Topical Collection "Cooling/Heat Transfer"
A topical collection in Aerospace (ISSN 2226-4310).
Dr. Qiang Zhang
School of Mathematics, Computer Science & Engineering, Department of Mechanical Engineering & Aeronautics, City, University of London, Northampton Square, London EC1V 0HB, UK
Interests: gas turbine heat transfer and cooling; aerodynamics; conjugate heat transfer; experimental techniques; CFD simulation and validation
Topical Collection Information
Our understanding on cooling and heat transfer technology have been continuously improved during the decades. With the development of advanced measurement techniques, experimental research is facing new opportunities and challenges on improving accuracy and resolution, enhancing accessibility, boundary condition control, and proper lab scaling method, etc. With the increasing computing power, CFD research now is dealing with new challenges in developing more efficient methods, resolving multiscale problems, unsteady phenomenon, and fluid-solid conjugation issues. Meanwhile, further improvements and new thermal management technologies may become more feasible with the recent developments in materials, manufacturing technology, systems integration and controls. It is a great pleasure to collect and share our understandings on the rich physics behind heat transfer mechanism, and new methods and ideas to embrace these opportunities and challenges.
The Special Issue welcoming papers on:
(i) Update of fundamental heat transfer theory
(ii) New internal & external cooling design concepts
(iii) Experimental methods & uncertainty improvement
(iv) High fidelity CFD in cooling / heat transfer
(v) Conjugate heat transfer experiments & CFD validation
Dr. Qiang Zhang
Manuscript Submission Information
Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the collection website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.
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Published Papers (4 papers)
Modelling and Simulation of Transpiration Cooling Systems for Atmospheric Re-Entry
Aerothermodynamic heating is one of the primary challenges faced in progressing towards reliable hypersonic transportation. In the present study, the transpiration cooling method applied to the thermal protection system of re-entry vehicles is investigated. The complexity in analysing the incoming heat flux for
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Aerothermodynamic heating is one of the primary challenges faced in progressing towards reliable hypersonic transportation. In the present study, the transpiration cooling method applied to the thermal protection system of re-entry vehicles is investigated. The complexity in analysing the incoming heat flux for re-entry lies not only in the extreme conditions of the flow but also in the fact that the coolant flow through the porous medium needs to be treated appropriately. While the re-entering spacecraft passes through various flow regimes, the peak conditions are faced only near continuum regime. Focusing on these conditions, traditional computational fluid dynamics techniques are used to model transpiration cooling for re-entry vehicles. In the current work, the open source CFD framework OpenFOAM is used to couple two different solvers iteratively and then analyse the thermal response for flow speed conditions typical of re-entry vehicles. Independent computations are performed using the explicit, loosely coupled procedure for high speed argon flow over a 2D axi-symmetrical cylindrical vehicle. The results presented indicate distinct heat flux drop along the surface of the cylindrical vehicle as a function of parameters such as coolant pressure and wall temperature.
Conjugate Heat Transfer Characteristics in a Highly Thermally Loaded Film Cooling Configuration with TBC in Syngas
Future power equipment tends to take hydrogen or middle/low heat-value syngas as fuel for low emission. The heat transfer of a film-cooled turbine blade shall be influenced more by radiation. Its characteristic of conjugate heat transfer is studied experimentally and numerically in the
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Future power equipment tends to take hydrogen or middle/low heat-value syngas as fuel for low emission. The heat transfer of a film-cooled turbine blade shall be influenced more by radiation. Its characteristic of conjugate heat transfer is studied experimentally and numerically in the paper by considering radiation heat transfer, multicomposition gas, and thermal barrier coating (TBC). The Weighted Sum of Gray Gases Spectral Model and the Discrete Transfer Model are utilized to solve the radiative heat transfer in the multicomposition field, while validated against the experimental data for the studied cases. It is shown that the plate temperature increases significantly when considering the radiation and the temperature gradient of the film-cooled plate becomes less significant. It is also shown that increasing percentage of steam in gas composition results in increased temperature on the film-cooled plate. The normalized temperature of the film-cooled plate decreases about 0.02, as the total percentage of steam in hot gas increases 7%. As for the TBC effect, it can smooth out the temperature distribution and insulate the heat to a greater extent when the radiative heat transfer becomes significant.
High Reynold Number LES of a Rotating Two-Pass Ribbed Duct
Cited by 1
Cooling of gas turbine blades is critical to long term durability. Accurate prediction of blade metal temperature is a key component in the design of the cooling system. In this design space, spatial distribution of heat transfer coefficients plays a significant role. Large-Eddy
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Cooling of gas turbine blades is critical to long term durability. Accurate prediction of blade metal temperature is a key component in the design of the cooling system. In this design space, spatial distribution of heat transfer coefficients plays a significant role. Large-Eddy Simulation (LES) has been shown to be a robust method for predicting heat transfer. Because of the high computational cost of LES as Reynolds number (Re
) increases, most investigations have been performed at low Re
). In this paper, a two-pass duct with a 180° turn is simulated at Re
= 100,000 for a stationary and a rotating duct at Ro
= 0.2 and Bo
= 0.5. The predicted mean and turbulent statistics compare well with experiments in the highly turbulent flow. Rotation-induced secondary flows have a large effect on heat transfer in the first pass. In the second pass, high turbulence intensities exiting the bend dominate heat transfer. Turbulent intensities are highest with the inclusion of centrifugal buoyancy and increase heat transfer. Centrifugal buoyancy increases the duct averaged heat transfer by 10% over a stationary duct while also reducing friction by 10% due to centrifugal pumping.
Turbine Blade Tip External Cooling Technologies
Cited by 1
This article provides an overview of gas turbine blade tip external cooling technologies. It is not the intention to comprehensively review all the publications from past to present. Instead, selected reports, which represent the most recent progress in tip cooling technology in open
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This article provides an overview of gas turbine blade tip external cooling technologies. It is not the intention to comprehensively review all the publications from past to present. Instead, selected reports, which represent the most recent progress in tip cooling technology in open publications, are reviewed. The cooling performance on flat tip and squealer tip blades from reports are compared and discussed. As a generation conclusion, tip clearance dimension and coolant flow rate are found as the most important factors that significant influence the blade tip thermal performance was well as the over tip leakage (OTL) flow aerodynamics. However, some controversial trends are reported by different researchers, which could be attributed to various reasons. One of the causes of this disagreement between different reports is the lacking of unified parametric definition. Therefore, a more appropriate formula of blowing ratio definition has been proposed for comparison across different studies. The last part of the article is an outlook of the new techniques that are promising for future tip cooling research. As a new trend, the implementation of artificial intelligence techniques, such as genetic algorithm and neural network, have become more popular in tip cooling optimization, and they will bring significantly changes to the future turbine tip cooling development.
The below list represents only planned manuscripts. Some of these
manuscripts have not been received by the Editorial Office yet. Papers
submitted to MDPI journals are subject to peer-review.
- High speed rotor, Prof. Mike Dunn, Ohio State Unviersity
- Film cooling experimental research (LIF, PIV, IR, PSP), Prof. Ken Takeishi, Tokushima Bunri University
- Additive manufacturing & cooling research, Prof. Karen Thole, Pennsylvania State University
- Design of turbine experimental facilities in heat transfer, Prof. Guillermo Paniagua, Purdue University
- High temperature experimental rig, Prof. Jing Ren, Tsinghua University
- Heat transfer HTC scaling / Biot number, Prof. Tom Shih, Purdue University
- CFD- Multiscale modelling, Prof. Li He, Oxford University
- CFD- LES in Internal Cooling, Prof. Danish Tafti, Virginia Tech
- Unsteady thermal management - scan- cooling concept, Dr. Qiang Zhang, City, University of London