Unified approach for conjugate heat-transfer analysis of high speed air flow through a water-cooled nozzle

2016 ◽  
Vol 120 (1224) ◽  
pp. 355-373
Author(s):  
F. I. Barbosa ◽  
E. L. Zaparoli ◽  
C. R. Andrade
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
High Speed ◽  
Conjugate Heat Transfer ◽  
Cold Water ◽  
Transfer Problem ◽  
Air Flow ◽  
Heat Transfer Analysis ◽  
Bulk Temperature ◽  
Unified Approach

ABSTRACTThis article presents a unified approach to solve steady-state conjugate heat-transfer problem including simultaneously gas, liquid and solid regions in just one 3D domain, distinguished by their particular properties. This approach reduces approximation errors and the time to solve the problem, which characterise iterative methods based on separated domains. The formulation employs RANS equations, realisablek-ε turbulence model and near-wall treatment model. A commercial CFD code solves the pressure-based segregated algorithm combined with spatial discretisation of second order upwind. The problem consists of a convergent-divergent metallic nozzle that contains cooling channels divided in two segments along the wall. The nozzle wall insulates the high-speed hot air flow, dealt as perfect gas, from the two low-speed cold water flows, dealt as compressed liquid, both influenced by transport properties dependent of the local temperature. The verification process uses three meshes with increasing resolutions to demonstrate the independence of the results. The validation process compares the simulation results with experimental data obtained in high-enthalpy wind tunnel, demonstrating good compliance between them. Results for the bulk temperature rise of the water in the second cooling segment of the nozzle showed good agreement with available experimental data. Numerical simulations also provided wall temperature and heat flux for the gas and liquid sides. Besides, distribution of temperature, pressure, density and Mach number were plotted along the nozzle centerline showing a little disturbance downstream the throat. This phenomenon has been better visualised by means of 2D maps of those variables. The analysis of results indicates that the unified approach herein presented can make easier the task of simulating the conjugate convection-conduction heat-transfer in a class of problems related to regeneratively cooled thrust chambers.

Comparison of Conjugate Heat Transfer Analysis of Flat Plate Film Cooling Arrays Against Experimental Data

2015 ◽  
Author(s):  
William Humber ◽  
Ron-Ho Ni ◽  
Jamie Johnson ◽  
John Clark ◽  
Paul King
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Film Cooling ◽  
Conjugate Heat Transfer ◽  
Flow Characteristics ◽  
Heat Transfer Analysis ◽  
Pressure Side ◽  
Flat Plates ◽  
Cooling Effectiveness ◽  
Cooling Hole

Conjugate heat transfer (CHT) simulations were conducted for five film-cooled flat plates designed to model the pressure side of the High Impact Technologies Research Turbine First Vane (HIT RT1V). The numerical results of the CHT analysis were compared against experimental data. The five test cases consist of one baseline geometry and four different cooling hole geometries applied to a film-cooling hole arrangement that was optimized to achieve a more uniform cooling effectiveness. This optimized film-cooling hole configuration was designed by coupling a genetic algorithm with a Navier-Stokes fluid solver, using source terms to model film holes, starting from a baseline cooling configuration. All five plates were manufactured, and surface temperature measurements were taken using infrared thermography while the plates were exposed to flow conditions similar to the pressure side of the HIT RT1V. CHT simulations were carried out using unstructured meshes for both fluid and solid with all film holes fully resolved. Comparison of experimental data and simulations shows a consistent trend between the optimized configurations as well as correct predictions of the flow characteristics of each hole geometry although the absolute temperatures are underpredicted by the CHT. Both experimental measurements and CHT predictions show the optimized geometry with mini-trenched-shaped holes to give the best cooling effectiveness.

Conjugate heat transfer analysis of a radially cooled nozzle guide vane in an aero gas turbine engine

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
G. L. Arunkumar ◽  
Balachandra P. Shetty ◽  
R. K. Mishra
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Conjugate Heat Transfer ◽  
Guide Vane ◽  
Three Dimensional ◽  
Computational Method ◽  
Heat Transfer Analysis ◽  
Turbine Engine ◽  
Barrier Coating ◽  
Nozzle Guide

Abstract This paper presents a computational method to investigate cooling performance of NASA-C3X cascade vane coated with thermal barrier coating (TBC), for which experimental data are available. The vane was cooled internally by air flows through radially oriented 10 channels. A three-dimensional conjugate heat transfer simulation has been performed which allows the conduction-convection on metal vane by eliminating need of multiple boundary solutions. The predicted aerodynamic and thermal loads with the effect of turbulent intensity is found to be good agreement with experimental data and inclusion of TBC leads to quantitative reduction in vane metal temperature.

Conjugate heat transfer analysis of a radially cooled nozzle guide vane in an aero gas turbine engine

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
G. L. Arunkumar ◽  
Balachandra P. Shetty ◽  
R. K. Mishra
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Conjugate Heat Transfer ◽  
Guide Vane ◽  
Three Dimensional ◽  
Computational Method ◽  
Heat Transfer Analysis ◽  
Turbine Engine ◽  
Barrier Coating ◽  
Nozzle Guide

AbstractThis paper presents a computational method to investigate cooling performance of NASA-C3X cascade vane coated with thermal barrier coating (TBC), for which experimental data are available. The vane was cooled internally by air flows through radially oriented 10 channels. A three-dimensional conjugate heat transfer simulation has been performed which allows the conduction-convection on metal vane by eliminating need of multiple boundary solutions. The predicted aerodynamic and thermal loads with the effect of turbulent intensity is found to be good agreement with experimental data and inclusion of TBC leads to quantitative reduction in vane metal temperature.

scholarly journals Fully Coupled Large Eddy Simulation of Conjugate Heat Transfer in a Ribbed Channel with a 0.1 Blockage Ratio

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2096
Author(s):  
Joon Ahn ◽  
Jeong Chul Song ◽  
Joon Sik Lee
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Conjugate Heat Transfer ◽  
Heat Transfer Analysis ◽  
Scale Model ◽  
Computational Domain ◽  
Blockage Ratio ◽  
Ribbed Channel ◽  
Large Eddy ◽  
Cooling Passage

Large eddy simulations are performed to analyze the conjugate heat transfer of turbulent flow in a ribbed channel with a heat-conducting solid wall. An immersed boundary method (IBM) is used to determine the effect of heat transfer in the solid region on that in the fluid region in a unitary computational domain. To satisfy the continuity of the heat flux at the solid–fluid interface, effective conductivity is introduced. By applying the IBM, it is possible to fully couple the convection on the fluid side and the conduction inside the solid and use a dynamic subgrid scale model in a Cartesian grid. The blockage ratio (e/H) is set at 0.1, which is typical for gas turbine blades. Through conjugate heat transfer analysis, it is confirmed that the heat transfer peak in front of the rib occurs because of the impinging of the reattached flow and not the influence of the thermal boundary condition. When the rib turbulator acts as a fin, its efficiency and effectiveness are predicted to be 98.9% and 8.32, respectively. When considering conjugate heat transfer, the total heat transfer rate is reduced by 3% compared with that of the isothermal wall. The typical Biot number at the internal cooling passage of a gas turbine is <0.1, and the use of the rib height as the characteristic length better represents the heat transfer of the rib.

Experimental investigation of wall heat transfer due to spray combustion in a high-pressure/high-temperature vessel

2021 ◽  
pp. 146808742110072
Author(s):  
Karri Keskinen ◽  
Walter Vera-Tudela ◽  
Yuri M Wright ◽  
Konstantinos Boulouchos
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
High Pressure ◽  
High Temperature ◽  
High Speed ◽  
Transfer Problem ◽  
Wall Heat Transfer ◽  
Gas Temperature ◽  
Reference Case ◽  
High Pressure High Temperature

Combustion chamber wall heat transfer is a major contributor to efficiency losses in diesel engines. In this context, thermal swing materials (adapting to the surrounding gas temperature) have been pinpointed as a promising mitigative solution. In this study, experiments are carried out in a high-pressure/high-temperature vessel to (a) characterise the wall heat transfer process ensuing from wall impingement of a combusting fuel spray, and (b) evaluate insulative improvements provided by a coating that promotes thermal swing. The baseline experimental condition resembles that of Spray A from the Engine Combustion Network, while additional variations are generated by modifying the ambient temperature as well as the injection pressure and duration. Wall heat transfer and wall temperature measurements are time-resolved and accompanied by concurrent high-speed imaging of natural luminosity. An investigation with an uncoated wall is carried out with several sensor locations around the stagnation point, elucidating sensor-to-sensor variability and setup symmetry. Surface heat flux follows three phases: (i) an initial peak, (ii) a slightly lower plateau dependent on the injection duration, and (iii) a slow decline. In addition to the uncoated reference case, the investigation involves a coating made of porous zirconia, an established thermal swing material. With a coated setup, the projection of surface quantities (heat flux and temperature) from the immersed measurement location requires additional numerical analysis of conjugate heat transfer. Starting from the traces measured beneath the coating, the surface quantities are obtained by solving a one-dimensional inverse heat transfer problem. The present measurements are complemented by CFD simulations supplemented with recent rough-wall models. The surface roughness of the coated specimen is indicated to have a significant impact on the wall heat flux, offsetting the expected benefit from the thermal swing material.

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