Implicit Large Eddy Simulation of Low Pressure Turbine Airfoils Using a High Order Navier-Stokes Solver

2019 ◽  
Author(s):  
Marc Bolinches-Gisbert ◽  
Roque Corral ◽  
Fernando Gisbert ◽  
Adrián Sotillo

Author(s):  
C. L. Memory ◽  
J. P. Chen ◽  
J. P. Bons

Time-accurate numerical simulations were conducted on the aft-loaded L1A low pressure turbine airfoil at a Reynolds number of 22,000 (based on inlet velocity magnitude and axial chord length). This flow condition produces a non-reattaching laminar separation zone on the airfoil suction surface. The numerical code TURBO is used to simulate this flow field as an Implicit Large Eddy Simulation. Generally good agreement was found when compared to experimental time-averaged and instantaneous flow measurements. The numerical separation zone is slightly larger than that in the experiments, though integrated wake loss values improved from RANS-based simulations. Instantaneous snapshots of the numerical flow field showed the Kelvin Helmholtz instability forming in the separated shear layer and a large-scale vortex shedding pattern at the airfoil trailing edge. These features were observed in the experiments with similar sizes and vorticity levels. Power spectral density analyses revealed a global passage oscillation in the numerics that was not observed experimentally. This oscillation was most likely a primary resonant frequency of the numerical domain.



2016 ◽  
Vol 138 (7) ◽  
Author(s):  
C. L. Memory ◽  
J. P. Chen ◽  
J. P. Bons

Time-accurate numerical simulations were conducted on the aft-loaded L1A low-pressure turbine airfoil at a Reynolds number of 22,000 (based on inlet velocity magnitude and axial chord length). This flow condition produces a nonreattaching laminar separation zone on the airfoil suction surface. The numerical code TURBO is used to simulate this flow field as an implicit large eddy simulation (ILES). Generally, good agreement was found when compared to experimental time-averaged and instantaneous flow measurements. The numerical separation zone is slightly larger than that in the experiments, though integrated wake loss values improved from Reynolds-averaged Navier–Stokes (RANS)-based simulations. Instantaneous snapshots of the numerical flow field showed the Kelvin Helmholtz instability forming in the separated shear layer and a large-scale vortex shedding pattern at the airfoil trailing edge. These features were observed in the experiments with similar sizes and vorticity levels. Power spectral density analyses revealed a global passage oscillation in the numerics that was not observed experimentally. This oscillation was most likely a primary resonant frequency of the numerical domain.





Author(s):  
Fernando F. Grinstein

Abstract Accurate predictions with quantifiable uncertainties are essential to many practical turbulent flow applications exhibiting extreme geometrical complexity and broad ranges of length and time scales. Under-resolved computer simulations are typically unavoidable in such applications, and implicit large-eddy simulation (ILES) often becomes the effective strategy. We focus on ILES initialized with well-characterized 2563 homogeneous isotropic turbulence datasets generated with direct numerical simulation (DNS). ILES is based on the LANL xRAGE code, and solutions are examined as function of resolution for 643, 1283, 2563, and 5123 grids. The ILES performance of new directionally-unsplit high-order numerical hydrodynamics algorithms in xRAGE is examined. Compared to the initial 2563 DNS, we find longer inertial subranges and higher turbulence Re for directional-split 2563 & 5123 xRAGE — attributed to having linked DNS (Navier-Stokes based) solutions to nominally inviscid (higher Re) Euler based ILES solutions. Alternatively — for fixed resolution, we find that significantly higher simulated turbulence Re can be achieved with unsplit (vs. split) discretizations.



Author(s):  
Yoshinori Ooba ◽  
Hidekazu Kodama ◽  
Chuichi Arakawa ◽  
Yuichi Matsuo ◽  
Hitoshi Fujiwara ◽  
...  


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