Current Issue : January-March Volume : 2025 Issue Number : 1 Articles : 5 Articles
Examining dual vertical-axis wind turbines (VAWTs) across various turbulence scenarios is crucial for advancing the efficiency of urban energy generation and promoting sustainable development. This study introduces a novel approach by employing two-dimensional numerical analysis through computational fluid dynamics (CFD) software to investigate the performance of VAWTs under varying turbulence intensity conditions, a topic that has been relatively unexplored in existing research. The analysis focuses on the self-starting capabilities and the effective utilization of wind energy, which are key factors in urban wind turbine deployment. The results reveal that while the impact of increased turbulence intensity on the self-starting performance of VAWTs is modest, there is a significant improvement in wind energy utilization within a specific turbulence range, leading to an average power increase of 1.41%. This phenomenon is attributed to the more complex flow field induced by heightened turbulence intensity, which delays the onset of dynamic stall through non-uniform aerodynamic excitation of the blade boundary layer. Additionally, the inherent interaction among VAWTs contributes to enhanced turbine output power. However, this study also highlights the trade-off between increased power and the potential for significant fatigue issues in the turbine rotor. These findings provide new insights into the optimal deployment of VAWTs in urban environments, offering practical recommendations for maximizing energy efficiency while mitigating fatigue-related risks....
The numerical simulation of wear of railway wheel profiles can be a game changer in the railway field, as it can drive the planning of wheel re-turning operations, thrust the identification of optimized profiles and evaluate the safety of railway vehicles at the early stages of design. Today, commercial multibody codes are provided with dedicated routines that can evaluate the worn profile shape due to the dynamic behaviour of the vehicle. As the outputs of such modules can depend on different user-selectable parameters and modelling choices, it is vital to assess the capabilities of these codes and get a further understanding of the implemented algorithms. This paper aims to benchmark the effects of different modelling parameters and choices, mainly related to the selected wear law and wheel–rail contact method, on the final wear outputs, with special reference to the wear module provided by the SIMPACK commercial multibody code. A relevant novelty of the paper deals with the benchmarking of the wear algorithm available in the commercial code with in-house wear routines, comparing different strategies and choices for the calculation of wear. This allows us to better understand the most critical differences and modelling issues, as well as to highlight possible improvements in wear algorithms that can lead to enhanced numerical stability. More in detail, this work suggests a change in the wear algorithm that proves to be beneficial to removing local wear peaks produced by numerical sources, which could cause instabilities in the computation....
With the increasing depletion of shallow resources, mining has gradually shifted to deeper levels, and the high-temperature problem of deep mining has restricted the efficient and safe development of mining. In this study, five types of thermal insulation materials for surrounding rocks with different ratios were produced using tailings, P.O.32.5 clinker, aluminum powder, glass beads, quick lime, and slaked lime as test materials. Based on the uniaxial compression test, the thermal constant analysis test, and numerical simulation analysis technology, the change rule of mortar compressive strength and thermal conductivity was analyzed, and the cooling effect of surroundingrock thermal insulation materials with different ratios was discussed. The results showed that the compressive strength of the surrounding-rock thermal insulation materials ranged from 0.39 to 0.53 MPa, and the thermal conductivity ranged from 0.261 to 0.387 W/(K·m), with the compressive strength of ratio E being the largest and the thermal conductivity of ratio A being the lowest. In the numerical simulation analysis results, the thermal insulation layer thickness was taken as a value of 10 cm when, at this time, the best thermal insulation effect and economic benefits involved a temperature reduction of 0.9 K. In the case of changing the thermal conductivity and inlet wind speed, the original temperature of the rock temperature reduction was also very clear, with maximum reductions of 0.92 K, 0.92 K, and 1.42 K....
Two-dimensional (2D) materials have drawn extensive attention due to their exceptional characteristics and potential uses in electronics and energy storage. This investigation employs simulations using molecular dynamics to examine the mechanical and thermal transport attributes of the 2D silicene–germanene (Si-Ge) lateral heterostructure. The pre-existing cracks of the Si-Ge lateral heterostructure are addressed with external strain. Then, the effect of vacancy defects and temperature on the mechanical attributes is also investigated. By manipulating temperature and incorporating vacancy defects and pre-fabricated cracks, the mechanical behaviors of the Si-Ge heterostructure can be significantly modulated. In order to investigate the heat transport performance of the Si-Ge lateral heterostructure, a non-equilibrium molecular dynamics approach is employed. The efficient phonon average free path is obtained as 136.09 nm and 194.34 nm, respectively, in the Si-Ge heterostructure with a zigzag and armchair interface. Our results present the design and application of thermal management devices based on the Si-Ge lateral heterostructure....
Advanced manufacturing technologies have imposed higher demands on the strength, hardness, and high-temperature stability of materials, such as cuing tools, molds, and wear-resistant parts. Metal matrix composites with excellent comprehensive properties are expected to meet these demands. High-entropy alloys (HEAs), composed of unique multi-principle elements, oer high strength, hardness, and excellent high-temperature stability, superior to traditional cemented carbides in some cases. Here, the AlCoCrFeNi2.1 HEA reinforced by TiB2 was fabricated by an innovative alliance of mechanical alloying (MA) and spark plasma sintering (SPS). It was found that tuning the milling time and content of the reinforced phase could eectively realize the uniform distribution of the TiB2 reinforcement phase in the matrix. The AlCoCrFeNi2.1 with 5 vol.%TiB2 after MA for 2 h resulted in the particle renement of TiB2 and the uniform distribution of TiB2 in the matrix. And the bulk sintered at 1150 °C exhibited an excellent combination of a compressive yield strength of 1510 MPa, a compressive strength of 2500 MPa, and a high hardness of 780 HV. The analysis of dierent strengthening mechanisms suggests that the ne grain strengthening and precipitation strengthening make the HEA composite possess excellent compressive yield strength and fracture strength....
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