Computational Methodology for Large-Eddy Simulation of Tip-Clearance Flows

AIAA Journal ◽  
2004 ◽  
Vol 42 (2) ◽  
pp. 271-279 ◽  
Author(s):  
Donghyun You ◽  
Rajat Mittal ◽  
Meng Wang ◽  
Parviz Moin
Keyword(s):  
Large Eddy Simulation ◽  
Tip Clearance ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Computational Methodology

scholarly journals Verification and Validation of Large Eddy Simulation for Tip Clearance Vortex Cavitating Flow in a Waterjet Pump

Energies ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7635
Author(s):  
Chengzao Han ◽  
Yun Long ◽  
Mohan Xu ◽  
Bin Ji
Keyword(s):  
Large Eddy Simulation ◽  
Tip Clearance ◽  
Verification And Validation ◽  
Flow Structures ◽  
Tip Clearance Flow ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Clearance Flow ◽  
Vorticity Transport ◽  
Waterjet Pump

In this paper, large eddy simulation (LES) was adopted to simulate the cavitating flow in a waterjet pump with emphasis on the tip clearance flow. The numerical results agree well with the experimental observations, which indicates that the LES method can make good predictions of the unsteady cavitating flows around a rotor blade. The LES verification and validation (LES V&V) analysis was used to reveal the influence of cavitation on the flow structures. It can be found that the LES errors in cavitating region are larger than those in the non-cavitating area, which is mainly caused by more complicated cavitating and tip clearance flow structures. Further analysis of the interaction between the cavitating and vortex flow by the relative vorticity transport equation shows that the stretching, dilatation and baroclinic torque terms have major effects on the generation and transport of vortex structure. Meanwhile the Coriolis force term and viscosity term also exacerbate the vorticity transport in the cavitating region. In addition, the flow loss characteristics of this pump are also revealed by the entropy production theory. It is indicated that the tip clearance flow and trailing edge wake flow cause the viscous dissipation and turbulent dissipation, and the cavitation can further enhance the instability of the flow field in the tip clearance.

A Computational Methodology for Large-Eddy Simulation of Tip-Clearance Flows

2003 ◽  
Author(s):  
Donghyun You ◽  
Rajat Mittal ◽  
Meng Wang ◽  
Parviz Moin
Keyword(s):  
Large Eddy Simulation ◽  
Pressure Fluctuations ◽  
Spatial Dynamics ◽  
Quantitative Agreement ◽  
Tip Clearance ◽  
Immersed Boundary ◽  
Tip Clearance Flow ◽  
Mesh Topology ◽  
Eddy Simulation ◽  
Large Eddy

A large-eddy simulation (LES) solver which combines an immersed-boundary technique with a curvilinear structured grid has been developed to study the temporal and spatial dynamics of an incompressible rotor tip-clearance flow. The overall objective of these simulations is to determine the underlying mechanisms for low-pressure fluctuations downstream of the rotor near the endwall. Salient features of the numerical methodology, including the mesh topology, the immersed boundary method, the treatment of numerical instability for non-dissipative schemes on highly skewed meshes, and the parallelization of the code for shared memory platforms are discussed. The computational approach is shown to be capable of capturing the evolution of the highly complicated flowfield characterized by the interaction of distinct blade-associated vortical structures with the turbulent endwall boundary layer. Simulation results are compared with experiments and qualitative as well as quantitative agreement is observed.

Study of flow in tip-clearance turbomachines using large-eddy simulation

2004 ◽  
Vol 6 (6) ◽  
pp. 38-46 ◽  
Author(s):  
Donghyun You ◽  
Meng Wang ◽  
Rajat Mittal ◽  
P. Moin
Keyword(s):  
Large Eddy Simulation ◽  
Tip Clearance ◽  
Eddy Simulation ◽  
Large Eddy

scholarly journals Zonal Large-Eddy Simulation of a Fan Tip-Clearance Flow, With Evidence of Vortex Wandering

2015 ◽  
Vol 137 (6) ◽  
Author(s):  
Jérôme Boudet ◽  
Adrien Cahuzac ◽  
Philip Kausche ◽  
Marc C. Jacob
Keyword(s):  
Large Eddy Simulation ◽  
Good Description ◽  
Region Of Interest ◽  
Tip Clearance ◽  
Velocity Spectrum ◽  
Tip Leakage Flow ◽  
Tip Clearance Flow ◽  
Tip Leakage ◽  
Eddy Simulation ◽  
Large Eddy

The flow in a fan test-rig is studied with combined experimental and numerical methods, with a focus on the tip-leakage flow. A zonal RANS/LES approach is introduced for the simulation: the region of interest at tip is computed with full large-eddy simulation (LES), while Reynolds-averaged Navier–Stokes (RANS) is used at inner radii. Detailed comparisons with the experiment show that the simulation gives a good description of the flow. In the region of interest at tip, a remarkable prediction of the velocity spectrum is achieved, over about six decades of energy. The simulation precisely captures both the tonal and broadband contents. Furthermore, a detailed analysis of the simulation allows identifying a tip-leakage vortex (TLV) wandering, whose influence onto the spectrum is also observed in the experiment. This phenomenon might be due to excitation by upstream turbulence from the casing boundary layer and/or the adjacent TLV. It may be a precursor of rotating instability. Finally, considering the outlet duct acoustic spectrum, the vortex wandering appears to be a major contribution to noise radiation.

Analysis of Solid Particle Ingestion and Dynamics in a Turbomachine Using Large-Eddy Simulation

2019 ◽  
Author(s):  
Benjamin Martin ◽  
Martin Thomas ◽  
Jérôme Dombard ◽  
Florent Duchaine ◽  
Laurent Gicquel
Keyword(s):  
Large Eddy Simulation ◽  
Gas Turbine ◽  
Solid Particle ◽  
Turbine Blades ◽  
Operating Conditions ◽  
Tip Clearance ◽  
Lagrangian Formalism ◽  
Eddy Simulation ◽  
Wide Range ◽  
Large Eddy

Abstract Erosion of compressor and turbine blades operating in extreme environment fouled with sand particles, ash or soot is a serious problem for gas turbine manufacturers and users. Indeed, operation of a gas turbine engine in such hostile conditions leads to drastic degradation of the aerodynamic performance of the components, mostly through surface roughness modification, tip clearance height increase or blunting of blade leading edges. To evaluate associated risks, the computation of particle trajectories and impacts through multiple turbomachinery stages by Computational Fluid Dynamics (CFD) seems a decent path but remains a challenge. The numerical prediction of complex turbulent flows in compressors and turbines is however necessary in such a context and validations are still required. Recently, Large-Eddy Simulation (LES) has shown promising results for compressor and turbine configurations for a wide range of operating conditions at an acceptable cost. With this in mind, this article presents the assessment of a LES solver able to treat turbomachine configurations to predict solid particle motion. To do so, the governing equations of particle dynamics are introduced using the Lagrangian formalism and are solved to compute locations and conditions of impact, namely particle velocity, angle and radius. The fully unsteady and coupled strategy is applied to blade geometries for studying the main areas and conditions of impacts obtained with LES. For comparison, a one-way coupling computation based on a mean steady flow field where only the Lagrangian particles are advanced in time is performed to evaluate the gain and drawbacks of both methods.

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