Article
Engineering, Aerospace
Jian Zhai, Chen-An Zhang, Fa-Min Wang, Wei-Wei Zhang
Summary: This paper presents a new method to control the shock-wave/boundary-layer interaction using a backward-facing step. The backward-facing step effectively suppresses flow separation by replacing the strong shock-wave with weaker ones. Numerical analysis shows that only the effective wave system can suppress the shock-wave/boundary-layer interaction. Parameter study is conducted to analyze the effect of the design parameters on the control ability.
AEROSPACE SCIENCE AND TECHNOLOGY
(2022)
Article
Mechanics
Pititat Itsariyapinyo
Summary: This paper explores the possibility of visualizing low-speed, near-wall flow using schlieren imaging technique. Wind tunnel testing is conducted on a backward-facing step at different Reynolds numbers. The study finds that it is important to reduce the interference to the flow field during visualization and achieve the required visibility for characterizing the flow field.
Article
Mechanics
Petteri Peltonen, Pekka Kanninen, Erkki Laurila, Ville Vuorinen
Summary: The study on wave formation behind the free surface backward facing step (FSBFS) shows that the wave shape cannot be solely characterized by the Froude number. Different conditions of step draught and inflow boundary layer profiles lead to variations in wave characteristics.
Article
Thermodynamics
Abd Rahim Abu Talib, Ali Kareem Hilo
Summary: The study found that combining a corrugated wall with a BFS channel can significantly enhance heat transfer, but also increases friction. The channel with a 4mm amplitude height and 20mm wavelength performed the best at 5000 Re, reaching a performance evaluation criterion factor of 1.33.
CASE STUDIES IN THERMAL ENGINEERING
(2021)
Article
Thermodynamics
Ayad S. Abedalh, Zaid A. Shaalan, Husam Naufal Saleh Yassien
Summary: The experimental study on convective heat transfer flow of hybrid nanofluids over a backward facing step in a heated rectangular duct under laminar flow showed significant enhancement in heat transfer and pressure drop using a mixture of Al2O3 and TiO2 solid nanoparticles in pure water. The results indicated that the Nusselt number increases with higher Reynolds number and mass fraction, while the friction factor decreases under these conditions. Enhancements of heat transfer and pressure drop were approximately 14% and 4% respectively.
CASE STUDIES IN THERMAL ENGINEERING
(2021)
Article
Engineering, Multidisciplinary
Mohamad Klazly, Gabriella Bognar
Summary: This study numerically investigates laminar flow in a micro-sized backward-facing step channel for water-based nanofluids. The impact of temperature differences between the inlet and the downward wall temperatures is also studied. The results show that increasing the concentration of nanoparticles can enhance the velocity and shear stress, as well as improve the heat transfer rate. However, a high volume fraction of nanoparticles decreases the performance efficiency.
ALEXANDRIA ENGINEERING JOURNAL
(2022)
Article
Thermodynamics
Thomas McQueen, David Burton, John Sheridan, Mark C. Thompson
Summary: This work provides new insight into the transient flow effects of forcing a backward-facing step flow at high Reynolds number. Notably, this research considerably extends the Reynolds number ranges of previous studies and examines the effect of periodic shear-layer forcing on the global mean and fluctuating flow structure. The study also investigates the influence of forcing on the distribution of key instabilities in the flow.
INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW
(2022)
Article
Mathematics, Applied
Yadong Huang, Desheng Zhang, Fadong Gu
Summary: The study investigated the effect of a streamwise Lorentz force applied in the primary and secondary separation bubbles on the base flow and the amplification rate of perturbation energy. The results showed that the convective term promotes the growth rate while the viscous term usually plays a suppressing role.
APPLIED MATHEMATICS AND MECHANICS-ENGLISH EDITION
(2021)
Article
Thermodynamics
Cong Qi, Zi Ding, Jianglin Tu, Yuxing Wang, Yinjie Wang
Summary: The study found that increasing the number of steps will increase the Nu value of the downstream wall of the steps. The increase in flow velocity has the greatest influence on the Nu value of the lower wall of the step, and the heat exchange effect of the hybrid nanofluids is better than that of water.
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
(2021)
Article
Thermodynamics
Yan Zhang, Kai Yue, Xinru Zhang, Xinxin Zhang
Summary: Investigation of the mechanism of particle transport and deposition in backward-facing step (BFS) flow is important for understanding fly ash deposition in radiant syngas cooler (RSC). This study used numerical simulation to deeply study the regional characteristics of particle deposition in BFS and RSC. The results showed that small particles were promoted to deposit in the recirculation (RC) zone and reattachment and redevelopment (RR) zone, while large particles were inhibited in the RC zone. The differences in particle deposition rates and size distributions between the two zones in RSC were also analyzed.
CASE STUDIES IN THERMAL ENGINEERING
(2023)
Article
Mechanics
Weibo Hu, Stefan Hickel, Bas W. van Oudheusden
Summary: The flow over a forward-facing step at Ma(infinity) = 1.7 and Re-delta 0 = 1.3718 x 10(4) was investigated using large-eddy simulation. The study compared the effects of laminar inflow and turbulent inflow on the dynamics of the shock wave/boundary layer interaction. The results showed that in the turbulent inflow case, the separation shock and Gortler-like vortices were strongly correlated with low-frequency unsteadiness.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Acoustics
Chung-Hao Ma, Manuj Awasthi, Danielle Moreau, Con Doolan
Summary: This paper presents a combined experimental and numerical study on the aeroacoustics of low Mach number turbulent flow over a forward-backward facing step (FBS). The study investigates the influence of step length and aspect ratio on wall pressure fluctuations and noise production. The results show that the largest wall pressure fluctuations occur slightly downstream of the step leading edge and turbulence interactions contribute to the wall pressure fluctuations in the on-step reattachment region. Aeroacoustic beamforming results show that the dominant noise source is located at the step leading edge.
JOURNAL OF SOUND AND VIBRATION
(2023)
Article
Engineering, Aerospace
Yaozhi Zhou, Zun Cai, Qinglian Li, Chenyang Li, Mingbo Sun, Shaotian Gong
Summary: This study experimentally investigated the effects of the backward-facing step and injection schemes on the spray characteristics of a liquid jet in a tandem backward-facing step cavity for the first time. High-speed photography and Schlieren techniques were used to accurately capture the instantaneous structures of the spray and wave structures of the air-flow field. The study revealed complex wave structures in the tandem backward-facing step cavity and found that the injection scheme near the upstream inlet had a higher penetration depth but lower spray distribution for the short cavity, while the injection scheme near the cavity had more spray distribution. For the long cavity, both the injection scheme near the upstream inlet and near the sharp corner of the backward-facing step had better spray distribution. The optimized injection scheme for the long backward-facing step cavity-based combustor is the upstream wall transverse injection, which improves both penetration and spray distribution.
AEROSPACE SCIENCE AND TECHNOLOGY
(2023)
Article
Physics, Multidisciplinary
Ya-Dong Huang, Jia-Wei Fu, Long-Miao Chen
Summary: In this study, tile-type and stripe-type electromagnetic actuators were employed to actively control perturbation energy in the liquid metal flow. Three control strategies were considered to change the amplification rate of the perturbation energy. The combined model control successfully altered the flow instability of the liquid metal flow.
Article
Engineering, Aerospace
Mingjiang Liu, Mingbo Sun, Daoning Yang, Guoyan Zhao, Tao Tang, Bin An, Hongbo Wang
Summary: Numerical investigation is conducted to study the mixing and combustion characteristics in a cavity flameholding combustor with ethylene injection at an inlet Mach number of 2.92. Different modes including the cavity shear-layer mode, lifted cavity shear-layer mode, and jet wake mode are observed at various dimensionless distances. The results are validated by experimental observations and show that the Backward-Facing Step (BFS) can promote flow separation downstream, and a reasonable distance can reduce total pressure loss and improve thrust performance in the combustion system.
CHINESE JOURNAL OF AERONAUTICS
(2023)
Article
Chemistry, Multidisciplinary
Husam Abdulrasool Hasan, Jenan S. Sherza, Azher M. Abed, Hussein Togun, Nidhal Ben Khedher, Kamaruzzaman Sopian, Jasim M. Mahdi, Pouyan Talebizadehsardari
Summary: This article investigates the influence of including transverse ribs within the absorber tube in the concentrated linear Fresnel collector system on thermal and flow performance coefficients. Simulations were conducted using water as the heat transfer fluid and the results showed that the inclusion of transverse ribs significantly enhanced heat transfer rates. The average Nusselt number increased by approximately 115% at Re = 5,000 and 175% at Re = 13,000 when compared to the plain absorber tube.
FRONTIERS IN CHEMISTRY
(2023)
Article
Thermodynamics
S. Hamidatou, M. Nadir, Hussein Togun, Azher M. Abed, K. Deghoum, A. Hadjad, Goodarz Ahmadi
Summary: This study investigates the heat transfer enhancement in a novel Helicoidal Square-Shaped Heat Exchanger with and without the use of nanofluids. The results show that increasing the nanofluid concentration and flow Reynolds number improves the heat transfer rate. The highest heat transfer ratio, heat transfer rate, heat transfer coefficient, and Nusselt number were achieved at a Reynolds number of 8000 and a nanofluid concentration of 0.5%. The use of Al2O3-water nanofluids is recommended to improve the efficiency of renewable energy plants.
HEAT AND MASS TRANSFER
(2023)
Article
Thermodynamics
Husam Abdulrasool Hasan, Hussein Togun, Azher M. Abed, Hayder I. Mohammed
Summary: The study investigated the impact of different slant angles and mass flow rates on the thermal efficiency of finned plate solar air heaters. The results showed that the thermal efficiency increased as the slant angle decreased, with the highest thermal efficiency achieved at a slant angle of 30 degrees and mass flow rate of 0.052 kg center dot s(-1).
INTERNATIONAL JOURNAL OF THERMOPHYSICS
(2023)
Article
Engineering, Chemical
Shadma Tasneem, Hakim S. Sultan, Abeer Ali Ageeli, Hussein Togun, Waleed M. Alamier, Nazim Hasan, Mohammad Reza Safaei
Summary: In this study, five powerful machine learning algorithms, including K-nearest neighbors (KNN), least absolute shrinkage and selection operator (LASSO), extreme gradient boosting (XGBoost), support vector machines (SVM) and Bayesian ridge accurate models, were used to predict the dynamic behavior of a reversible thermochemical reactions based system. The results showed that using polynomial regression and XGBoost algorithm provided the best predictions for NH4NO3 and KOH temperatures.
JOURNAL OF THE TAIWAN INSTITUTE OF CHEMICAL ENGINEERS
(2023)
Article
Multidisciplinary Sciences
Hussein Togun, S. Hamidatou, Hayder I. Mohammed, Azher. M. Abed, Husam Abdulrasool Hasan, Raad Z. Homod, Ali Wadi Al-Fatlawi, Mohaimen Al-Thamir, Tuqa Abdulrazzaq
Summary: This study investigates the thermal behavior and aerodynamic phenomena in a heated channel with varied rib configurations using computational fluid dynamics simulations. Incorporating ribs in such systems enhances heat transfer but increases flow resistance and manufacturing costs. Understanding heat exchanger theory, measurement methods, and numerical calculations are crucial for creating efficient heat exchangers.
Article
Multidisciplinary Sciences
Husam Abdulrasool Hasan, Hussein Togun, Azher M. Abed, Naef A. A. Qasem, Hayder I. Mohammed, Aissa Abderrahmane, Kamel Guedri, El Sayed M. Tag-ElDin
Summary: In this work, an innovative cooling system is utilized to minimize the temperature of lithium-ion battery cells (LiBs) and improve their performance, safety, and cycle life. The Finite Volume Method (FVM) is used to solve the continuity, momentum, and energy equations, and the computational fluid dynamics software ANSYS Fluent is employed to analyze the thermal management system for 52 LiB cells. The arrangement of batteries leads to symmetrical flow and temperature distribution in the battery pack. SiO2 distributed in water is investigated, and SiO2 nanofluid with a volume fraction of 5% shows the lowest average temperature values at all investigated Reynolds numbers. The innovative cooling system enhances the cooling process by increasing SiO2 concentrations, and a concentration of 5 vol% is recommended for better thermal diffusion and effective thermal conductivity. Increasing the Reynolds number increases flow turbulence and significantly enhances the heat transfer process.
Article
Energy & Fuels
Abdullah Bahlekeh, Hosseinali Ramezani Mouziraji, Hussein Togun, Abolfazl Ebrahimnataj Tiji, Azher M. Abed, Hayder I. Mohammed, Raed Khalid Ibrahem, Muataz S. Alhassan, Pouyan Talebizadehsardari
Summary: This study numerically analyzed the impact of fin number and size on the solidification output of a double-tube container filled with phase change material (PCM). By changing the dimensions of the fins, the heat transfer performance of PCM was examined and compared to scenarios without fins. Multiple inline configurations were explored to achieve optimal performance. The initial conditions of the heat transfer fluid (HTF) were considered in the analysis. The results showed that longer fins with higher numbers significantly improved the solidification rate of PCM.
ENERGY SCIENCE & ENGINEERING
(2023)
Article
Energy & Fuels
Husam Abdulrasool Hasan, Hussein Togun, Azher M. Abed, Nirmalendu Biswas, Hayder I. Mohammed
Summary: Modern society relies on energy storage systems such as Lithium-ion (Li-ion) batteries, which are sensitive to temperature changes. This study aims to improve the performance of Li-ion batteries by reducing operational temperatures through a novel design of an efficient air-cooling system. The results indicate that increasing air inlet velocity significantly reduces the average air temperature and temperature difference of the battery cells, while the average heat transfer rate of the cooling pack increases monotonically.
Article
Engineering, Multidisciplinary
Nidhal Ben Khedher, Hussein Togun, Azher M. M. Abed, Hayder I. I. Mohammed, Jasim M. M. Mahdi, Raed Khalid Ibrahem, Wahiba Yaici, Pouyan Talebizadehsardari, Amir Keshmiri
Summary: This study aims to investigate the impact of circular Y-shaped fins on a two-pipe latent heat-saving unit compared with conventional circular fins, in order to overcome the weak thermal conduction of phase change materials (PCM). The system is placed in a straight-up orientation, with the PCM located in the annulus and hot water used to charge the PCM. Various geometric factors of the fins, such as stem length, angle of the tributaries, and number of Y-shaped fins, are analyzed. The sensitivity analysis evaluates the influence of Reynolds number and temperature of the working fluid on the melting time and rate, with results showing that increasing fin height and number, and reducing tributary angles lead to improved system performance. Increasing Reynolds number and raising working fluid temperature also result in significant reductions in melting time.
ENGINEERING APPLICATIONS OF COMPUTATIONAL FLUID MECHANICS
(2023)
Article
Thermodynamics
Husam Abdulrasool Hasan, Hussein Togun, Azher M. Abed, Hayder Mohammed, Nirmalendu Biswas
Summary: The temperature management of Li-ion battery cell operations is crucial for its cycle life and performance. This study investigates the effects of a novel air-cooling system on the performance of lithium-ion batteries by reducing their operating temperatures. The findings demonstrate that increasing the spacing between the batteries can improve the thermal performance.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2023)
Article
Thermodynamics
Hussein Togun, Hakim S. Sultan, S. Hamidatou, Hayder Mohammed, Raad Z. Homod, Muataz S. Alhassan, Jameel M. Dhabab, Abdellatif M. Sadeq, Zaher Mundher Yaseen, K. Deghoum, A. Hadjad
Summary: This research numerically analyses the thermal improvement of nanofluid flow in forward-facing reduction channels with and without hybrid ribs. The study shows that triangular ribs have a significant influence on the system's thermal efficiency, with an increase in Nusselt number near the top of the rib before decreasing towards the heating surface. The Nusselt number increases from 5400 to 5600 as the concentration of nanofluids increases from 1 vol% to 4 vol%. Overall, the flow rate, nanofluid concentration, unit configuration, and ribs strongly affect the Nusselt number behavior and the unit's thermal performance.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2023)
Article
Construction & Building Technology
Nidhal Ben Khedher, Hussein Togun, Azher M. Abed, Hussein M. Taqi Al-Najjar, Anmar Dulaimi, Hayder I. Mohammed, Jasim M. Mahdi, A. Yvaz, Pouyan Talebizadehsardari
Summary: This study investigates the effect of circular Y-shaped fin arrangement on the low thermal response rates of a heat exchanger with Paraffin phase change material. Computational fluid dynamic simulations are conducted using ANSYS software, considering fluid flow, heat transfer, and phase change process. The optimal fin configuration is determined through sensitivity analysis of the Y-shaped fin's geometrical parameters. Results show that using Y-shaped fins reduces solidification time by 22% and enhances discharging rate by 26% compared to straight fins. The length of the fins is inversely proportional to solidification time, and increasing the number of fins improves heat transfer rate significantly.
JOURNAL OF BUILDING ENGINEERING
(2023)
Article
Thermodynamics
Husam Abdulrasool Hasan, Hussein Togun, Azher M. Abed, Naef A. A. Qasem, Aissa Abderrahmane, Kamel Guedri, Sayed M. Eldin
Summary: Temperature has a significant impact on the efficiency, security, and cycle life of lithium-ion battery cells. A new cooling system with a specific fluid velocity range is used to reduce the temperature of the cells. The results show that higher fluid velocity leads to better heat transfer. Among the investigated nanofluids, SiO2 exhibits the best thermal cooling for battery packs.
CASE STUDIES IN THERMAL ENGINEERING
(2023)
Article
Energy & Fuels
Raad Z. Homod, Ghazwan Noori Saad Jreou, Hayder Ibrahim Mohammed, Amjad Almusaed, Ahmed Kadhim Hussein, Wael Al-Kouz, Hussein Togun, Muneer A. Ismael, Hussein Alawai Ibrahim Al-Saaidi, Omer A. Alawi, Zaher Mundher Yaseen
Summary: Due to the influence of nonlinearities and high delay time, a hybrid model combining white-box and black-box approaches is developed to handle the behavior of a complex oil field system in Iraq. This model effectively represents the large data sets and achieves optimal fitness to measured values. The conversion of fuzzy rules into a multilayer perceptron network and the use of clustering technique and Gauss-Newton regression enhance the predictive performance of the hybrid model.
GEOENERGY SCIENCE AND ENGINEERING
(2023)
Article
Energy & Fuels
Raad Z. Homod, Basil Sh. Munahi, Hayder Ibrahim Mohammed, Musatafa Abbas Abbood Albadr, Aissa Abderrahmane, Jasim M. Mahdi, Mohamed Bechir Ben Hamida, Bilal Naji Alhasnawi, A. S. Albahri, Hussein Togun, Umar F. Alqsair, Zaher Mundher Yaseen
Summary: In this study, the control problem of the multiple-boiler system (MBS) is formulated as a dynamic Markov decision process and a deep clustering reinforcement learning approach is applied to obtain the optimal control policy. The proposed strategy, based on bang-bang action, shows superior response and achieves more than 32% energy saving compared to conventional fixed parameter controllers under dynamic indoor/outdoor actual conditions.
