Numerical Investigation of 3-D Dynamic Stall using Delayed Detached Eddy Simulation

2012 ◽  
Author(s):  
Shivaji Medida ◽  
James Baeder
Keyword(s):  
Numerical Investigation ◽  
Dynamic Stall ◽  
Detached Eddy Simulation ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation

Simulation of Dynamic Stall on an Elastic Rotor in High-Speed Turn Flight

2020 ◽  
Vol 65 (2) ◽  
pp. 1-12
Author(s):  
Johannes Letzgus ◽  
Manuel Keßler ◽  
Ewald Krämer
Keyword(s):  
High Speed ◽  
Separated Flow ◽  
Flight Test ◽  
Dynamic Stall ◽  
Minor Role ◽  
Detached Eddy Simulation ◽  
Rotor Aerodynamics ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation ◽  
A Minor

A highly loaded, high-speed turn flight of Airbus Helicopters' Bluecopter demonstrator helicopter is simulated to investigate dynamic stall using a loose computational fluid dynamics/structural dynamics (CFD/CSD) coupling of the flow solver FLOWer and the rotorcraft comprehensive code CAMRAD II. The rotor aerodynamics is computed using a high-fidelity delayed detached-eddy simulation (DDES). A three-degree-of-freedom trim of an isolated rotor is performed, yielding main-rotor control angles that agree well with the flight-test measurements. The flow field in this flight condition is found to be highly unsteady and complex, featuring massively separated flow, blade–vortex interaction, multiple dynamic-stall events, and shock-induced separation. The computed pitch-link loads are compared to flight-test measurements. This shows that all CFD/CSD cases underpredict the amplitudes of the flight test and yield phase shifts. However, overall trends agree reasonably. Also, varying the computational setup reveals that the shear stress transport–DDES turbulence model performs better than Spalart–Allmaras–DDES, that the consideration of the rotor hub and fuselage improves the agreement with flight-test data, and that the elastic twist plays only a minor role in the dynamic-stall events.

scholarly journals Numerical Investigation of Powered Jet Effects by RANS/LES Hybrid Methods

2019 ◽  
Vol 37 (3) ◽  
pp. 565-571
Author(s):  
Zhibin Gong ◽  
Jie Li ◽  
Jixiang Shan ◽  
Heng Zhang
Keyword(s):  
Numerical Investigation ◽  
Hybrid Methods ◽  
Three Dimensional ◽  
Jet Flow ◽  
Weno Scheme ◽  
Detached Eddy Simulation ◽  
Turbulent Structures ◽  
Ambient Flow ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation

For the high-precision simulation of engine jet effects, an improved delayed detached eddy simulation (IDDES) method based on the two-equation shear stress transport (SST) model is developed, and the fifth-order finite-volume weighted essentially non-oscillatory (WENO) scheme is employed to enhance accuracy of spatial discretization, and then numerical investigation of powered jet effects by RANS/LES hybrid methods is carried out. The effects of the grid distributions and the accuracy of the spatial schemes are discussed during the RANS/LES validation analysis on the fully expanded jet flow and Acoustic Reference Nozzle (ARN) jet flow. The results show that, by enlarging the grid density and improving the accuracy of the spatial schemes, the velocity distributions in the jet flow can be better predicted, the non-physical steady flow after the jet nozzle can be shortened, the instantaneous flow structures are clearer and the turbulent intensities are more accurate. Then IDDES simulation of turbofan engine jet flow is carried out. The mixing characteristics of the external fan jet flow and internal core jet flow as well as the ambient flow are obtained, and the three-dimensional turbulent structures are also given.

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