Large Eddy Simulation and CDNS Investigation of T106C Low-Pressure Turbine

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Site Hu ◽  
Chao Zhou ◽  
Zhenhua Xia ◽  
Shiyi Chen
Keyword(s):  
Large Eddy Simulation ◽  
Flow Separation ◽  
Separated Flow ◽  
Low Pressure ◽  
Secondary Flows ◽  
Computational Domain ◽  
Suction Surface ◽  
Low Pressure Turbine ◽  
Eddy Simulation ◽  
Large Eddy

This study investigates the aerodynamic performance of a low-pressure turbine, namely the T106C, by large eddy simulation (LES) and coarse grid direct numerical simulation (CDNS) at a Reynolds number of 100,000. Existing experimental data were used to validate the computational fluid dynamics (CFD) tool. The effects of subgrid scale (SGS) models, mesh densities, computational domains and boundary conditions on the CFD predictions are studied. On the blade suction surface, a separation zone starts at a location of about 55% along the suction surface. The prediction of flow separation on the turbine blade is always found to be difficult and is one of the focuses of this work. The ability of Smagorinsky and wall-adapting local eddy viscosity (WALE) model in predicting the flow separation is compared. WALE model produces better predictions than the Smagorinsky model. CDNS produces very similar predictions to WALE model. With a finer mesh, the difference due to SGS models becomes smaller. The size of the computational domain is also important. At blade midspan, three-dimensional (3D) features of the separated flow have an effect on the downstream flows, especially for the area near the reattachment. By further considering the effects of endwall secondary flows, a better prediction of the flow separation near the blade midspan can be achieved. The effect of the endwall secondary flow on the blade suction surface separation at the midspan is explained with the analytical method based on the Biot–Savart Law.

LES and CDNS Investigation of T106C Low Pressure Turbine

2016 ◽  
Author(s):  
Site Hu ◽  
Chao Zhou ◽  
Zhenhua Xia ◽  
Shiyi Chen
Keyword(s):  
Secondary Flow ◽  
Flow Separation ◽  
Separated Flow ◽  
Suction Side ◽  
Low Pressure ◽  
Secondary Flows ◽  
Computational Domain ◽  
Smagorinsky Model ◽  
Low Pressure Turbine ◽  
Fine Mesh

This paper investigates the aerodynamic performance of a low pressure turbine, namely the T106C, by large eddy simulation (LES) and coarse grid direct numerical simulation (CDNS) at a Reynolds number of 100,000. The existing experimental data is used to validate the results. The effects of sub-grid scale (SGS) models, mesh densities, computational domains and boundary conditions on the result are studied. A separation zone appears downstream 60% S/S0, which is difficult to be predicted precisely. Two SGS models, i.e. Smagorinsky and WALE model are implemented. WALE model produces a better result than Smagorinsky model when the mesh is coarse. For the fine mesh, the difference due to the SGS models becomes smaller. It is surprising to find that CDNS produces very similar results to WALE model, and their results are in better agreement with the experiment than that of Smagorinsky model. The computational domain is also important for the prediction of the flow near the midspan. 3D features of the separated flow have an effect on the downstream flows, especially for the area near the reattachment. Sufficient long spanwise computational domain is important for an accurate prediction. The current study also find that the endwall secondary flow has an effect on the flow separation near the middle span, which was seldom discussed before. By considering the effects of endwall secondary flows, better prediction of the flow separation near the blade midspan can be achieved. The effect of the endwall secondary flow on the blade suction side separation is also explained with the analytical method based on the Biot-Savart Law.

Large Eddy Simulation of Secondary Flows in an Ultra-High Lift Low Pressure Turbine Cascade at Various Inlet Incidences

2020 ◽  
Vol 37 (2) ◽  
pp. 195-207
Author(s):  
Site Hu ◽  
Chao Zhou ◽  
Shiyi Chen
Keyword(s):  
Large Eddy Simulation ◽  
Engine Performance ◽  
Low Pressure ◽  
Secondary Flows ◽  
Turbine Cascade ◽  
High Lift ◽  
Blade Loading ◽  
Low Pressure Turbine ◽  
Eddy Simulation ◽  
Large Eddy

AbstractIncreasing the blade loading of a low pressure turbine blade decreases the number of blades, thus improving the aero-engine performance in terms of the weight and manufacture cost. Many studies focused on the blade-to-blade flow field of ultra-high lift low pressure turbines. The secondary flows of ultra-high lift low pressure turbines received much less attention. This paper investigates the secondary flows in an ultra-high lift low pressure turbine cascade T106C by large eddy simulation at a Reynolds number of 100,000. Both time-averaged and instantaneous flow fields of this ultra-high lift low pressure turbine are presented. To understand the effects of the inlet angle, five incidences of ‒10°, ‒5°, 0, +5° and +10° are investigated. The case at the design incidence is analyzed first. Detailed data is used to illustrate the how the fluids in boundary layers develops into secondary flows. Then, the cases with different inlet incidences are discussed. The aerodynamic performances are compared. The effect of blade loading on the vortex structures is investigated. The horseshoe vortex, passage vortex and the suction side corner vortex are very sensitive to the loading of the front part of the blade.

Large Eddy Simulation of a Low Pressure Turbine Cascade

2003 ◽  
Author(s):  
Yoshinori Ooba ◽  
Hidekazu Kodama ◽  
Chuichi Arakawa ◽  
Yuichi Matsuo ◽  
Hitoshi Fujiwara ◽  
...  
Keyword(s):  
Large Eddy Simulation ◽  
Low Pressure ◽  
Turbine Cascade ◽  
Low Pressure Turbine ◽  
Eddy Simulation ◽  
Large Eddy

Implicit Large Eddy Simulation of a Stalled Low Pressure Turbine Airfoil

2015 ◽  
Author(s):  
C. L. Memory ◽  
J. P. Chen ◽  
J. P. Bons
Keyword(s):  
Flow Field ◽  
Large Eddy Simulation ◽  
Separation Zone ◽  
Low Pressure ◽  
Numerical Code ◽  
Flow Measurements ◽  
Low Pressure Turbine ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Implicit Large Eddy Simulation

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.

Large-Eddy Simulation of Transitional Flow Through a Low-Pressure Turbine Cascade

2006 ◽  
Author(s):  
Shirdish Poondru ◽  
Urmila Ghia ◽  
Karman Ghia
Keyword(s):  
Large Eddy Simulation ◽  
Air Force ◽  
Time Integration ◽  
Low Pressure ◽  
Transitional Flow ◽  
Low Pressure Turbine ◽  
Compact Difference ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Flow Through

Subsonic, transitional flow through a low-pressure turbine (LPT) cascade is investigated using high-order compact difference scheme in conjunction with large-eddy simulation (LES). Three-dimensional simulations are performed at chord inlet Reynolds numbers (Re) of 25,000 and 50,000. The inlet Mach number is approximately 0.06. An MPI-based higher-order accurate, Chimera version of the FDL3DI flow solver developed by the Air Force Research Laboratory at Wright Patterson Air Force base, is extended for the present turbomachinery application. The implicit solver is based on an approximate factored time-integration method of Beam and Warming. Fourth-order compact-difference formulations are used for discretizing spatial derivatives in conjunction with sixth-order non-dispersive filtering. Solutions are obtained both with and without a sub-grid scale (SGS) model. A dual topology, 16-block, structured grid generated using GridPro is utilized for all simulations. The flow features are examined, and the results for both LES approaches are compared to each other, and with experimental data.

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