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  • Open Access

    ARTICLE

    DIAGNOSIS OF CENTRIFUGAL PUMP SPEED FLUCTUATION BY USING VORTEX DYNAMICS

    L. Chenga , Y. L. Zhanga,† , J. F. Lib

    Frontiers in Heat and Mass Transfer, Vol.19, pp. 1-7, 2022, DOI:10.5098/hmt.19.32

    Abstract The internal characteristics during rotational speed fluctuation have an important influence on centrifugal pump to avoid or utilize its transient performance. In this paper, a circulation piping system that includes a low-specific-speed centrifugal pump is established to study the energy distribution characteristics in a centrifugal pump during speed fluctuation. The unsteady flow in the entire system is numerically calculated with a user-defined function, the sliding grid method, and the RNG k-ε turbulence model. Then, the energy distribution of the transient flow field in the centrifugal pump model during speed fluctuation is diagnosed with vortex dynamics by using flow section and… More >

  • Open Access

    ARTICLE

    VISUALIZATION OF INDUCED COUNTER-ROTATING VORTICES FOR ELECTRIC VEHICLES BATTERY MODULE THERMAL MANAGEMENT

    A.C. Budimana,*, S. M. Hasheminejadb, Sudirjaa, A. Mitayanic, S. H. Winotod

    Frontiers in Heat and Mass Transfer, Vol.19, pp. 1-6, 2022, DOI:10.5098/hmt.19.9

    Abstract Streamwise development of counter-rotating vortices induced by three different types of chevron Vortex Generators (VGs) placed upstream an Electric Vehicles (EV) dummy battery module is experimentally visualized using a smoke-wire method. From the single chevron reference case, the mushroom-like vortices do not collapse until passing the module. When more chevrons are used in line, the vortices become more prominent. It can also be observed that the vortex sizes and shapes are significantly influenced by the spanwise base length of the chevron. The induced vortices from all three VGs suggest a potential heat transfer augmentation for the EV battery module application. More >

  • Open Access

    ARTICLE

    Generation of OAM Waves and Analysis of Mode Purity for 5G Sub-6 GHz Applications

    Shehab Khan Noor1, Arif Mawardi Ismail1, Mohd Najib Mohd Yasin1,*, Mohamed Nasrun Osman1, Nurulazlina Ramli2, Ali H. Rambe3, J. Iqbal4,5

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

    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 by measuring the null in… More >

  • Open Access

    ARTICLE

    Application of Vortex Generators to Remove Heat Trapped in Closed Channels

    Alim Al Ayub Ahmed1,*, Salim Oudah Mezan2, Binyamin3, Murtadha Doghiam Abdullah4, Elena Tesleva5, Linar G. Akhmetov6, Rustem Zalilov7, Mustafa M. Kadhim8,9,10, Abduladheem Turki Jalil11,12

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

    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 of generators increases the pressure… More >

  • Open Access

    ARTICLE

    A Numerical Study on Supersonic Combustion Optimization Based on the Streamwise Vortex-Couple Method

    Hao Tian, Yongkang Zheng*, Hanxin Zhang

    FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.1, pp. 207-222, 2023, DOI:10.32604/fdmp.2023.019790

    Abstract In this paper, some typical methods to promote mixing in supersonic combustion are reviewed, and the fluid-dynamic mechanism underpinning the development of the supersonic shear layer in the presence of a streamwise vortex is analyzed through computational fluid dynamics. It is proven that the streamwise vortex-couple method is an excellent approach to enhance mixing. A specific combustor design is proposed accordingly. More >

  • Open Access

    ARTICLE

    Study on the Influence of a Wake Vortex on an ARJ21 Aircraft Using the Strip Method

    Weijun Pan*, Jingkai Wang, Hao Wang, Yuming Luo

    FDMP-Fluid Dynamics & Materials Processing, Vol.18, No.5, pp. 1495-1509, 2022, DOI:10.32604/fdmp.2022.019018

    Abstract A model for the vortex distribution in the wake of an aircraft is elaborated to investigate the wake influence on the behaviour of other aircrafts potentially interacting with it. As a realistic case, the interaction of an ARJ21 aircraft with a (leading) A330-200 aircraft is considered. Different distances are considered, namely, 6 km, 7 km, 8 km, 9.3 km, and 10 km. Simulations based on the used wake dissipation mechanism are used to investigate different conditions, namely, the ARJ21 in take-off and level flight and the changes induced in the related lift by the front aircraft A330-200 during landing. The… More > Graphic Abstract

    Study on the Influence of a Wake Vortex on an ARJ21 Aircraft Using the Strip Method

  • Open Access

    ARTICLE

    How Do Water Filled Traffic Barriers Shake a Suspension Bridge?

    Guanni Qu1,#, Tianai Yue2,#,*, Xiaoyu Zhang3, Shibiao Wei3

    FDMP-Fluid Dynamics & Materials Processing, Vol.18, No.3, pp. 591-608, 2022, DOI:10.32604/fdmp.2022.017776

    Abstract The present study stems from the realization that the general problem relating to the analysis of wind-induced vibrations in suspension bridges still requires significant attention. Sidewalk railings, overhaul tracks, and deflectors are known to largely affect such dynamics. Here, the influence of a row of water-filled traffic barriers on the response of a sample suspension bridge is investigated numerically. It is shown that the existence of water barriers causes flow separation and non-negligible vortices with respect to the condition with no water barriers. The vortex shedding frequency at the far end is around 41.30 Hz, relatively close to the real… More >

  • Open Access

    ARTICLE

    Numerical Investigation on the Aerodynamic Noise Generated by a Simplified Double-Strip Pantograph

    Jiawei Shi1, Shuai Ge1, Xiaozhen Sheng2,*

    FDMP-Fluid Dynamics & Materials Processing, Vol.18, No.2, pp. 463-480, 2022, DOI:10.32604/fdmp.2022.017508

    Abstract In order to understand the mechanism by which a pantograph can generate aerodynamic noise and grasp its far-field characteristics, a simplified double-strip pantograph is analyzed numerically. Firstly, the unsteady flow field around the pantograph is simulated in the frame of a large eddy simulation (LES) technique. Then the location of the main noise source is determined using surface fluctuating pressure data and the vortex structures in the pantograph flow field are analyzed by means of the Q-criterion. Based on this, the relationship between the wake vortex and the intensity of the aerodynamic sound source on the pantograph surface is discussed.… More >

  • Open Access

    ARTICLE

    Numerical Simulation of Wake Vortices Generated by an A330-200 Aircraft in the Nearfield Phase

    Xuan Wang, Weijun Pan*

    FDMP-Fluid Dynamics & Materials Processing, Vol.18, No.1, pp. 173-188, 2022, DOI:10.32604/fdmp.2022.017869

    Abstract In order to overcome the typical limitation of earlier studies, where the simulation of aircraft wake vortices was essentially based on the half-model of symmetrical rectangular wings, in the present analysis the entire aircraft (a typical A330-200 aircraft) geometry is taken into account. Conditions corresponding to the nearfield phase (take-off and landing) are considered assuming a typical attitude angle of 7° and different crosswind intensities, i.e., 0, 2 and 5 m/s. The simulation results show that the aircraft wake vortices form a structurally eudipleural four-vortex system due to the existence of the sweepback angle. The vortex pair at the outer side… More >

  • Open Access

    ARTICLE

    Analysis of Flow Structure in Microturbine Operating at Low Reynolds Number

    Mohamed Omri1,*, Yusuf Al-Turki2, Ahmed A. Alghamdi1, Amrid Amnache3, Luc G. Fréchette3

    CMC-Computers, Materials & Continua, Vol.71, No.1, pp. 961-977, 2022, DOI:10.32604/cmc.2022.021406

    Abstract In this paper, three-dimensional flows in laminar subsonic cascades at relatively low Reynolds numbers (Re < 2500) are presented, based on numerical calculations. The stator and rotor blade designs are those for a MEMS-based Rankine microturbine power-plant-on-a-chip with 109-micron chord blades. Blade passage calculations in 3D were done for different Reynolds numbers, tip clearances (from 0 to 20%) and incidences (0° to 15°) to determine the impact of aerodynamic conditions on the flow patterns. These conditions are applied to a blade passage for a stationary outer casing. The 3D blade passage without tip clearance indicates the presence of two large… More >

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