in the direction of rotation during the period when it tumbles over the surface of the obstacle and continues to sedimentation after leaving the obstacle. Increasing the particle-obstacle eccentricity or decreasing the particle-obstacle diameter ratio will shorten the particle-obstacle interaction time. When the sedimentation of a particle passes through the gap between two obstacles, it can be influenced by the far-side obstacle and interact with the near-side obstacle for a second time, and the influence of the far-side obstacle on the sedimentation of the particle disappears when the gap between the two obstacles exceeds a certain threshold. These results quantitatively elucidate the critical role of obstacle configuration in modulating particle dynamics, providing valuable insights for optimizing industrial sedimentation systems and advancing predictive models for multiphase flows in complex geometries.

关键词： particle sedimentation lattice Boltzmann method immersed boundary method

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Discrete element simulation of dry adhesive granular flow in a vertical pipe

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Powder Technology 2025年 460卷

作者： Gao, Xin Parteli, Eric J.R. Fan, Fengxian School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China Faculty of Physics University of Duisburg-Essen Lotharstr. 1 DuisburgD 47057 Germany Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering University of Shanghai for Science and Technology Shanghai200093 China

The transportation and storage of granular materials with adhesive properties often involves particulate flow through narrow pipes, which is accompanied by still poorly understood dynamic behavior. Due to the difficulty in achieving a quantitative understanding of such flows based solely on experiments, here we perform particle-based numerical simulations of vertical pipe flows of adhesive granular materials using the discrete element method (DEM). Our simulations unveil different regimes of vertical pipe flow depending on the pipe-to-particle diameter ratio and the interparticle adhesive strength. Surprisingly, we find that the particle mass flow rate through the pipe increases substantially with this adhesive strength. This rather counterintuitive result is caused by an enhanced tendency of the particles to form stable agglomerates around the pipe symmetry axis, thus leading to reduced interaction of the particles with the frictional pipe walls. By contrast, incorporation of particle-wall adhesive interactions leads to exactly the opposite behavior, with such interactions dictating the granular dynamics in the pipe and leading to lower mass flow rate values compared to cohesionless flows. Furthermore, we show that the different flow regimes are associated with distinct spatiotemporal patterns of the granular solid fraction along the pipe axis (density waves). Therefore, our results provide theoretical references for future experimental research and application of adhesive granular flows through narrow pipes. © 2025 Elsevier B.V.

关键词： Channel flow

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Temperature distribution measurement of solid propellant combustion based on dual-wavelength imaging method

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MEASUREMENT 2025年 247卷

作者： Yang, Bin Cao, Huayu Li, Lingfeng Fan, Rong Wang, Zhixin Yang, Yang Shi, Zhiquan Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China Shanghai Space Prop Technol Res Inst Shanghai 201109 Peoples R China

The combustion temperature is an important parameter that characterizes the combustion behavior and energy of solid propellants. It can provide data support for the research of solid propellant combustion mechanisms and the establishment of combustion models. However, the combustion of solid propellants involves hightemperature and multiphase physical and chemical processes, which pose difficulties for thermometry. Therefore, this study selected the 680 nm and 760 nm wavelengths through mathematical simulation and designed a dual wavelength radiation image measurement system for spectral splitting. The temperature distributions of HTPB propellant with different formulas were obtained using this system. The combustion temperatures of three different formulas of propellants are 2045.3K, 1915.5K, and 1855K, respectively;The uncertainties are +/- 29.8K, +/- 33.9K, and +/- 31.8K, respectively. The measurement results show that aluminum content is an important factor affecting the combustion characteristics of HTPB solid propellants. As the aluminum content increases, the combustion temperature and rate will also increase, and the flame shape will also change accordingly. It provides effective measurement methods for the analysis of combustion performance and formulation optimization of solid propellants.

关键词： Combustion diagnostics Temperature measurement method Solid propellant Dual-wavelength temperature measurement method Radiation imaging method

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The heat transfer enhancement mechanism for composite phase change material based on variable heating power and pore density

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JOURNAL OF ENERGY STORAGE 2025年 115卷

作者： Wang, Zilong Zhu, Hua Gui, Jintao Zhang, Hua Wu, Weidong Li, Ying Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China Univ Shanghai Sci & Technol Sch Mat & Chem Shanghai 200093 Peoples R China

Adding foam metal materials is one of the key methods to enhance the thermal conductivity of phase change materials (PCMs). To investigate the heat transfer mechanism of PCMs under different heat source powers and foam metal pore densities, a visualized thermal energy storage device was designed and constructed in this study. The effects of heat source power and the pore density of copper foam metal on the thermal properties of the composite PCMs, including internal temperature differences, equivalent thermal conductivity, comprehensive heat transfer coefficient, and heat storage performance during the melting process, were thoroughly analyzed. An empirical correlation for calculating the Nusselt number (Nu) of the composite PCMs was also derived. The research results indicate that the rate of temperature rise in the internal temperature difference of the composite PCMs increased with the rise in heat source power, while the melting time shortened accordingly. When the heat source power was increased from 30 W to 90 W, for composite PCMs with copper foam, the pore density of copper foam increased from 5PPI to 25PPI, and the rate of temperature rise in the internal temperature difference during the melting process enhanced from 176.9 % to 183.5 %, while the reduction in melting time enhanced from 61.9 % to 62.5 %. The comprehensive heat transfer coefficient of the composite PCMs is directly proportional to the heating power and inversely proportional to the pore density. When the heating power is increased from 30 W to 90 W, the comprehensive heat transfer coefficient of the composite PCM with a pore density of 5PPI is increased by 61 %, while that of 25PPI is increased by 59 %. Additionally, based on the structural parameters of copper foam metal, an empirical correlation for the Nu during the melting process of the composite PCM was derived, the error between the experimental value and the calculated value is +/- 5 %. In addition, the dimensionless heat-storage rat

关键词： Phase change material heating power Pore density Enhanced heat transfer Foam meta

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Pore-scale study of coupled charge, gas, and liquid water transport in the catalyst layer of PEM fuel cells

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FUEL 2025年 380卷

作者： Dou, Shaojun Hao, Liang Wang, Yuanhui Wang, Qianqian Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China Yanshan Univ Sch Vehicle & Energy Qinhuangdao 066004 Peoples R China

Understanding the catalyst layer (CL) structure-process-performance relationship is essential for optimizing proton-exchange membrane fuel cells. This study stochastically reconstructs a high-resolution porous CL with a full thickness of 8 mu m. The liquid water distribution within CL is simulated by a capillary condensation model, and a pore-scale model coupling oxygen and proton transport with electrochemical reaction is developed to investigate the CL structure-performance relationship under different operating conditions. Results indicate that CL exhibits better performance at higher humidities, up to the flooding threshold at the water saturation of 0.41, as the benefits of increased electrochemical surface area, enhanced proton conductivity, and improved oxygen permeability through the ionomer film significantly outweigh the increased transport resistances through both the pores and the water film. Under the flooding condition at water saturation of 0.41, CL performance starts to decline due to the sharply increased pore resistance. Proper perforation of CL is suggested to alleviate the pore resistance in flooded electrodes. Additionally, reducing the Pt-to-C mass ratio is found to achieve better Pt dispersion in low Pt-loaded electrodes, thereby lowering the local oxygen resistance, and the bilayer CL design with higher Pt content on the membrane side is shown to further mitigate the performance degradation.

关键词： Polymer electrolyte membrane fuel cell Liquid water Pore-scale model Catalyst layer

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