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Application of vortex generators to Remove Heat Trapped in Closed Channels

Fluid Dynamics & Materials Processing 2023年第1期19卷 15-24页

作者： Alim Al Ayub Ahmed Salim Oudah Mezan Binyamin Murtadha Doghiam Abdullah Elena Tesleva Linar G.Akhmetov Rustem Zalilov Mustafa M.Kadhim Abduladheem Turki Jalil School of Accounting Jiujiang UniversityJiujiang332000China General Directorate of Education in Al-Muthanna Governorate Ministry of EducationSamawah66001Iraq Department of Mechanical Engineering Faculty of Science and TechnologyUniversitas Muhammadiyah Kalimantan TimurSamarinda75124Indonesia College of Petroleum Engineering Al-Ayen UniversityThi-Qar64001Iraq National Research Tomsk Polytechnic University Tomsk634050Russia Kazan Federal University Kazan420008Russian Nosov Magnitogorsk State Technical University Magnitogorsk455000Russia Department of Dentistry Kut University CollegeKutWasit52001Iraq College of Technical Engineering The Islamic UniversityNajaf7003Iraq Department of Pharmacy OsolAldeen University CollegeBaghdad993P+PWXIraq Faculty of Biology and Ecology Yanka Kupala State University of GrodnoGrodno230023Belarus

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 drop,it strongly contributes to increase the heat transfer coefficient inside the duct(up to 80–90%).

关键词： vortex generators heat trapped temperature of hot surfaces heat transfer

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Experimental investigation of flow and distortion mitigation by mechanical vortex generators in a coupled serpentine inlet-turbofan engine system

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Chinese Journal of Aeronautics 2020年第5期33卷 1375-1391页

作者： Iman MAGHSOUDI Mohammad Ali VAZIRY Mostafa MAHMOODI Department of Aerospace Malek-Ashtar University of TechnologyTehran 158751774Iran Department of Aerospace Malek-Ashtar University of TechnologyIsfahanShahinshahr 115/83145Iran

The performance of compact,aggressive ducts in advanced propulsion systems is limited by the internal flow separation coupled with the formation of secondary counter-rotating vortices that give rise to intensive flow distortions at the duct exit.An experimental investigation was conducted to study the flow field and passive suppression of flow separation and Aerodynamic Interface Plane (AIP) distortion in a serpentine air inlet duct.Tests were performed by a turbofan engine at several Engine Operating Points (EOPs) from 56%(idle) to 100%(max).A large total pressure deficit region arose at the upper part of the AIP,which was associated with the upper surface flow separation.Using the new mechanical S-type vortex generators in two longitudinal positions (VGl and VG2),separation and loss were diminished at the upper part of the duct and AIP.The VG2 arrangement attained the maximum reductions in distortion coefficients which were 73.72%,60.7% and 37.8% in DC(90°),DC(60°) and△P_C/P metrics,respectively.In the next step of the study,some unsteady aspects of the flow field were analyzed inside the duct.The separation onset and reattachment points were determined by the standard deviation of static pressure on the upper surface.The AIP spectral distribution showed that the boundary of low pressure and high pressure recovery regions was dominated by the maximum fluctuations.Furthermore,the PSD diagram of several probes at AIP revealed the vortex shedding frequency and its higher harmonics at separation region.The energy content of distinct unsteady spectral features in the bare configuration was significantly reduced using VGs,which showed the improvement of flow at the duct exit.

关键词： Distortion coefficient Power spectral density Serpentine inlet Total pressure vortex generators

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Simulating the Turbulent Hydrothermal Behavior of Oil/MWCNT Nanofluid in a Solar Channel Heat Exchanger Equipped with vortex generators

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Computer Modeling in Engineering & Sciences 2021年第3期126卷 855-889页

作者： Rachid Maouedj Younes Menni Mustafa Inc Yu-Ming Chu Houari Ameur Giulio Lorenzini Unite de Recherche en Energies Renouvelables en Milieu Saharien URERMSCentre de Developpement des Energies RenouvelablesCDERAdrar01000Algeria Department of Physics Unit of Research on Materials and Renewable EnergiesFaculty of SciencesAbou Bekr Belkaid UniversityTlemcen13000Algeria Department of Mathematics Science FacultyFirat UniversityElazig23119Turkey Department of Medical Research China Medical University HospitalChina Medical UniversityTaichung40402Taiwan Department of Mathematics Huzhou UniversityHuzhou313000China Hunan Provincial Key Laboratory of Mathematical Modeling and Analysis in Engineering Changsha University of Science&TechnologyChangsha410114China Department of Technology University Centre of NaamaNaama45000Algeria Department of Engineering and Architecture University of ParmaParco Area delle Scienze 181/AParma43124Italy

Re-engineering the channel heat exchangers(CHEs)is the goal of many recent studies,due to their great importance in the scope of energy transport in various industrial and environmental fields.Changing the internal geometry of the CHEs by using extended surfaces,i.e.,VGs(vortex generators),is the most common technique to enhance the efficiency of heat exchangers.This work aims to develop a newdesign of solar collectors to improve the overall energy efficiency.The study presents a new channel design by introducing VGs.The FVM(finite volume method)was adopted as a numerical technique to solve the problem,with the use of Oil/MWCNT(oil/multi-walled carbon nano-tubes)nanofluid to raise the thermal conductivity of the flow field.The study is achieved for a Re number ranging from12×10^(3) to 27×10^(3),while the concentration(φ)of solid particles in the fluid(Oil)is set to 4%.The computational results showed that the hydrothermal characteristics depend strongly on the flow patterns with the presence of VGs within the CHE.Increasing the Oil/MWCNT rates with the presence of VGs generates negative turbulent velocities with high amounts,which promotes the good agitation of nanofluid particles,resulting in enhanced great transfer rates.

关键词： Channel heat exchanger forced-convection Oil/MWCNT nanofluid CFD vortex generators

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CFD-Based Simulation and Analysis of Hydrothermal Aspects in Solar Channel Heat Exchangers with Various Designed vortex generators

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Computer Modeling in Engineering & Sciences 2021年第1期126卷 147-173页

作者： Mohamed Salmi Younes Menni Ali J.Chamkha HouariAmeur Rachid Maouedj Ahmed Youcef Department of Physics University of M’silaM’sila28000Algeria Laboratory of Physics and Chemistry of Materials University of M’silaM’sila28000Algeria Unit of Research on Materials and Renewable Energies Department of PhysicsAbou Bekr Belkaid UniversityTlemcen13000Algeria Faculty of Engineering Kuwait College of Science and TechnologyDoha DistrictKuwait Center of Excellence in Desalination Technology King Abdulaziz UniversityJeddah21589Saudi Arabia Department of Technology University Center of NaamaNaama45000Algeria Unite de Recherche en Energies Renouvelables en Milieu Saharien URERMSCentre de Developpement des Energies RenouvelablesCDERAdrar01000Algeria

The hydrothermal behavior of air inside a solar channel heat exchanger equipped with various shaped ribs is analyzed numerically.The bottom wall of the exchanger is kept adiabatic,while a constant value of the temperature is set at the upper wall.The duct is equipped with a flat rectangular fin on the upper wall and an upstream V-shaped baffle on the lower wall.Furthermore,five hot wall-attached rib shapes are considered:trapezoidal,square,triangular pointing upstream(type Ⅰ),triangular pointing downstream(type Ⅱ),and equilateral-triangular(type Ⅲ)cross sections.Effects of the flow rates are also inspected for various Reynolds numbers in the turbulent regime(1.2×10^(4)-3.2×10^(4)).The highest performance(η)value is given for the Ⅱ-triangular rib case in all Re values,while the square-shaped ribs show a significant decrease in the η along the achieved Re range.The η value at Remax is 2.567 for the Ⅱ-triangular roughness case.Compared with the other simulated cases,this performance is decreased by about 3.768%in the case of Ⅰ-triangular ribs,15.249% in the case of Ⅲ-triangular ribs,20.802% in the case of trapezoidal ribs,while 27.541% in the case of square ribs,at the same Remax.Also,a comparison ismade with air-heat exchangers that have non-rough walls and contain cross-shaped VGs presented previously,in order to highlight the effectiveness of the rough surface presence in the baffled and finned channels.The obtained results indicated that the triangular-shaped rib(type Ⅱ)has the most significant hydrothermal behavior than the other cases.This indicates the necessity of roughness heat transfer surfaces for finned and baffled channels to improve significantly the performance of the air-heat exchangers they contain.

关键词： CFD heat exchanger vortex generators ribs hydrothermal aspects

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