Large eddy simulation of the effects of rotation on heat transfer in a ribbed channel

2002 ◽  
Author(s):  
Joon Sang Lee ◽  
Yang Liu ◽  
Richard H. Pletcher
Keyword(s):  
Heat Transfer ◽  
Large Eddy Simulation ◽  
Ribbed Channel ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Effects Of Rotation

Large-Eddy Simulation of the Flow Developing in Static and Rotating Ribbed Channels

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Florent Duchaine ◽  
Laurent Gicquel ◽  
Thomas Grosnickel ◽  
Charlie Koupper
Keyword(s):  
Heat Transfer ◽  
Large Eddy Simulation ◽  
Static Case ◽  
Experimental Database ◽  
Ribbed Channel ◽  
Eddy Simulation ◽  
Rotation Numbers ◽  
Large Eddy ◽  
Potential Impact ◽  
Transversal Pressure

Abstract In the present work, the turbulent flow fields in a static and rotating ribbed channel representative of an aeronautical gas turbine are investigated by the means of wall-resolved compressible large-Eddy simulation (LES). This approach has been previously validated in a squared ribbed channel based on an experimental database from the Von Karman Institute (Reynolds and rotation numbers of about 15,000 and ±0.38, respectively). LES results prove to reproduce differences induced by buoyancy in the near rib region and resulting from adiabatic or anisothermal flows under rotation. The model also manages to predict the turbulence increase (decrease) around the rib in destabilizing (stabilizing) rotation of the ribbed channels. On this basis, this paper investigates in more detail the spatial development of the flow along the channel and its potential impact on secondary flow structures. More specifically and for all simulations, results of the adiabatic static case exhibit two contra-rotating structures that are close to the lateral walls of the channel induced by transversal pressure difference created by the ribs. These structures are generated after the first ribs and appear behind all inter-rib sections, their relative position is partly affected by rotation. When considering the stabilizing rotating case, two additional contra-rotating structures also develop along the channel from the entrance close to the low-pressure wall (rib-mounted side). These vortices are due to the confinement of the configuration, inflow profile and are the result of Coriolis forces induced by rotation. Görtler vortices also appear on the pressure wall (opposite to the rib-mounted side). In the destabilizing rotating case, these two types of secondary structures are found to co-exist, and their migration in the channel is significantly different due to the presence of the ribs on the pressure side. Finally, it is shown that heat transfer affects only marginally the static and stabilized cases while it changes more significantly the flow organization in the destabilizing case mainly because of enhanced heat transfer and increased buoyancy force effects.

Large Eddy Simulation of the Flow Developing in Static and Rotating Ribbed Channels

2019 ◽  
Author(s):  
Florent Duchaine ◽  
Laurent Gicquel ◽  
Thomas Grosnickel ◽  
Charlie Koupper
Keyword(s):  
Heat Transfer ◽  
Large Eddy Simulation ◽  
Static Case ◽  
Experimental Database ◽  
Ribbed Channel ◽  
Eddy Simulation ◽  
Rotation Numbers ◽  
Large Eddy ◽  
Potential Impact ◽  
Transversal Pressure

Abstract In the present work, the turbulent flow fields in a static and rotating ribbed channel representative of an aeronautical gas turbine are investigated by mean of wall-resolved compressible Large Eddy Simulation (LES). This approach has been previously validated in a squared ribbed channel based on an experimental database from Von Karman Institute (Reynolds and rotation numbers of about 15000 and +/− 0.38 respectively). LES results prove to reproduce differences induced by buoyancy in the near rib region and resulting from adiabatic or anisothermal flows under rotation. The model also manages to predict the turbulence increase (decrease) around the rib in destabilizing (stabilizing) rotation of the ribbed channels. On this basis, this paper investigates in more details the spatial development of the flow along the channel and its potential impact on secondary flow structures. More specifically and for all simulations, results on the adiabatic static case exhibits two contra-rotating structures close to the lateral walls of the channel induced by transversal pressure difference created by the ribs. These structures are generated after the first ribs and appear behind all inter rib sections, their relative position being partly affected by rotation. When considering the stabilizing rotating case, two additional contra-rotating structures also develop along the channel from the entrance close to the low-pressure wall (rib-mounted side). These vortices are due to the confinement of the configuration, inflow profile and are the result of Coriolis forces induced by rotation. Görtler vortices also appear on the pressure wall (opposite to the rib-mounted side). In the destabilizing rotating case, these two types of secondary structures are found to co-exist and their migration in the channel is significantly different due to the presence of the ribs on the pressure side. Finally, it is shown that heat transfer affects only marginally the static and stabilized cases while it changes more significantly the flow organization in the destabilizing case mainly because of enhanced heat transfer and increased buoyancy force effects.

scholarly journals Assessing IDDES-Based Wall-Modeled Large-Eddy Simulation (WMLES) for Separated Flows with Heat Transfer

Fluids ◽  
2021 ◽  
Vol 6 (7) ◽  
pp. 246
Author(s):  
Rozie Zangeneh
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Large Eddy Simulation ◽  
Skin Friction ◽  
Heat Fluxes ◽  
Separated Flows ◽  
Detached Eddy Simulation ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Isothermal Wall

The Wall-modeled Large-eddy Simulation (WMLES) methods are commonly accompanied with an underprediction of the skin friction and a deviation of the velocity profile. The widely-used Improved Delayed Detached Eddy Simulation (IDDES) method is suggested to improve the prediction of the mean skin friction when it acts as WMLES, as claimed by the original authors. However, the model tested only on flow configurations with no heat transfer. This study takes a systematic approach to assess the performance of the IDDES model for separated flows with heat transfer. Separated flows on an isothermal wall and walls with mild and intense heat fluxes are considered. For the case of the wall with heat flux, the skin friction and Stanton number are underpredicted by the IDDES model however, the underprediction is less significant for the isothermal wall case. The simulations of the cases with intense wall heat transfer reveal an interesting dependence on the heat flux level supplied; as the heat flux increases, the IDDES model declines to predict the accurate skin friction.

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%.

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