scholarly journals High-Fidelity Multiphysics Simulation of a Confined Premixed Swirling Flame Combining Large-Eddy Simulation, Wall Heat Conduction and Radiative Energy Transfer

2017 ◽  
Author(s):  
Chai Koren ◽  
Ronan Vicquelin ◽  
Olivier Gicquel
Keyword(s):  
Heat Transfer ◽  
Heat Conduction ◽  
Large Eddy Simulation ◽  
Wall Temperature ◽  
Radiative Heat Transfer ◽  
Conjugate Heat Transfer ◽  
Radiative Heat ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Swirling Flame

A multi-physics simulation combining large-eddy simulation, conjugate heat transfer and radiative heat transfer is used to predict the wall temperature field of a confined premixed swirling flame operating under atmospheric pressure. The combustion model accounts for the effect of enthalpy defect on the flame structure whose stabilization is here sensitive to the wall heat losses. The conjugate heat transfer is accounted for by solving the heat conduction within the combustor walls and with the Hybrid-Cell Neumann-Dirichlet coupling method, enabling to dynamically adapt the coupling period. The exact radiative heat transfer equation is solved with an advanced Monte Carlo method with a local control of the statistical error. The coupled simulation is carried out with or without accounting for radiation. Excellent results for the wall temperature are achieved by the fully coupled simulation which are then further analyzed in terms of radiative effects, global energy budget and fluctuations of wall heat flux and temperature.

scholarly journals Large-Eddy Simulation Study of Flow and Heat Transfer in Swirling and Non-Swirling Impinging Jets on a Semi-Cylinder Concave Target

2021 ◽  
Vol 11 (15) ◽  
pp. 7167
Author(s):  
Liang Xu ◽  
Xu Zhao ◽  
Lei Xi ◽  
Yonghao Ma ◽  
Jianmin Gao ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Large Eddy Simulation ◽  
Wall Temperature ◽  
Target Surface ◽  
Impinging Jets ◽  
Small Scale ◽  
Complex Flow ◽  
Eddy Simulation ◽  
Flow And Heat Transfer ◽  
Large Eddy

Swirling impinging jet (SIJ) is considered as an effective means to achieve uniform cooling at high heat transfer rates, and the complex flow structure and its mechanism of enhancing heat transfer have attracted much attention in recent years. The large eddy simulation (LES) technique is employed to analyze the flow fields of swirling and non-swirling impinging jet emanating from a hole with four spiral and straight grooves, respectively, at a relatively high Reynolds number (Re) of 16,000 and a small jet spacing of H/D = 2 on a concave surface with uniform heat flux. Firstly, this work analyzes two different sub-grid stress models, and LES with the wall-adapting local eddy-viscosity model (WALEM) is established for accurately predicting flow and heat transfer performance of SIJ on a flat surface. The complex flow field structures, spectral characteristics, time-averaged flow characteristics and heat transfer on the target surface for the swirling and non-swirling impinging jets are compared in detail using the established method. The results show that small-scale recirculation vortices near the wall change the nearby flow into an unstable microwave state, resulting in small-scale fluctuation of the local Nusselt number (Nu) of the wall. There is a stable recirculation vortex at the stagnation point of the target surface, and the axial and radial fluctuating speeds are consistent with the fluctuating wall temperature. With the increase in the radial radius away from the stagnation point, the main frequency of the fluctuation of wall temperature coincides with the main frequency of the fluctuation of radial fluctuating velocity at x/D = 0.5. Compared with 0° straight hole, 45° spiral hole has a larger fluctuating speed because of speed deflection, resulting in a larger turbulence intensity and a stronger air transport capacity. The heat transfer intensity of the 45° spiral hole on the target surface is slightly improved within 5–10%.

Large Eddy Simulation of Conjugate Heat Transfer Around a Multi-Perforated Plate With Deviation

2016 ◽  
Author(s):  
Dorian Lahbib ◽  
Antoine Dauptain ◽  
Florent Duchaine ◽  
Franck Nicoud
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Large Eddy Simulation ◽  
Conjugate Heat Transfer ◽  
Pressure Ratio ◽  
Perforated Plate ◽  
Inlet Temperature ◽  
Plate Temperature ◽  
Eddy Simulation ◽  
Large Eddy

To improve gas turbine efficiency, engine manufacturers increase both the overall compressor pressure ratio and the turbine inlet temperature, resulting into a higher thermal load of the combustion chamber walls. Cooling systems such as multi-perforated plates are in this context good candidates to lower the thermal constraints on the liners. Such technological devices consist in introducing, through submillimetric holes, a cold air flow into the boundary layer of the chamber wall. Though commonly used in industrial applications, perforations with an angle of deviation, i.e. not aligned with the main flow, have not been studied in most experimental and numerical studies. The deviation angle impacts the liner temperature by modifying the flow structure around the plate. Conjugate heat transfer computations coupling Large Eddy Simulation and heat conduction are performed on streamwise and 45 angled configurations composed of 12 rows at an operating point representative of helicopter combustors to analyze the effect of the deviation. The flow organization around the plate is modified, yielding different heat flux distribution and plate temperature. The major differences are observed within the perforations where the heat flux coefficient increases up to 54% in the configuration with deviation.

scholarly journals Conjugate heat transfer with Large Eddy Simulation for gas turbine components

2009 ◽  
Vol 337 (6-7) ◽  
pp. 550-561 ◽  
Author(s):  
Florent Duchaine ◽  
Simon Mendez ◽  
Franck Nicoud ◽  
Alban Corpron ◽  
Vincent Moureau ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Large Eddy Simulation ◽  
Gas Turbine ◽  
Conjugate Heat Transfer ◽  
Eddy Simulation ◽  
Large Eddy
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