bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigation of momentum and heat transfer characteristics of Maxwell fluid cascading over a stretching sheet: A HAM approach
Authors: M N Pooja , S K Narasimhamurthy
Published: June 2024

This paper presents a novel investigation into the intricate behaviour of momentum and heat transport phenomena in a non-Newtonian Maxwell fluid flowing over a stretching sheet. Incorporating thermal radiation

R

d

,

magnetic fields

M

,

buoyancy effects

λ

T

,

and porous media

K

under convective boundary conditions the study unveils complex fluid behaviours. Energy equation has been obtained by incorporating non-uniform heat source/sink along with viscosity of the fluid as a function of temperature across the domain. Leveraging the Lie Scale transformation technique, the governing non-linear partial differential equations are converted into non-linear ordinary differential equations. With the aid of Homotopy Analysis Method (HAM), a semi-analytical technique, the solutions describing the physical phenomenon of the current model have been obtained. Further, the results are assessed through the graphical analysis of the velocity profile

f
′

η

,

thermal profile

θ

η

,

skin friction coefficient

C

f

R

e

1
2

,

and Nusselt number

N
u
R

e

−

1
2

.

The obtained results using HAM shows good agreement with the existing literature. The present work offers practical implications for various engineering applications.
A compact highly flexible two-element wideband MIMO antenna based on modal analysis for 5G wireless applications
Authors: John Deepthi Mariam , Vincent Shweta , Pathan Sameena , Ali Tanweer
Published: June 2024

The ever-evolving world of wearable technology demands compact, highly efficient, and flexible antennas to meet a seamless communication. To keep pace, a compact, flexible two element antenna with a low profile of 20 × 30 × 0.1 mm3 is presented in this article for 5G wireless applications. A lotus shaped radiator with stub integrated defective ground structure provides the desired band of interest with a measured impedance bandwidth of 4.56–5.65 GHz and isolation of 21 dB throughout the bandwidth. Characteristic mode analysis is exclusively utilized in this study to investigate and design the decoupling mechanism to improve the isolation. SAR analysis is performed using the Specific Anthropomorphic Mannequin (SAM) head model and a low SAR profile of 1.088/0.276 W/kg for 1 g/10 g is achieved. MIMO diversity performance of the antenna also shows favourable results with ECC < 0.5, DG ∼10, TARC < −10dB, MEG < −3 dB, CCL < 0.4 bps Hz−1 and ME < −0.5 that favours its applicability for real time MIMO applications.
Quantum nonlocality phenomena in scalar and Dirac fields near a Schwarzschild black hole
Authors: Sun Wen-Yang , Ma Wenchao , Wang Dong , Ye Liu
Published: June 2024

In this work, we explore the impact of the Hawking effect on quantum nonlocality, specifically the maximum violation of the Bell-CHSH inequality, for both scalar and Dirac fields within Schwarzschild spacetime. We reveal the nuanced behavior of the Bell-CHSH inequality as the Hawking temperature (HT) varies. For scalar fields, we observe distinct degradation patterns in the Bell-CHSH inequality, influenced by the state parameter α and its normalized counterpart

1
−

α
2

. In contrast, Dirac fields exhibit two distinct degradation trajectories, each converging to different nonzero minimum values as HT approaches infinity

T
→
∞

, however, this does not apply to the maximally entangled state. Remarkably, the maximum violation of Bell-CHSH inequality becomes zero for scalar fields at infinite HT, while it stabilizes at a finite nonzero value for Dirac fields. Additionally, the quantum nonlocality robustness of the Dirac fields is stronger than that of the scalar fields. Therefore, this study enhances our understanding of the dynamic characteristics of nonlocality within scalar and Dirac fields near a Schwarzschild black hole.
Day-to-day behaviour for pedestrians in a circle antipode scenario: experiment and simulation
Authors: Xiao Yao , Mai Jin , Jiang Gege
Published: June 2024

This study aims to investigate the behavioural evolution patterns of pedestrians who repeatedly traverse the same scenarios. To accomplish this objective, we implemented a repeated circle antipode experiment, ensuring consistent conditions for all participants. This experimental design allows for an effective examination of participant performance across multiple rounds. Our findings revealed that specific walking characteristics experienced significant changes with the progression of successive experiments, and participants demonstrated notable differences in their chosen routes. Recognizing the ability of the day-to-day dynamic model to describe the evolution of network flows and the similarities between traffic and pedestrian flows, we apply the modelling approach of the day-to-day dynamic model to the construction of pedestrian route choice modelling. Consequently, we developed a series of round-to-round pedestrian route choice models to characterize our experiment. These models factored in both historical walking experiences and the influence of neighbours. Our model proved to be reliable, achieving a route choice accuracy of approximately 80% in simulations of circle antipode experiments. The results of this study can provide valuable insights into pedestrian dynamics, aiding in understanding pedestrian behaviour during repetitive walking and facilitating the development of more accurate round-to-round route choice models.
Corrigendum: CNN Combined with Attention Module for Facial Expression Recognition (2023 J. Phys.: Conf. Ser. 2646 012023)
Authors: Yang Tiancheng
Published: June 2024

Please see Article PDF for corrigendum text.
Influence of trailing edge radius of intake struts on excitation force and vibration of rotor blades
Authors: Peng Wei , Li Xuesong , Ren Xiaodong , Gu Chunwei , Que Xiaobin
Published: June 2024

Adjusting the trailing edge radius of the intake struts may be advantageous in suppressing the vibration of compressor rotor blades. To explore the impact of the intake struts trailing edge radius on the excitation force and vibration, this study focuses on a compressor with intake struts, and fluid and vibration calculations were conducted. The study revealed that decreasing the trailing edge radius led to a reduction in separation near the strut’s trailing edge, resulting in a narrower wake and weakened mixing near the trailing edge. This caused the total pressure loss region induced by the wake to become more elongated in the low-frequency component, leading to a nonlinear decrease in total pressure amplitude with the reduction of the trailing edge radius. As the trailing edge radius decreased, the excitation force and vibration amplitude of the first-stage compressor rotor blades decreased, while the excitation force distribution showed little variation. The research findings provide insights for the design of intake struts.
Stability of Pt1/CeO2 single-atom catalyst in oxygen-poor environments: first-principles insights
Authors: Yan Jiasi , Xiao Wei , Zeng Rong , Li Xiaowu
Published: June 2024

Due to its exceptional oxygen storage/release capabilities, excellent catalytic activity, and selectivity, the single-atom Pt1/CeO2 catalyst has demonstrated significant research prospects and development promise in fuel cell applications. Investigating how the Pt1/CeO2 system behaves in oxygen-poor environments has become a focal point of current research. In the present work, the formation of oxygen vacancies as well as their impact on the stability of Pt adsorption in different Pt1/CeO2 systems under oxygen-poor conditions is systematically investigated. The research findings indicate that the ease of oxygen vacancy formation is primarily dictated by the structure of the Pt1/CeO2 system, with a higher propensity in low-stability systems (PtOB/CeO2, PfCeT/CeO2, PtOT/CeO2). Oxygen vacancies tend to form away from Pt positions (at the 2NN positions). Oxygen-poor and high-temperature environments promote the formation of oxygen vacancies in Pt1/CeO2 systems. Furthermore, in low-stability systems, oxygen vacancies, through adjustments to the system’s electronic structure, such as increasing the quantity of Ce3+ polarons and the transferred charge amount of Pt atoms, significantly enhance the adsorption strength of Pt atoms. This study aims to offer new insights and avenues for the design of fuel cell catalysts, promoting practical applications and development in fuel cells.
Vibration analysis of an open cylindrical thin shell under random excitation
Authors: Wang Zhaodong , Li Pu , Jiang Jian
Published: June 2024

This paper introduces an analytical approach to the random vibration of a cylindrical thin shell structure with an opening angle of 180°. The approach involves employing the exact analytical solution for the natural vibration of a thin shell structure with an opening, grounded in a continuum model, and a pseudo-excitation method to derive the exact analytical solution of the random response power spectral density for the open cylindrical thin shell structure. Simultaneously, a comparison is made between the results obtained through the analytical method and those obtained by using the finite element program, confirming the effectiveness of the analytical model constructed in this study. Finally, an analysis is conducted on the impact of thickness on the characteristics of the vibration response of the open cylindrical thin shell.
Experimental study of the restitution coefficient of spherical particles
Authors: Zou Zhixiang , Liu Yanping , Zhang Xingang , Yao Wenli
Published: June 2024

The restitution coefficient is a crucial indicator of energy dissipation. This article discusses the used restitution coefficients and presents a method to measure particle velocities before and after collisions using high-speed camera testing. The study primarily explores the influence of particle characteristics (collision velocity, collision angle, rotation speed, and collision material) on the restitution coefficient during collisions between spherical particles and a flat plate. The main focus is on studying how changes in collision angles impact the restitution coefficient. Different materials ball collision test examines the effects of steel balls, glass balls, and resin balls on the restitution coefficient. The data collected during the tests are processed by using various parameters to deduce the restitution coefficient during particle collisions. The article also analyzes the patterns of changes in the restitution coefficient for spherical particles under different collision conditions. Additionally, it derives the relationship between the restitution coefficient and different influencing factors, such as varying collision materials and initial speeds. The experimental results demonstrate a direct correlation between the restitution coefficient, the material of the particles under study, particle size, and particle spin speed.
Effect on wetting properties of the Al-Ti system by the addition of different alloying elements
Authors: Zhu Minxin , Zhang Bo , Li Zhengkun , Hao Shuai
Published: June 2024

With lightweight and high-strength, Al-Ti composites have become one of the indispensable materials in the aerospace and automotive manufacturing fields. However, due to strong interfacial reactions, the traditional pure Al-Ti composites have been limited in practical applications. To better control the interfacial reaction between the reinforced phase and the matrix in the Al-Ti composites, in this paper, the effect on wetting behavior and interfacial properties of the Al-Ti system by the addition of different alloying elements (Si, Mg, Zn, Cu) in Al melt were systematically investigated using the sessile drop method. According to the results, adding Si, Mg, Zn, and Cu elements to the Al melt can increase the steady-state wetting angle to varying degrees at the end of the holding period compared to the pure Al-Ti wetting but still maintains good wettability. The Mg, Zn, and Cu elements ensure good wettability and simultaneously reduce the temperature required for wetting, providing novel ideas for preparing aluminum matrix composites. All the systems in this experiment are typical of reactive wetting. The system with added Si and Cu showed a clear interfacial layer at the Al-Ti interface, which was comparatively smooth, and both the original Al-Ti reaction at the interface and the dissolution of the Ti substrate are inhibited.
A novel TaMoNbCrTi refractory high-entropy alloy produced by powder metallurgy
Authors: Gao Shengqing , Li Xiaoqiang , Fan Jiafeng , Qian Hao , Xu Changyu
Published: June 2024

The process of mechanical alloying (MA) and spark plasma sintering (SPS) were employed to manufacture a novel TaMoNbCrTi refractory high-entropy alloy. The investigation concentrated on how variations in sintering temperatures resulted in microstructural differences, which in turn altered the mechanical properties of TaMoNbCrTi. A BCC-structured solid solution phase was formed as a result of the MA process. During further sintering, the Cr2(Ta, Nb) phase and Ti(O, N) phase precipitated from the BCC phase. The Cr2(Ta, Nb) phase volume fraction declined and transitioned from a reticular distribution to a dispersed distribution as the sintering temperature rose. Additionally, a considerable enhancement in the Ti(O, N) phase size was observed. Because of the uniform distribution of the fine precipitated phases, the TaMoNbCrTi alloy sintered at 1200 °C demonstrated superior mechanical properties.
Influence of structure and properties for laser cladding fe based alloy on 45 steel surface
Authors: Liu Huihui , Lin Xichen , Zhang Xinjian , Yang Tiancheng , Yi Fenglin , Xu Weiye
Published: June 2024

This article uses 45 steel as the substrate and iron based alloy powder as the cladding material for mining machinery equipment. Laser cladding experiments were conducted without scanning speed to prepare 45 steel surface cladding iron based alloy layer samples. The samples were subjected to microstructure analysis, hardness, and acid corrosion resistance testing. The results show that the microstructure of the laser cladding layer is a fine-grained equiaxed crystal structure, and the hardness of the cladding layer is higher than that of the substrate. The corrosion rate of the cladding layer is low in various acid corrosive environments. The laser cladding layer is significantly higher in all aspects than the substrate, achieving the goal of high-quality preparation of iron based alloy coatings on the surface of 45 steel substrates.
Effect of grain size of nanocrystalline metals on the loss modulus
Authors: Wang Fei , Li Li , Hu Yujin
Published: June 2024

The unique distribution of grain boundaries (GBs) and grains in nanocrystalline metals makes it interesting to study the mutually exclusive properties of modulus and damping. This study carried out large-scale calculations about the grain size effects through molecular dynamics and comprehensively analyzed the static modulus and damping properties of nanocrystalline metals using the loss modulus as the merit value. The research reveals that as grain size increases, the dissipation in polycrystalline metals transitions from being dominated by GB sliding in small grains to being jointly dominated by GB sliding and intragranular dislocation in larger grain structures. This transition is similar to the one observed in plastic flow stresses in nanocrystalline materials under finite deformation, i.e., the transition from the inverse Hall-Petch mechanism to the Hall-Petch mechanism. The mechanistic conversion of these two dissipations is demonstrated by quantitative characterization. This study is instructive for the mechanical design and development of nanocrystalline metals.
Research on bird strike resistance performance of hollow plates with warren structure
Authors: Wang Bin , Lv Jinfeng , Ning Yu , Tang Zhongbin , Wang Cunxian
Published: June 2024

This study initially conducted bird strike tests and numerical simulations on hollow plates with the Warren structure. The plates manifested notable plastic deformation devoid of fracture. The simulated deformations and strain data of the plates closely corresponded with the outcomes of bird strike impact tests, thereby validating the employed bird strike simulation methodology in this study. Subsequently, while maintaining the outer dimensions of the hollow plate constant, an investigation into the structural parameters of the hollow plate was conducted. Correlations between the thickness of the outer panel, thickness of the Warren, angle of the Warren, and the anti-bird-strike performance of the hollow plate structure were established. The research findings offer valuable insights for informing the design of bird strike resistance in engine blades and hollow plates.
Research on corrosion resistant of shot peening to micro-arc oxidation coating on ZL101A
Authors: Zhu Yaokai , Zhou Mengyue , Da Qiupan
Published: June 2024

The corrosion of ZL101A in a 3.5% NaCl solution was studied using the polarization curve method. The effect of the composite treatment of shot peening and micro-arc oxidation on the corrosion resistance was investigated compared with the single treatment of micro-arc oxidation. The results showed that compared with the single treatment of micro-arc oxidation, the composite treatment can significantly reduce the depth of intergranular corrosion and self-corrosion current density of ZL101A, exhibiting minimal effect on the self-corrosion potential. The shot peening treatment was beneficial in reducing the corrosion sensitivity of ZL101A.
Testing and finite element analysis of internal mechanical properties of compressed concrete
Authors: Zhang Yaoyuan , Li Jinhu , He Haoxiang
Published: June 2024

In order to conduct intensive research on the inside stress-strain curve relationship of compressed concrete, a novel relevant testing device was developed and embedded inside concrete specimens and we conducted conventional uniaxial compression loading tests on concrete specimens. Based on experimental data, combined with several typical constitutive equations of concrete, simulation is conducted on the experiment. The results show that the core area inside the concrete has good ductility compared to the other parts, and the measured constitutive curve inside the concrete is reasonable and accurate, which is in good agreement with the finite element simulation results based on Chinese standards. It proves that the relevant measurement methods have fine accuracy and applicability, and can be further promoted and used.
In-plane shear failure behavior and mechanical properties of SiC/SiC Composites
Authors: Li Tianshan , Yu Guoqiang , Zhou Shihao , Zheng Zhikang , Gao Xiguang , Song Yingdong
Published: June 2024

Fiber-reinforced ceramic matrix composites, especially SiC/SiC composites, have the characteristics of lightweight, high strength, high-temperature resistance, etc., which are ideal structural candidates for aerospace vehicle components, in-plane shear performance is one of the important indicators to characterize the mechanical properties of materials and component assessment, this paper designs and processes the in-plane shear test pieces and test devices and methods to study the shear mechanical behavior under the mechanical properties and failure behavior of SiC/SiC ceramic-based fiber bundle composites are studied under shear mechanical behavior. The results show that matrix cracking and fiber fracture are the main failure modes, and there are two obvious phases in the specimen shear force-displacement curves, and fiber fracture is the main cause of strain in the specimen.
Simulation of melt kinetics of in-situ molding of thermoplastic CF/PEEK composites
Authors: Jin Caizhi , Wang Fei , Zhang Chengshuang , Bao Yanling , Zhang Chenghao , Wang Mengjie , Liu Dong , Wu Jing , Su Zhongmin
Published: June 2024

To reveal the interaction mechanism between the composites and the laser during the laser in-situ forming process of carbon fiber composites, the temperature change history and phase transition process on the surface of CF/PEEK composites under the action of flat-top beams with different moving directions were simulated by using COMSOL Multiphysics finite element simulation software. The results show that, due to the anisotropy of CF/PEEK composites, the transverse spread of the temperature field is always larger than the longitudinal spread, and when the moving angle is less than 45°, the surface temperature and the surface heat-affected zone of CF/PEEK composites increase with the increasing of the moving angle. The surface temperature and the area of heat affected zone are maximum when the angle of movement is 45°. As the angle of movement increases from 45° to 90°, the area and temperature of the heat-affected zone on the surface of the composite decreases with the increase in the angle of movement. The area of the melting zone is consistent with the distribution of the temperature field on the composite surface. The transverse broadening of the melting zone is always larger than the longitudinal broadening. The area of the melting zone is largest when the laser spot moves at an angle of 45°, and the area of the melting zone is smallest when the spot moves at an angle of 90°.
Study on the flow characteristics of gas-solid two-phase flow in a horizontal-vertical pneumatic conveying system based on dunes
Authors: Wang Yunfei , Yan Fei
Published: June 2024

In this paper, based on the accumulation pattern of particles flowing through the bend, the Dunes are designed to be placed in curves with different radii of curvature in a horizontal-vertical pneumatic conveying system, and the movement characteristics of the particles entering the vertical pipeline due to with Dunes are analyzed based on CFD-DEM. Compared to the case of No Dune, the Gas-solid two-phase velocities with Dune are almost evenly distributed in the pipe and are larger than the corresponding case of No Dune. At the same time, the particle axial velocities with Dunes are larger than the case without Dunes, the number of collisions of particles in vertical tubes is reduced due to Dunes, and the particles diverge sufficiently throughout the vertical tube from the particle flow patterns. The results show the effect of Dunes can increase the velocity of particles and reduce the impact of particles on the pipe wall, it is conducive to the transport of particles. Meanwhile, The experiment known as particle image velocimetry (PIV) verifies the accuracy of the numerical simulation results.
Soft rock rheological similarity criterion under thermal-mechanical effects—a research and its application
Authors: Fan Xiyan , Han Xianglian , Hua Zezhen , Yin Xiaoxia , Li Qian , Tan Yuan
Published: June 2024

The similarity criterion of soft rock in both the linear elastic deformation range and the rheological process are systematically studied in this paper by using the equation derivation method and the dimensional analysis method under the effects of temperature and pressure. A brief analysis is performed and COMSOL is used to verify the deduced similarity criterion numerically. A shale-like material with paraffin wax as the binder and river sand as the main aggregate is then prepared by following the similarity criterion, including compressive strength, tensile strength, elastic modulus, Poisson’s ratio, and thermal conductivity. The mechanical parameters and thermal conductivity of the fabricated shale-like material are measured, and the result shows that the shale-like material has a high similarity with the shale prototype material by comparing the experimental data with the calculated data based on the similarity criterion. This reveals the significance of the similarity criterion for developing model experiments. Thus, this research has enriched the rheological similarity principle system of soft rock and has an important practical value in deep soft rock excavation and support engineering.
Study of mechanical properties of the YL113 die casting surface and middle layer
Authors: Chen Wei
Published: June 2024

The YL113 die casting surface and middle layer are separated by machining and densities, porosities and mechanical properties of the YL113 die casting surface and middle layer are measured. Results show that the densities and mechanical properties of the total YL113 die casts are in between those of the YL113 die casting surface and middle layer and are identical to those of the YL113 die casting middle layer. The porosities of the die casting surface layer are smaller and fewer and its densities are bigger and mechanical properties are better than those of the middle layer. Effects of different die casting process parameters on the surface layer and the middle layer of die casting are different, of whom effects of the casting pressure and the biscuit thickness on them are most obvious. The densities and mechanical properties of the surface layers and the middle layers of die castings increase with increasing the casting pressures and the biscuit thicknesses. In addition, the effects of densities on the mechanical properties of the die casting middle layers are more obvious than those of the die casting surface layer.
Study on physiological injuries of occupants under vertical impact loads
Authors: Qin Weiwei , Wang Xianhui , Sun Xiaowang , He Jiahao , Yao Tuzao , Li Mingxing , Wu Mengyang , Fu Tiaoqi
Published: June 2024

Under vertical impact loads, such as explosions, serious compressive deformation occurs in the pelvic bones and lumbar vertebrae of the human body leading to injuries or fatalities for occupants. This study focuses on the occupant-seat model in military vehicles, establishes a biomechanical model of the human spine, and establishes the relationship between vertical impact loads and human injuries. Subsequently, a C-shaped energy-absorbing cushioning structure is designed for application at the bottom support of the seat. Using a peak value of 50 g explosion-simulated triangular wave loading, the study compares the attenuation effects of different structural characteristics of cushioning energy-absorbing structures on impact loads. The results indicate that a 50 g peak vertical impact load can cause significant human injuries. The designed energy-absorbing cushioning structure can greatly reduce human response, but both excessively soft and rigid energy-absorbing cushioning structures fail to achieve effective impact attenuation.
Manufacturing techniques for composite structure batteries: laminates and sandwich panels
Authors: Wang Xiaochen , Liu Xiaoyu , Mao Rui , Lei Zhenkun , Bai Ruixiang
Published: June 2024

The laminated and sandwich composite structural batteries can efficiently store energy and bear loading while effectively saving mass and volume. To prepare these two types of composite structure batteries, an experimental platform of vacuum-assisted resin transfer process was constructed, and the preparation processes of laminated and sandwich plates were studied. The comparative analysis of the open-circuit voltage with SOC at different temperatures demonstrated the stability and reliability of the preparation processes for composite structure batteries.
Strength analysis for civil aircraft fuel tank inerting system based on caepipe finite element modeling
Authors: Yue Peng , Zeng Zhe , Gao Chenhu
Published: June 2024

This paper examines the architecture and component characteristics of the fuel tank inerting system in civil aircraft, as well as the loads it experiences. The study further investigates the strength of the system through a finite element model analysis by using CAEPIPE and explores the design of the bracket supporting the inerting system. The paper aims to contribute to the field by providing a detailed analysis of the fuel tank inerting system and its components, as well as offering insights into the system’s strength and design considerations.
The numerical simulation investigates the influence of agitator parameters on particle suspension characteristics
Authors: Zhao Xiuzheng , Qu Chang , Jin Zheng , Zhao Kai
Published: June 2024

This study investigates the effect of different agitator parameters in a baffleless stirred reactor on solid particle suspension during quaternary ammonium chitosan synthesis. Computational Fluid Dynamics (CFD) simulations investigate different agitator configurations, including blade diameter, rotational speed, and bottom clearance, to optimize chitosan particle distribution. Reducing the bottom clearance reduces particle accumulation, but can create stagnant zones that may disrupt fluid flow. Increasing the rotational speed improves particle distribution until a saturation point is reached. Increasing paddle diameter improves axial fluid circulation. Optimal settings for the vane size of a 180 mm reactor vessel are identified as 0.45 times the diameter, with a speed of 350 rpm, and a bottom clearance of 0.25 times the diameter. These simulations provide critical insight into the suspension of solid particles in baffleless stirred reactors and provide valuable guidance for optimizing stirrer parameters.
Research on the heat treatment process of intravascular nitinol stents
Authors: Zhu Lin , Teng Ruijing , Zhao Jonathon , Tu Jiangping
Published: June 2024

With the aging of China’s population and changes in dietary structure, the incidence of peripheral arterial disease (PAD) is increasing year by year, and the number of PADs requiring intervention is increasing. Atherosclerosis, inflammation, trauma or injury, structural abnormalities of ligaments or muscles, or exposure to radiation are common causes of PAD. Minimally invasive treatment is an effective method to treat PAD, and nitinol alloy vascular stent has become an effective and safe minimally invasive interventional treatment method because of its shape memory effect, super elasticity, and excellent biocompatibility. This topic mainly studies the preparation of nitinol stents through finite element analysis simulation and heat treatment shaping. The stents are analyzed by optical microscope, DSC, Tensile Testing Machine, and Radial Force Tester. The specific research results are as follows: through finite element analysis, the shaping process parameters of the stent are determined. When the diameter of the stent is expanded to 5 mm in three steps, as the heating temperature increases from 500°C to 540°C, the color of the stent surface changes from blue to yellow, the temperature of the stent Af decreases, the radial support force and the stress of the upper and lower yield plateaus of the stent increase.
Experiments for control of boundary layer transition by plasma actuators
Authors: Song Tianwei , Zhang Ziqi , Shi Zhenxing , Chi Dejian , Duan Xu
Published: June 2024

Plasma flow control technology is a new type of active flow control technology, and this paper carries out certain research on the basic principle of plasma flow control technology and its application on the wing model. The paper introduces the theory of plasma discharge and analyzes how plasma can control the flow field. A parallel dielectric barrier discharge plasma exciter is then designed and tested by using the Particle Image Velocimetry (PIV) technique to investigate the spatial flow field distributions of single-stage and three-stage actuators, and the mechanism of jet generation by the actuator is analyzed. Finally, the plasma actuator was utilized to control flow separation on a super-zero-boundary airfoil, and the oil droplet interferometric method was used to study the actuator’s role in controlling boundary layer transition. The experiment revealed that increasing the actuator discharge voltage can further reduce wall drag and more effectively delay the transition. Under the given conditions of a head-on angle of 6° and the incoming wind speed of 20 m/s, a two-stage actuator’s continuous discharge parameter was set to an output voltage of 12 kV and an output frequency of 4.7 kHz. The results showed that the transition position can be delayed by 13%, indicating the effectiveness of the actuator’s jet effect in enhancing the stability of the boundary layer flow.
Effect of the span length for using finite to analogize infinite beam on viscoelastic foundation under a harmonic moving load
Authors: Gao Siyu , Shi Kang
Published: June 2024

Railways with continuous rails are often modeled as infinite beams. In this paper, closed-form solution is firstly derived for the response of an infinite beam supported by viscoelastic foundation under a harmonic moving load by residue theorem method. The most suitable span length will be found for the analogic finite beam to best represent the deflection of the infinite beam for practical reasons. Starting from the equations of motion, closed-form solution is firstly derived for the infinite beam. Then, a FEM modeling procedure will be adopted to conform the validity of the solution derived analytically. The deflection curves of the infinite beam and analogic finite beam are compared for various parameters.
Analysis of failure mechanism of local compression in concrete cone foundation based on FEA
Authors: Liu Hong , Xiao Meiling , Xie Jin
Published: June 2024

The ANSYS software is used for finite element numerical simulation to analyze the failure mechanism of local compression in concrete cone foundations in conjunction with previous experimental experience. The results reveal that the “hooping action” of surrounding concrete and the arch structure under the compression zone causes the increase of local compression in the concrete cone foundation. According to the findings of the analyses, the failure of local compression in concrete cone foundations is caused by the combined action of top shear force, middle splitting force, and top splitting force. The results also demonstrate that the failure mechanism of local compression in concrete cone foundations may be explained more rationally by integrating the theories of hoop strengthening and shear strength. These results serve as a basis for further study into the calculation method of cone foundation local compression.
Influence patterns of shear-thickening gel on overload transmission: a numerical simulation study
Authors: Wang Shuai , Pi Aiguo , Wang Shaohong , Huang He
Published: June 2024

To address signal aliasing challenges encountered by smart munition fuzes during penetration and layer counting processes, this study employs shear-thickening gel (STG) as a cushioning protective material for accelerometers. Based on the SHPB test platform, the test is designed and the finite element numerical simulation is carried out. The thickness of the shear-thickening gel specimen is treated as a research variable, enabling a systematic analysis of its mechanical filtering effect on overload acceleration. Furthermore, a spring-damping physical model for the cushioning structure is established, facilitating a theoretical exploration of the filtering mechanism on the acceleration signal. Research findings indicate that within a certain frequency bandwidth, STG materials can effectively filter out high-frequency signals received by the accelerometer. Additionally, augmenting the thickness of STG materials has a positive impact on achieving superior filtering performance within the high-frequency range.
A generalized wind turbine cross section as a reduced-order model to gain insights in blade aeroelastic challenges
Authors: Branlard E. , Jonkman J. , Porter J. H. , Vijayakumar G. , Jonkman B. , Singh M. , Mayda E. , Dixon K.
Published: June 2024

In this work, we present an approach to study the aeroelastic stability of a wind turbine by focusing on the dynamics of a blade cross section. We present a methodology to obtain a reduced-order model of the blade dynamics in the form of generalized cross-sectional quantities that approximates the aerodynamic and structural properties of the full blade. The motivation for the work is to gain a physical understanding of the influence of aerodynamic models such as dynamic wake and dynamic stall on the frequency and damping of the structure using a reduced-order model with low computational cost. The model may be coupled to two-dimensional computational fluid dynamics softwares or engineering unsteady airfoil aerodynamics models accounting for dynamic wake and dynamic stall. In the latter case, we can obtain monolithic state-space forms of the aeroelastic system of equations, which simplifies the determination of the modal parameters and therefore the study of stability. The work investigates wind turbines in operation or at standstill, where vortex-induced vibrations and stall-induced vibrations, respectively, might be an issue. The implementation is made available as part of the open-source Python package WELIB and as part of the open-source unsteady aerodynamic driver of OpenFAST.
Challenges in Rotor Aerodynamic Modeling for Non-Uniform Inflow Conditions
Authors: Boorsma K , Schepers J G , Pirrung G R , Madsen H A , Sørensen N N , Grinderslev C , Bangga G , Imiela M , Croce A , Cacciola S , Blondel F , Branlard E , Jonkman J
Published: June 2024

Within an international collaboration framework, the accuracy of rotor aerodynamic models used for design load calculations of wind turbines is being assessed. Where the use of high-fidelity computation fluid dynamics (CFD) and mid-fidelity free-vortex wake (FVW) models has become commonplace within the wind energy community, these still fail to meet the requirements in terms of execution time and computational cost needed for design load calculations. The fast but engineering fidelity blade-element/momentum (BEM) method can therefore still be considered the industry workhorse for design load simulations.

At the same time, upscaling of wind turbine rotors makes inflow non-uniformities (e.g. shear, veer, turbulence) more important. The objective of this work is to assess model accuracy in non-uniform inflow conditions, which violate several BEM assumptions. Thereto a comparison in turbulent inflow has been executed including a wide variety of codes, focusing on the DanAero field measurements, where a 2.3-MW turbine was equipped with, among other sensors, a pressure measurement apparatus. The results indicate that, although average load patterns are in good agreement, this does not hold for the unsteady loads that drive fatigue damage and aero-elastic stability. A simplified comparison round in vertical shear was initiated to investigate the observed differences in a more controlled manner. A consistent offset in load amplitude was observed between CFD and free-vortex codes on the one hand and BEM-type codes on the other hand. To shed more light on the observations, dedicated efforts are ongoing to pinpoint the cause for these differences, in the end leading to guidelines for an improved BEM implementation.
Impacts of dynamic stall on engineering model predictions of wind turbines loads under design load cases
Authors: Bangga Galih , Yu Jingyi
Published: June 2024

The present work is aimed specifically at providing an order of estimate of the load changes due to the inclusion of unsteady aerodynamic effects. Two dynamic stall models are assessed: (1) the incompressible version of the Beddoes-Leishman model and (2) the newly developed IAG dynamic stall model. Two sets of attached flow constants are considered, based on the flat plate approximations according to Jones and the original constants adopted by the IAG model. On top of that, the influence of the impulsive contributions is also highlighted. This work is aimed at filling the gap of the state-of-the-art since at present there is no available study which compares the impacts of using the IAG model against the BL model in real design load case (DLC) scenarios required for wind turbine designs, considering it is very important to estimate loads changes depending on the engineering model being used. It will significantly influence the design of wind turbine structures, especially blades and the strength of the materials for the manufacturing process. Toward the end, providing a proper estimate into the load changes will greatly influence the cost required in blade design and manufacturing. The present study investigates the influence of dynamic stall modeling on the loads acting on wind turbines with various sizes, ranging from 2.5 MW to 8 MW of the rated power. In the studies, both onshore and offshore conditions are considered to obtain the full picture into the engineering modeling effects.
Wind Turbine Aeroelastic Stability in OpenFAST
Authors: Bortolotti Pietro , Chetan Mayank , Branlard Emmanuel , Jonkman Jason , Platt Andy , Slaughter Derek , Rinker Jennifer
Published: June 2024

Wind turbines are growing in size and increasingly suffer from aeroelastic instabilities. Unfortunately, numerical models often show inconsistent results during verification studies. We address this gap by first introducing novel linearization capabilities within the open-source aero-hydro-servo-elastic framework OpenFAST. Next, a code-to-code benchmark study is presented that compares modal parameters between OpenFAST and HAWCStab2 for a land-based version of the International Energy Agency 15-MW reference wind turbine modeled with quasi-steady aerodynamics. The two solvers are in strong agreement except for discrepancies in the second rotor flapwise modes. The differences are attributed to the torsional flexibility of the tower, which is assumed torsionally stiff in the OpenFAST model. Work is ongoing to close this modeling gap. The aeroelastic stability of a low-specific-power land-based wind turbine is also investigated. The impact of design choices is discussed, high-lighting how narrow the margins are between a stable design and an unstable design.
Assessing the impact of vortex generators on the dynamic stall behaviour of a thick airfoil
Authors: Sahoo Abhratej , Ferreira Carlos Simao , Yu Wei
Published: June 2024

Modern slender wind turbine blades use thick inboard airfoils and thicker trailing edges prone to flow separation. The increasing size of these flexible blades amplifies the importance of considering unsteady aerodynamics during the design phase. Environmental conditions result in Leading Edge Erosion (LER), further complicating the sectional unsteady aerodynamic behaviour. Although vortex generators are a well-studied method for passive separation control under steady conditions, their influence on unsteady aerodynamics for clean and rough blade sections is an area that requires further exploration. While some numerical studies exist, reliable experimental data is lacking in the literature. This work presents experimental results on the dynamic stall behaviour of a DU97W300 airfoil, a typical thick root section. The investigation covers both clean and rough conditions, both with and without VGs, to create an understanding of how VGs impact dynamic stall. Moreover, various VG array configurations are used to study the parametric dependence of dynamic stall phenomena on the VG array parameters.
Experimental and numerical comparison of aerodynamics for a wind turbine rotor model under turbulent inflow conditions
Authors: Dumanoir M , Leroy A , Guilmineau E , Loyer S , Kourta A
Published: June 2024

Computational prediction of aerodynamics for a two-bladed wind turbine rotor model at the profile, blade, and rotor scale are compared to wind tunnel experimental data. Wind tunnel tests are carried out in the large subsonic wind tunnel at the University of Orleans with an instrumented rotor model to obtain power and thrust coefficients, bending moments and pressure chordwise distributions. A passive uniform turbulence grid is used to obtain a turbulence intensity of 3.8% at the front of the rotor. A k − ω SST unsteady Reynolds-averaged Navier-Stockes (URANS) simulation with the ISIS-CFD flow solver is conducted with a fully resolved rotor, with and without automatic grid refinement. The focus of this study is to examine the prediction capabilities of the simulation for various physical variables. The simulation demonstrates a relatively good prediction of power and thrust coefficients compared with experimental data with a maximum scatter of 8.5%. The prediction of the pressure coefficient distribution at three different radial positions is satisfactory, but shows discrepancies when it comes to accurately predicting flow separation and Reynolds effects.
An aerodynamic digital twin of real-world leading edge erosion: Acquisition, Generation and 3D CFD
Authors: Meyer Forsting A , Olsen AS , Sørensen NN , Fischer A , Markussen CM , Bak C
Published: June 2024

Wind turbine blades face extremely challenging environmental conditions over their operating life-time, that can easily exceed 2 decades. Airborne particles (insects, sand, rain, hail, ice, sea spray etc.) strike the blade leading edge (LE) first and erode or attach to it, roughening its surface. Leading edge roughness (LER) can critically alter the aerodynamic performance of blades, as its aerodynamic impact is strongly coupled to its height with respect to the local boundary layer thickness, which is thinnest around the LE. The actual, detailed topographic manifestation of LER on in-service blades—needed to accurately assess its aerodynamic impact—is highly probabilistic, as it depends on the interaction of multiple stochastic parameters, like the environmental conditions, material composition and production process. Yet little high-resolution topographic LER data of this kind is currently available. This paper details how such data is collected from blades of different turbine manufacturers and processed consistently to build digital twins of the measured LER, that can be analysed aerodynamically using 3D CFD or wind tunnels. Here a special focus lies on how to reconstruct the LER topography and build the computational mesh such that the correct aerodynamic response is observed. For this purpose multiresolution signal decomposition is used to process the topographies and a special meshing procedure established.
Automatic detection and correction of aerodynamic imbalances: a noise-based approach
Authors: Sucameli C R , Bertelè M , Bottasso C L
Published: June 2024

This paper proposes the use of noise emissions to identify and rectify aerodynamic imbalances. The approach leverages the fact that a pitch imbalance changes the angle of attack at the blade sections, which in turn results in a change in noise emissions. Simulations performed on a 3.35 MW wind turbine show that aerodynamic imbalances significantly affect the Overall Sound Pressure Level at the 1P rotor frequency, more so than mass imbalances, and this effect is furthermore dependent on the microphone placement around the turbine.

The rebalancing algorithm is tested through simulations in various scenarios, including both single and multiple concurrent blade imbalances, under different wind speeds and turbulence conditions. The algorithm successfully minimizes aerodynamic imbalances in most cases.
Aerodynamic conditions measured at a rotor blade of large wind turbine prototype
Authors: Wegner Anna , Mechler Sebastian , Höning Leo , Denecke Nora , Stoevesandt Bernhard
Published: June 2024

In this paper we present high resolution pressure distributions measured on the surface of a rotor blade of an 8 MW offshore prototype. We investigate two time intervals of approximately 10 minute duration acquired in April 2022. During the first time interval the turbine is operated at rated power, during the second time interval the turbine is operated below rated power. We see a clear increase and decrease of pressure values on the pressure side and suction side of the rotor blade, respectively. Also, 1P frequency oscillations are found in all sensors except during idling state. We find a decreasing signal to noise ratio in these oscillations with increasing distance from leading edge towards trailing edge, indicating higher turbulence in the air flow. Additionally, pressure changes during pitching movements can be observed. These data present the first data set of pressure distribution measured over a longer time period on a state-of-the-art sized offshore wind turbine prototype and therefore, provide important input for model validation and further understanding of the aerodynamic conditions at a rotor blade.