Conjugate heat transfer study of hypersonic flow past a cylindrical leading edge composed of functionally graded materials

2021 ◽  
pp. 095440622110481
Author(s):  
Bibin John ◽  
Sudhanva Kusuma Chandrashekhara ◽  
Vivekkumar Panneerselvam
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Functionally Graded Materials ◽  
Isotropic Material ◽  
Conjugate Heat Transfer ◽  
Thermal Protection ◽  
Leading Edge ◽  
Functionally Graded ◽  
Graded Materials ◽  
Flow And Heat Transfer

Aero-thermodynamic analysis of a cylindrical leading edge placed in a hypersonic stream is carried out using an in-house developed conjugate heat transfer (CHT) solver. Isotropic and functionally graded materials (FGM) are tested as heat shields to understand the effects of the material property on the flow structure and aerodynamic heating associated with the mutual coupling of fluid flow and heat transfer. A simplified partitioned approach is employed to couple the independently developed fluid flow and heat transfer solvers to perform conjugate heat transfer studies. This framework employs a cell-centred finite volume formulation with an edge-based algorithm. Both strong and loose coupling algorithms are implemented for the data transfer across the fluid–solid interface. A test case of hypersonic flow over a cylindrical leading edge composed of an isotropic material is considered to validate the accuracy and correctness of numerical formulation adopted in the in-house solver. The significance of solid domain materials on the conjugate heat transfer has been studied by considering both isotropic material and FGM. The loosely coupled CHT solver required 10 times less simulation time when compared with the strongly coupled CHT solver. The interface heat flux evolution over time showed a decreasing trend, whereas an increasing trend was for the interface temperature. The current study strongly recommends CHT analysis for the design of thermal protection system of space vehicles. The thermal performance of FGMs composed of various volume fractions of Zirconia and Titanium alloy (Ti6Al4V) is assessed. The temperature distributions obtained from the CHT analysis shows that FGM with a power index of unity is a good material choice for thermal protection systems.

Self-propagating high-temperature synthesis of functionally graded materials as thermal protection systems for high-temperature applications

2003 ◽  
Vol 18 (2) ◽  
pp. 448-455 ◽  
Author(s):  
N. Bertolino ◽  
M. Monagheddu ◽  
A. Tacca ◽  
P. Giuliani ◽  
C. Zanotti ◽  
...  
Keyword(s):  
High Temperature ◽  
Functionally Graded Materials ◽  
Thermal Protection ◽  
Functionally Graded ◽  
Temperature Synthesis ◽  
Thermal Tests ◽  
Graded Materials ◽  
Thermal Barriers ◽  
High Temperature Synthesis ◽  
Spatial Composition

Self-propagating high-temperature synthesis was used to prepare boride-based functionally graded materials (FGMs) as thermal barriers for space re-entry vehicles. FGMs are characterized by inhomogeneous spatial composition, resulting in different spatial characteristics. In this work, the FGMs were composed of a ceramic [i.e., MB2 (M = Ti, Zr, Hf)] and a metallic (i.e., NiAl) side, joined together by composite layers of graded stoichiometries of the two components. Thus, in the same material, the boride end gives thermal insulation, while the intermetallic end offers an easy junction to the structure of the space aircraft. The prepared FGMs showed good adhesion between the layers and global compactness after preparation and thermal tests. The microhardness along the samples was measured, and their insulating capabilities were evaluated.

3-D Conjugate Flow and Heat Transfer Investigations of a Film-Cooled Turbine Guide Vane With Different Blowing Ratios

1997 ◽  
Author(s):  
Dieter E. Bohn ◽  
Tom Heuer ◽  
Karsten A. Kusterer
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Guide Vane ◽  
Leading Edge ◽  
Cooling Fluid ◽  
Hot Gas ◽  
Flow And Heat Transfer ◽  
Passage Vortex ◽  
Turbine Guide Vane ◽  
Conjugate Calculation

Film-cooling has become a widely used cooling method in present day gas turbines. Cooling gas ejection at the leading edge serves to protect the entire vane surface from contact with the hot gas. With doing this, material temperatures are reduced in order to guarantee an economically acceptable life span of the vane. This paper describes the application of a numerical method for the conjugate calculation of internal and external fluid flows and the heat transfer in and through the blade walls of a film-cooled turbine guide vane. The advantage of this approach is that it is possible to predict fluid flow properties and wall temperatures without the need for additional heat transfer conditions or temperature conditions at the external surfaces of the vane. This is a great advantage because the desired data are either unknown or not available for the calculation in the design process of new cooled blades or vanes. In a complete calculation of external and internal flows, no additional boundary conditions at the internal surfaces of the cooling geometry are needed either. Another advantage is the interaction of fluid flow and heat transfer which is taken into account by the conjugate calculation. In the 3-D numerical experiment to be presented, the influence of leading edge cooling fluid ejection on the temperature distribution in the vane material is investigated. The cooling fluid is ejected through two slots at the leading edge. The calculations are performed for three blowing ratios in order to investigate the efficiency of the cooling method. Realistic temperature ratios of cooling-fluid flow and main flow are considered. Such information is very useful in the aero thermal design process of new cooling configurations, since the amount of experimental work can be minimized. The results show the influence of complex 3-D flow phenomena (e.g. passage vortex) on the cooling fluid distribution on the vane surface as a function of the chosen blowing factor. Due to the influence of the passage vortex, the cooling fluid is displaced and leaves the vane surface near the side-wall uncovered against the hot gas. Furthermore, cooling fluid displacement on the pressure side according to the ejection slot geometry leads to another unprotected region on the vane surface. These effects have severe consequences on the thermal load of the vane and can reduce its life span.

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