Article
Physics, Applied
M. D. Cunha, M. A. Sargsyan, M. Kh Gadzhiev, D. Tereshonok, M. S. Benilov
Summary: This article presents a modelling method for simulating the cathodic part of arc plasma torches. The method involves decoupling the simulation of the cathode and the near-cathode non-equilibrium plasma layer from the simulation of the whole arc. The method was validated by comparing it with experimental results on a DC arc in atmospheric-pressure argon.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2023)
Article
Mechanics
Firoozeh Yeganehdoust, Jack Hanson, Zachary Johnson, Mehdi Jadidi, Sara Moghtadernejad
Summary: The goal of this study is to investigate and analyze the dynamics of shear-driven droplet shedding and coalescence under various parameters. Experimental and numerical modeling were conducted to capture different aspects of droplet behavior. The results showed that droplet size, distance between droplets, surface wettability, and airflow velocity are crucial factors that influence droplet dynamics. The study also revealed differences in droplet behavior on hydrophilic and superhydrophobic surfaces. Further analysis of aerodynamic forces before and after coalescence was presented to better interpret droplet dynamics.
Article
Materials Science, Multidisciplinary
Conglin Yao, Zhouhua Jiang, Hongchun Zhu, Tao Pan
Summary: A 2D unified model was developed to analyze the characteristics of plasma arc-molten bath-cavity in a DC electric arc furnace, investigating the formation processes of the cavity, flow field, and heating rate of the molten bath. The numerical results showed three stages in cavity formation and two flow patterns inside the molten bath under plasma arc jet impingement.
Article
Engineering, Chemical
Ke Shao, Ya-Hao Hu, Xian Meng, He-Ji Huang, Su-Rong Sun, Hai-Xing Wang
Summary: The significance of the restrike mode in a DC arc device and its relation to operating conditions. Under fixed gas flow, the restrike frequency increases with arc current, while the voltage jump decreases; under fixed arc current, both frequency and jump increase with gas flow rates.
PLASMA CHEMISTRY AND PLASMA PROCESSING
(2021)
Article
Engineering, Marine
Jie Chen, Changli Hu, Mengjie Zhang, Biao Huang, Hanzhe Zhang
Summary: The objective of this study is to discuss a passive control method for different stages of cavitating flows. The study utilizes micro delta-shaped vortex generators inserted on the suction side of a hydrofoil to achieve passive flow control, and high-speed cameras are used to visualize the cavitating flow structures. The results show that different positions of the vortex generators lead to different cavitation modes, and a new cavitation mode is discovered.
Article
Physics, Applied
Qichen Ke, Yi Wu, Hailong He, Shaolun Dong, Yu Xiao, Fengfeng Jiang, Chunping Niu, Mingzhe Rong
Summary: An arc discharge in water can generate high voltage, showing great potential in DC fault protection. However, observing the arc shape directly is challenging due to the complex gas-liquid mixed environment. In this study, an observation device is designed to capture underwater arc motion, revealing the relationship between the arc behaviors and voltage variations. Additionally, the application of an external transverse magnetic field enables stable control of the random underwater arc behaviors, and the enhanced cooling mechanism and directional arc motion characteristics are discussed.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2023)
Article
Engineering, Multidisciplinary
Austin C. Gaunce, Xuan Wu, John D. Mandeville, Dennis J. Hoffman, Amrit S. Khalsa, Joseph Sottile, Ronald J. Wellman
Summary: Arc-flash is a major hazard associated with electrical systems, with most research focused on ac systems and less on dc systems which are becoming more common. Current dc arc-flash models are theoretical and lack empirical data, requiring further investigation. This article presents new models developed through empirical testing and explores the potential interactions between dc arc-flash and atmospheric conditions.
IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS
(2021)
Article
Engineering, Electrical & Electronic
Meng Wei, Jianlin Hu, Xiaofeng Wang, Xingliang Jiang, Ruihe Zhang, Lichun Shu
Summary: This study investigated the thermal characteristics of DC arcs on ice surfaces using a calibrated Schlieren system. Results found temperature jumps during spark discharge, followed by exponential increases with leakage current during arc formation. Gas composition in the arc channel differed from other regions, providing new insights into the partial arc formation process.
IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION
(2021)
Article
Physics, Applied
Hui Li, Chengxun Yuan, Anatoly Kudryavtsev, Aleksandr Astafiev, Evgeny Bogdanov, T. Yasar Katircioglu, Ismail Rafatov
Summary: This study investigates atmospheric pressure dielectric barrier discharges (DBDs) through numerical and experimental methods. Experimental measurements are made on the current and voltage of DBDs sustained in an argon flow in a coaxial discharge cell. Numerical models are based on drift-diffusion theory and different modeling approaches are implemented, considering electron kinetics based on Maxwellian electron energy distribution function (EEDF) as well as more realistic EEDF obtained from the solution of the electron Boltzmann equation, while also taking into account energy loss due to gas heating.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Engineering, Electrical & Electronic
Haining Wang, Xiaozhou Wang, Tao Fan, Jian Wang, Zijie Lin, Yu Shen, Jianhui Su, Peng Zhang
Summary: This article proposes a low-cost, simple, reliable, and effective method for detecting DC series arc faults, based on the study of common-mode conductive voltage signals produced by arc faults. Through experimental verification, the proposed method has been shown to be effective and resistant to interference.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2022)
Article
Engineering, Electrical & Electronic
Hwa-Pyeong Park, Mina Kim, Suyong Chae
Summary: This study focuses on the detection of DC arc faults to enhance the reliability of renewable energies and energy storage systems. The proposed control algorithm of the DC optimizer is capable of detecting and extinguishing series arc fault conditions between the PV panel and DC optimizer, considering the characteristics of both the PV panel and the arc fault. The validity of the algorithm has been verified through simulation and experimental results.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2022)
Article
Physics, Applied
Hideto Takasawa, Yusuke Takahashi, Nobuyuki Oshima, Hisashi Kihara
Summary: The experimental study verified the effectiveness of using surface catalysis effect to mitigate reentry blackout, showing that high catalytic wall was more efficient in preventing communication blackout compared to low catalytic wall.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2021)
Article
Engineering, Mechanical
Hong-Cheol Shin, Santhosh Senguttuvan, Sung-Min Kim
Summary: This study investigates the stable and unstable slug flow in micro-channels through experiments and measurements, and identifies the fundamental characteristics of different types of slug flow. The analysis of pressure data reveals a correlation between pressure fluctuation and morphological characteristics of the slug flow.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2023)
Article
Energy & Fuels
Julio Jose Caparros Mancera, Jaime Luis Saenz, Eduardo Lopez, Jose Manuel Andujar, Francisca Segura Manzano, Francisco Jose Vivas, Fernando Isorna
Summary: This paper presents a comprehensive experimental analysis on the influence of using supercapacitor banks as energy storage system in renewable energy sources-based microgrids with high voltage DC bus. The results demonstrate that the supercapacitor banks provide a smooth dynamic response, more efficient and flexible power management, and greater voltage stability, while also protecting the equipment from current peaks.
Article
Engineering, Multidisciplinary
Samet Yalcin, Tuna Goksu, Selami Kesler, Okan Bingol
Summary: Dual active bridge DC-DC converters (DAB) are bidirectional converters used in electric vehicles and micro grids. The importance of DAB converters has increased due to the growing number of electric vehicles and micro grids. Increasing the switching frequency can improve efficiency and power density, but it also leads to increased electromagnetic interference (EMI). This study evaluates the EMI emitted by DAB converters with different phase shift modulation methods and MOSFET types. The findings show that the choice of modulation method and MOSFET type can affect the EMI and efficiency of the circuits.
ENGINEERING SCIENCE AND TECHNOLOGY-AN INTERNATIONAL JOURNAL-JESTECH
(2023)
Article
Engineering, Aerospace
Paht Juangphanich, Guillermo Paniagua
Summary: This paper investigates the flow field in the rotor-stator rim cavity and presents a reduced-order approach to optimize the cavity geometry. Two parameterization strategies are used with a genetic optimizer to maximize thermal protection and minimize cooling massflow required. The optimal geometries are found to be sensitive to variations in the axial gap and purge coolant total pressure.
INTERNATIONAL JOURNAL OF TURBO & JET-ENGINES
(2023)
Article
Engineering, Electrical & Electronic
Patrick Krane, David Gonzalez Cuadrado, Francisco Lozano, Guillermo Paniagua, Amy Marconnet
Summary: This paper evaluates two methods for reducing computation time in estimating heat generation within electronics packages. The methods use a sensitivity-coefficient method and achieve a balance between computation time reduction and accuracy, making them convenient for designing and testing electronics packages.
JOURNAL OF ELECTRONIC PACKAGING
(2022)
Article
Engineering, Mechanical
Lakshya Bhatnagar, Guillermo Paniagua, David G. Cuadrado, Papa Aye N. Aye-Addo, Antonio Castillo Sauca, Francisco Lozano, Matthew Bloxham
Summary: This paper presents an uncertainty analysis of loss measurements in a high-pressure turbine vane, providing recommendations for correction. The research aims to provide accurate experimental measurement methods and data for turbine development.
JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER-TRANSACTIONS OF THE ASME
(2022)
Article
Engineering, Aerospace
Jorge Saavedra, Guillaume Grossir, Olivier Chazot, Guillermo Paniagua
Summary: This paper analyzes the nozzle start-up of the von Karman Institute Longshot, an impulse hypersonic gun tunnel, using the Lagrangian L1D code and unsteady Reynolds-averaged Navier-Stokes simulations. The study investigates the influence of initial nozzle flow conditions on start-up duration and verifies that the shortest establishment time occurs at the lowest initial pressure. The paper also presents criteria for flow establishment and quasi-steady behavior based on the evolution of freestream static pressure and temperature.
Article
Engineering, Aerospace
Kotaro Nakata, Kosei Ota, Shiro Ito, Kazuki Ishihara, Keisuke Goto, Noboru Itouyama, Hiroaki Watanabe, Akira Kawasaki, Ken Matsuoka, Jiro Kasahara, Akiko Matsuo, Ikkoh Funaki, Kazuyuki Higashino, James Braun, Terrence Meyer, Guillermo Paniagua
Summary: Converging-diverging nozzles are commonly used in rocket engines to increase exhaust velocity. This study focuses on accelerating subsonic burned gas without a throat via detonation to create a compact engine. The researchers developed and tested a rotating detonation engine without a throat and with a constant diverging angle, achieving supersonic exhaust flow.
Article
Engineering, Aerospace
Jorge Sousa, Elena Collado-Morata, Guillermo Paniagua
Summary: This paper presents a design methodology for turbine stages suitable for supersonic inlet conditions and provides a detailed analysis of optimized turbine geometries. Shock-wave interactions are identified as the main contributors to turbine losses, and optimal pitch-chord ratios and metal angles are calculated for maximizing power extraction.
CHINESE JOURNAL OF AERONAUTICS
(2022)
Article
Thermodynamics
Venkat Athmanathan, James Braun, Zachary M. Ayers, Christopher A. Fugger, Austin M. Webb, Mikhail N. Slipchenko, Guillermo Paniagua, Sukesh Roy, Terrence R. Meyer
Summary: The study investigates non-premixed rotating detonation combustors using advanced diagnostic techniques and numerical simulations. A dual-wave system composed of leading and trailing detonation waves is observed in annular geometries and its behavior is explained by local flow physics. Furthermore, the study reveals the significant influence of reactant inlet conditions in the near-field and far-field regions on system structure and combustion efficiency.
COMBUSTION AND FLAME
(2022)
Article
Computer Science, Interdisciplinary Applications
Francisco Lozano, Iman Rahbari, Guang Lin, Guillermo Paniagua
Summary: This study investigates the robustness of leading edge blowing for active control of the upstream bow shock and overall aerothermal characteristics of a supersonic airfoil with variability in the injection conditions. The uncertain boundary conditions lead to significant variations in flow topology, particularly at the injection exit and bow shock position. The study identifies the key operating conditions for optimal application of leading-edge injection for active control of supersonic airfoils.
COMPUTERS & FLUIDS
(2022)
Article
Thermodynamics
James Braun, Francois Falempin, Guillermo Paniagua
Summary: This paper introduces an energy conversion unit that can extract power and increase thrust from high subsonic to hypersonic flows. The energy transfer is achieved through a wavy hub surface, and the feasibility of this technology is verified through numerical simulations and cycle analysis. Furthermore, energy extraction from the highly unsteady exhaust of rotating detonation combustors without an additional intermediate diffuser or nozzle is also demonstrated.
ENERGY CONVERSION AND MANAGEMENT
(2022)
Article
Chemistry, Multidisciplinary
Carlos Carbajosa, Alejandro Martinez-Cava, Eusebio Valero, Guillermo Paniagua
Summary: This study investigates the use of base bleed as a flow control tool to modulate the flow between turbine blade rows. The results demonstrate that pulsating bleed flow is more efficient than steady flow in terms of reducing pressure losses and controlling the primary frequency of downstream oscillations.
APPLIED SCIENCES-BASEL
(2022)
Article
Engineering, Aerospace
Bora O. Cakir, Ali Can Ispir, Bayindir H. Saracoglu
Summary: This study introduces a reduced order holistic approach for design and assessment of high-speed propulsion systems, focusing on ramjet/scramjet engines. By validating and verifying the simplified model, parameters such as fuel consumption, thrust, and specific impulse are calculated to evaluate engine performance.
Article
Mechanics
Francisco Lozano, Jorge Saavedra, Guillermo Paniagua
Summary: This study evaluates the use of active flow control to mitigate the aerothermal penalties caused by blunt fin-induced shock wave-boundary layer interaction. Computational fluid dynamics simulations were used to analyze the effect of flow injection and investigate the flow topology and wall variables. The study provides insights into the structures and development of low-frequency shock motion caused by the shock wave-boundary layer interaction.
Article
Physics, Fluids & Plasmas
Hugo F. S. Lui, Tulio R. Ricciardi, William R. Wolf, James Braun, Iman Rahbari, Guillermo Paniagua
Summary: The physics of shock-boundary layer interactions in a supersonic turbine cascade are investigated using wall-resolved large eddy simulation. The characteristics of separation bubbles, including low-frequency dynamics, are analyzed through various methods. The study reveals similarities and discrepancies compared to canonical cases.
PHYSICAL REVIEW FLUIDS
(2022)
Article
Engineering, Aerospace
Ali C. Ispir, Kamila Zdybal, Bayindir H. Saracoglu, Thierry Magin, Alessandro Parente, Axel Coussement
Summary: Dual-mode ramjet/scramjet engines are commonly preferred air-breathing propulsion systems for hypersonic aircraft. Modeling the fuel-air mixing process is a main challenge in their design to optimize engine performance. Machine learning models, such as artificial neural networks, can be used for multi-objective optimization of design variables. Experimental data can be used to build regression models that predict mixing conditions in reduced-order modeling studies for estimating engine performance.
Article
Thermodynamics
Konstantin Huber, Tim Roediger, Lakshya Bhatnagar, Guillermo Paniagua
Summary: This paper compares the calibration of different heat flux sensors in radiation and convection-based sub- and supersonic operation. The results show that using radiative calibrated sensors in a mainly convective environment can lead to significant systematic errors. However, calibration in a subsonic shear flow with thermocouple readings demonstrates small divergence from the manufacturer provided sensitivity. Additionally, supersonic testing with high frequency shock-boundary layer interactions highlights the necessity of using ALTP to resolve the associated high frequency phenomena.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2023)
