Article
Thermodynamics
Emad Hasani Malekshah, Wlodzimierz Wlodzimierz, Miros law Majkut
Summary: Cavitation has significant practical importance and can be controlled by air injection. This study investigates the natural to ventilated cavitation process around a hydrofoil through numerical and experimental methods. The results show that the location and rate of air injection have a meaningful impact on the characteristics of cavitation.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Mahsa Taghavi, Swapnil Sharma, Vemuri Balakotaiah
Summary: This study investigates the natural convection effects in the insulation layers of spherical storage tanks and their impact on the tanks' performance. The permeability and Rayleigh number of the insulation material are considered as key factors. The results show that as the Rayleigh number increases, new convective cells emerge and cause the cold boundary to approach the external hot boundary. In the case of large temperature differences, multiple solutions may coexist.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Mechanics
Ussama Ali, Anas Ghannam, Md Islam, Isam Janajreh
Summary: This study utilizes a passive flow control technique involving a slit through a circular structure to dampen flow-induced vibration. The results demonstrate that the presence of a slit can decrease lift and drag coefficients and suppress flow-induced vibration.
EUROPEAN JOURNAL OF MECHANICS B-FLUIDS
(2024)
Article
Mechanics
Sebastian A. Altmeyer
Summary: This article investigates how an alternating magnetic field can restrict and suppress the generation of vortices in ferrofluidic Couette flow. It finds that when the initially rotating outer cylinder is suddenly stopped, more complex vortex dynamics are generated in the system, and the presence of an alternating magnetic field can modify these dynamics, mainly depending on the modulation amplitude of the field.
EUROPEAN JOURNAL OF MECHANICS B-FLUIDS
(2024)
Article
Mathematics, Applied
S. Kumar, H. Roy, A. Mitra, K. Ganguly
Summary: This study investigates the nonlinear dynamic behavior of bidirectional functionally graded plates (BFG) and unidirectional functionally graded plates (UFG). Two different methods, namely the whole domain method and the finite element method, are used to formulate the dynamic problem. The results show that all three plates exhibit hardening type nonlinearity, with the effect of material gradation parameters being more pronounced in simply supported plates.
COMMUNICATIONS IN NONLINEAR SCIENCE AND NUMERICAL SIMULATION
(2024)
Article
Thermodynamics
Jinqi Hu, Tongtong Geng, Kun Wang, Yuanhong Fan, Chunhua Min, Hsien Chin Su
Summary: This study experimentally examined the heat dissipation of vibrating fans and demonstrated its inherent mechanism through numerical simulation. The results showed that the flow fields induced by the vibrating blades exhibited pulsating features and formed large-scale and small-scale vortical structures, significantly improving heat dissipation. The study also identified the impacts of different blade structures and developed a trapezoidal-folding blade, which effectively reduced the maximum temperature of the heat source and alleviated high-temperature failure crisis.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Qilong Liu, Dongbo Shi, Di Zhang, Yonghui Xie
Summary: This study aims to reduce pressure loss and improve flow uniformity by inserting connecting bridges of varying sizes in the mid-chord region of gas turbine blades. The suitability and performance of different connecting bridge combinations are evaluated through simulations. The results show that the incorporation of connecting bridges leads to a significant reduction in flow resistance and an increase in thermal performance.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Jiao Chen, Guofu Chen, Zhaoliang Wang, Dawei Tang
Summary: This study investigates the phonon transport processes at heterointerfaces and reveals their dependence on Al atom concentration and compressive strain. The research shows that the introduction of Al atoms and compressive strain enhance phonon-interface scattering and promote phonon transport at the heterointerface.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Mathematics, Applied
Chanh Dinh Vuong, Xiaofei Hu, Tinh Quoc Bui
Summary: In this paper, we present a dynamic description of the smoothing gradient-enhanced damage model for the simulation of quasi-brittle failure localization under time-dependent loading conditions. We introduce two efficient rate-dependent damage laws and various equivalent strain formulations to analyze the complicated stress states and inertia effects of the dynamic regime, enhancing the capability of the adopted approach in modeling dynamic fracture and branching.
FINITE ELEMENTS IN ANALYSIS AND DESIGN
(2024)
Article
Thermodynamics
Tan Lo Wong, Ke Ma, Chamil Abeykoon
Summary: This study explored the thermal properties of polyethylene glycol (PEG)-based composites by incorporating different types of carbon-based fillers. The addition of milled carbon fibre greatly improved the thermal conductivity, while graphite filler showed excellent performance in thermal diffusivity and cyclability.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Hui He, Ning Lyu, Caihua Liang, Feng Wang, Xiaosong Zhang
Summary: This study investigates the condensation, frosting, and defrosting processes on superhydrophobic surfaces with millimeter-scale structures. The results reveal that the structures can influence the growth and removal of frost crystals, with the bottom grooves creating a frost-free zone and conical edges promoting higher frost crystal heights. Two effective methods for defrosting are observed: hand-lifting the groove and airfoil retraction contraction on protruding structures. This research provides valuable insights into frost formation and defrosting on millimeter-structured superhydrophobic surfaces, with potential applications in anti-frost engineering.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Thiwanka Arepolage, Christophe Verdy, Thibaut Sylvestre, Aymeric Leray, Sebastien Euphrasie
Summary: This study developed two thermal concentrators, one with a 2D design of uniform thickness and another with a 3D design, using the coordinate transformation technique and metamaterials. By structuring the thermal conductor, the desired local density-heat capacity product and anisotropic thermal conductivities were achieved. The homogenized thermal conductivities were obtained from finite element simulations and cylindrical symmetry consideration. A 3D concentrator was fabricated using 3D metal printing and characterized using a thermal camera. Compared to devices that solely consider anisotropic conductivities, the time evolution characteristics of the metadevice designed with coordinate transformation were closer to those of an ideal concentrator.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Jie Li, Dalin Zhang, Yubing Wang, Penglei Zhang, Guangya Zhu
Summary: This paper presents an experimental study of flow condensation of R134a in a multiport mini channel and a mini channel with pin fin array. The results show that the pin fin array significantly improves the condensation heat transfer coefficient, and the local heat transfer coefficient increases with vapor quality, mass flux, and heat flux while decreases with saturation pressure.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Shao-Fei Zheng, We-Kai Liana, Jia-Xing Meng, He-Chen Wang, Shu-Rong Gao, Yan-Ru Yang, Hai-Wang Li, Bengt Sunden, Xiao-Dong Wang
Summary: This study focuses on optimizing the rib arrangements in cooling passages of a turbine blade cooling unit to improve heat transfer performance. The multi-parameter optimization algorithm is applied to find the optimal designs with different performance indices as objective functions. The results show that using the overall performance factor as the objective function can achieve significant reduction in friction loss with moderate heat transfer loss.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Acoustics
Jiahui Peng, Liang Wang, Bochen Wang, Minjuan Yuan, Wei Xu
Summary: A new path integration method is proposed for stochastic dynamical systems excited by Poisson white noise. It constructs an efficient one-step transition probability density function matrix based on a decoupling probability mapping. The method can handle multiple impulses occurring in a one-step transition time interval and considers the randomness of the impulse instant.
JOURNAL OF SOUND AND VIBRATION
(2024)
Article
Acoustics
Yuhong Li, Zhida Ma, Peng Zhou, Siyang Zhong, Xin Zhang
Summary: In this study, we numerically investigate the aerodynamic and aeroacoustic performance of a hexacopter for urban air mobility. The results show that close placement of rotors leads to thrust fluctuations and increased sound pressure level. The presence of connecting arms generates additional noise, while the fuselage has little impact on total thrust and noise generation.
JOURNAL OF SOUND AND VIBRATION
(2024)
Article
Acoustics
Longkai Zheng, Fengming Li, Zhijing Wu, Shurui Wen
Summary: A novel strategy is proposed for the dynamic modelling and quality factor evaluation of hemispherical shell resonators (HSR) considering the coupling of hemispherical shell and support rod. The artificial spring technique is introduced to simulate arbitrary boundary conditions. Hamilton's principle with the Rayleigh-Ritz method is employed to establish the equation of motion and obtain the natural frequencies of the HSR. The thermal energy method is applied to evaluate the thermoelastic damping (TED) of the HSR. The model of anchor loss is based on a separation and transfer method. The present theoretical model is validated through comparisons with published literature and finite element method (FEM). The effects of boundary conditions, geometrical parameters, and material properties on the vibration behaviors and quality factors of the HSR are analyzed.
JOURNAL OF SOUND AND VIBRATION
(2024)
Article
Acoustics
N. Aberkane-Gauthier, V. Romero-Garcia, D. Lecoq, M. Moleron, C. Lagarrigue, C. Pezerat
Summary: The dispersion and scattering properties of a soft solid plate with solid cylindrical inclusions embedded in it are investigated theoretically and numerically in this study. The system takes into account both the vibroacoustic coupling and the presence of viscoelastic losses. The presence of the inclusions introduces resonant and antiresonant phenomena, leading to an elastic band-gap and destructive modal interference in the soft solid plate.
JOURNAL OF SOUND AND VIBRATION
(2024)
Article
Acoustics
Alexander N. Carr, Joel B. Lonzaga, Steven A. E. Miller
Summary: This study examines the effects of atmospheric boundary layer turbulence on the loudness variability of a sonic boom. The results show that the standard deviations of loudness metrics collapse across different convection levels of turbulence for small propagation distances. Additionally, the distribution of loudness metrics can be well approximated by a normal distribution for a given range of propagation distances and becomes increasingly skewed as distance increases.
JOURNAL OF SOUND AND VIBRATION
(2024)
Article
Acoustics
M. Amabili, H. R. Moghaddasi
Summary: Studies on nonlinear vibrations of circular cylindrical shells containing fluid have focused mostly on thin simply supported shells, leaving a lack of research on the behavior of thick cantilevered shells with shear and thickness deformations. This article presents, for the first time, models of thin and thick circular cylindrical shells with clamped-free boundary conditions based on the third-order shear deformation theory with thickness stretch. The derived governing differential equations describe the shell-fluid interaction. Results show that increasing the fluid level and decreasing the shell thickness in linear free vibration analysis significantly raise the fluid free-surface wave elevation, limiting the application of linear sloshing theory. The presence of the fluid changes the nonlinear behavior from softening to hardening, and intensifies the shell thickness deformation. Additionally, the contained liquid reduces the circumferential dynamic contraction caused by large amplitude vibrations.
JOURNAL OF SOUND AND VIBRATION
(2024)
