Numerical study comparing RANS and LES approaches on a circulation control airfoil

► RANS compared with LES for circulation control airfoil. ► RANS turbulence models need to account for streamline curvature. ► RANS models yield higher lift than LES in spite of predicting similar jet separation. A numerical study over a nominally two-dimensional circulation control airfoil is perfo...

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Bibliographic Details
Published in:The International journal of heat and fluid flow 2011-10, Vol.32 (5), p.847-864
Main Authors: Rumsey, Christopher L., Nishino, Takafumi
Format: Article
Language:English
Subjects:
Aerodynamics
Applied fluid mechanics
Circulation control
Curvature
Exact sciences and technology
Flow control
Fluid dynamics
Fundamental areas of phenomenology (including applications)
Large eddy simulation
Mathematical analysis
Mathematical models
Navier-Stokes equations
Physics
Position (location)
Separation
Turbulence
Turbulent flow
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Summary:► RANS compared with LES for circulation control airfoil. ► RANS turbulence models need to account for streamline curvature. ► RANS models yield higher lift than LES in spite of predicting similar jet separation. A numerical study over a nominally two-dimensional circulation control airfoil is performed using a large-eddy simulation code and two Reynolds-averaged Navier–Stokes codes. Different Coanda jet blowing conditions are investigated. In addition to investigating the influence of grid density, a comparison is made between incompressible and compressible flow solvers. The incompressible equations are found to yield negligible differences from the compressible equations up to at least a jet exit Mach number of 0.64. The effects of different turbulence models are also studied. Models that do not account for streamline curvature effects tend to predict jet separation from the Coanda surface too late, and can produce non-physical solutions at high blowing rates. Three different turbulence models that account for streamline curvature are compared with each other and with large eddy simulation solutions. All three models are found to predict the Coanda jet separation location reasonably well, but one of the models predicts specific flow field details near the Coanda surface prior to separation much better than the other two. All Reynolds-averaged Navier–Stokes computations produce higher circulation than large eddy simulation computations, with different stagnation point location and greater flow acceleration around the nose onto the upper surface. The precise reasons for the higher circulation are not clear, although it is not solely a function of predicting the jet separation location correctly.
ISSN:0142-727X
1879-2278
DOI:10.1016/j.ijheatfluidflow.2011.06.011