Bo Hui^1,2,*, Shengneng Zhu², Sijun Su², Wenjuan Li²

Frontiers in Heat and Mass Transfer, Vol.22, No.3, pp. 855-868, 2024, DOI:10.32604/fhmt.2024.051387 - 11 July 2024

Abstract The structure of the concave-convex plates has proven to be crucial in optimizing the internal flow characteristics of the electrolyzer for hydrogen production. This paper investigates the impact of the gradual expansion angle of the inlet channel on the internal flow field of alkaline electrolyzers. The flow distribution characteristics of concave-convex plates with different inlet angle structures in the electrolytic cell is discussed. Besides, the system with internal heat source is studied. The results indicate that a moderate gradual expansion angle is beneficial for enhancing fluid uniformity. However, an excessively large gradual expansion angle may More > Graphic Abstract

Ghobad Shafiei Sabet^1,*, Ali Sari¹, Ahmad Fakhari^2,*, Nasrin Afsarimanesh³, Dominic Organ⁴, Seyed Mehran Hoseini¹

Frontiers in Heat and Mass Transfer, Vol.22, No.2, pp. 491-509, 2024, DOI:10.32604/fhmt.2024.048290 - 20 May 2024

Abstract This study conducts both numerical and empirical assessments of thermal transfer and fluid flow characteristics in a Solar Air Collector (SAC) using a Delta Wing Vortex Generator (DWVG), and the effects of different height ratios (R = 0.6, 0.8, 1, 1.2 and 1.4) in delta wing vortex generators, which were not considered in the earlier studies, are investigated. Energy and exergy analyses are performed to gain maximum efficiency. The Reynolds number based on the outlet velocity and hydraulic diameter falls between 4400 and 22000, corresponding to the volume flow rate of 5.21–26.07 m/h. It is More >

Wei Guo¹, Yanliang Liu¹, Xuqiang Wang¹, Jiazheng Meng², Mengqin Hu², Bo He^2,*

Structural Durability & Health Monitoring, Vol.18, No.1, pp. 19-35, 2024, DOI:10.32604/sdhm.2023.042944 - 11 January 2024

Abstract As an important lightning protection device in substations, lightning rods are susceptible to vibration and potential structural damage under wind loads. In order to understand their vibration mechanism, it is necessary to conduct flow analysis. In this study, numerical simulations of the flow field around a 330 kV cylindrical lightning rod with different diameters were performed using the SST k-ω model. The flow patterns in different segments of the lightning rod at the same reference wind speed (wind speed at a height of 10 m) and the flow patterns in the same segment at different reference wind… More >

Tian Li^1,2,*, Hao Liang¹, Zerui Xiang², Jiye Zhang¹

FDMP-Fluid Dynamics & Materials Processing, Vol.20, No.2, pp. 463-473, 2024, DOI:10.32604/fdmp.2023.043618 - 14 December 2023

Abstract A relatively high aerodynamic drag is an important factor that hinders the further acceleration of high-speed trains. Using the shear stress transport (SST) k-ω turbulence model, the effect of various vortex generator types on the aerodynamic characteristics of an ICE2 (Inter-city Electricity) train has been investigated. The results indicate that the vortex generators with wider triangle, trapezoid, and micro-ramp arranged on the surface of the tail car can significantly change the distribution of surface pressure and affect the vorticity intensity in the wake. This alteration effectively reduces the resistance of the tail car. Meanwhile, the micro-ramp More > Graphic Abstract

Jiefeng Wang¹, Eddie Yin Kwee Ng^2,*, Jianwu Li¹, Yanhao Cao¹, Yanan Huang¹, Liang Li^1,2,3,*

Frontiers in Heat and Mass Transfer, Vol.21, pp. 1-31, 2023, DOI:10.32604/fhmt.2023.045510 - 30 November 2023

Abstract The flow structure of the vortex cooling is asymmetrical compared to the traditional gas turbine leading edge cooling, such as the impingement cooling and the axial flow cooling. This asymmetrical property will affect the cooling performance in the blade leading edge, whereas such effects are not found in most of the studies on vortex cooling due to the neglect of the mainstream flow in the airfoil channel. This study involves the mainstream flow field and the rotational effects based on the profile of the GE E³ blade to reveal the mechanism of the asymmetrical flow structure… More > Graphic Abstract

Amnart Boonloi¹, Withada Jedsadaratanachai^2,*

Frontiers in Heat and Mass Transfer, Vol.21, pp. 317-336, 2023, DOI:10.32604/fhmt.2023.044929 - 30 November 2023

Abstract Thermal performance enhancement in a square channel heat exchanger (HX) using a passive technique is presented. Vortex turbulator insertion in a square channel HX as a passive technique is selected for thermal improvement. The vortex turbulator of interest is discrete X-V baffles (XVB). The discrete XVBs are inserted in the square channel with the main aim of generating vortex flow. The vortex flow generated can support the enhanced convective heat transfer coefficient and also enhance HX performance. Effects of baffle configuration (type A and B), baffle size (w/H = 0.05, 0.10, 0.15 and 0.20), baffle… More > Graphic Abstract

Karema A. Hamad^*, Yasser A. Mahmood

FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.11, pp. 2863-2875, 2023, DOI:10.32604/fdmp.2023.029049 - 18 September 2023

Abstract The cooling of a (pebble bed) spent fuel in a high-temperature gas-cooled reactor (HTGR) is adversely affected by an increase in the temperature of the used gas (air). To investigate this problem, a configuration consisting of three copper spheres arranged in tandem subjected to a forced mist flow inside a cylindrical channel is considered. The heat transfer coefficients and related variations as a function of Reynolds number are investigated accordingly. The experimental results show that when compared to those with only airflow, the heat transfer coefficient of the spherical elements with mist flow (j = More >

Shehab Khan Noor¹, Arif Mawardi Ismail¹, Mohd Najib Mohd Yasin^1,*, Mohamed Nasrun Osman¹, Thennarasan Sabapathy¹, Shakhirul Mat Salleh², Ping Jack Soh³, Ali Hanafiah Rambe⁴, Nurulazlina Ramli⁵

Computer Systems Science and Engineering, Vol.47, No.1, pp. 537-551, 2023, DOI:10.32604/csse.2023.037381 - 26 May 2023

Abstract This paper presents a flexible and wearable textile array antenna designed to generate Orbital Angular Momentum (OAM) waves with Mode +2 at 3.5 GHz (3.4 to 3.6 GHz) of the sub-6 GHz fifth-generation (5G) New Radio (NR) band. The proposed antenna is based on a uniform circular array of eight microstrip patch antennas on a felt textile substrate. In contrast to previous works involving the use of rigid substrates to generate OAM waves, this work explored the use of flexible substrates to generate OAM waves for the first time. Other than that, the proposed antenna… More >

Shehab Khan Noor¹, Arif Mawardi Ismail¹, Mohd Najib Mohd Yasin^1,*, Mohamed Nasrun Osman¹, Nurulazlina Ramli², Ali H. Rambe³, J. Iqbal^4,5

CMC-Computers, Materials & Continua, Vol.74, No.1, pp. 2239-2259, 2023, DOI:10.32604/cmc.2023.031170 - 22 September 2022

Abstract This article presents the generation of Orbital Angular Momentum (OAM) vortex waves with mode 1 using Uniform Circular Array (UCA) antenna. Two different designs, namely, UCA-1 (4-element array antenna) and UCA-2 (8-element array antenna), were designed and fabricated using FR-4 substrate to generate OAM mode 1 at 3.5 GHz (5G mid-band). The proposed antenna arrays comprised rectangular microstrip patch elements with inset fed technique. The elements were excited by a carefully designed feeding phase shift network to provide similar output energy at output ports with desired phase shift value. The generated OAM waves were confirmed… More >

Alim Al Ayub Ahmed^1,*, Salim Oudah Mezan², Binyamin³, Murtadha Doghiam Abdullah⁴, Elena Tesleva⁵, Linar G. Akhmetov⁶, Rustem Zalilov⁷, Mustafa M. Kadhim^8,9,10, Abduladheem Turki Jalil^11,12

FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.1, pp. 15-24, 2023, DOI:10.32604/fdmp.2022.019922 - 02 August 2022

Abstract The utilization of vortex generators to increase heat transfer from cylinders installed inside a duct is investigated. In particular, a channel containing eight cylinders with volumetric heat sources is considered for different values of the Reynolds number. The effective possibility to use vortex generators with different sizes to increase heat transfer and, consequently, reduce the surface temperature of the cylinders is examined. Also, the amount of pressure drop inside the channel due to the presence of vortex generators is considered and compared with the cases without vortex generators. The results show that although the addition More >