TWO DIMENSIONAL DIRECT NUMERICAL AND LARGE EDDY SIMULATION OF SHOCK-TURBULENT MIXING LAYER INTERACTION USING DIFFERENT SGS MODELS

Turbulent mixing layers are canonical flow in nature and engineering, and deserve comprehensive studies under various conditions using different methods. In this paper, turbulent mixing layers are investigated using large eddy simulation and dynamic mode decomposition. The accuracy of the computations is verified and validated. Standard dynamic mode decomposition is utilized to flow decomposition, reconstruction and prediction. It was found that the dominant-mode selection criterion based on mode amplitude is more suitable for turbulent mixing layer flow compared with the other three criteria based on singular value, modal energy and integral modal amplitude, respectively. For the mixing layer with random disturbance, the standard dynamic mode decomposition method could accurately reconstruct and predict the region before instability happens, but is not qualified in the regions after that, which implies that improved dynamic mode decomposition methods need to be utilized or developed for the future dynamic mode decomposition of turbulent mixing layers.

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Trailing Edge 3D Free Shear Layers

Volume 1: Aircraft Engine; Marine; Turbomachinery; Microturbines and Small Turbomachinery ◽

10.1115/2000-gt-0436 ◽

2000 ◽

Cited By ~ 1

Author(s):

N. Schröder ◽

G. Hofmann ◽

J. Hourmouziadis

Keyword(s):

Flow Field ◽

Large Eddy Simulation ◽

Vortex Breakdown ◽

Mixing Layer ◽

Streamwise Vortex ◽

Two Dimensional ◽

Development Length ◽

Trailing Edge ◽

Eddy Simulation ◽

Large Eddy

This paper reports on an investigation of coherent structures and the characteristic flow field of trailing edge shed vorticity, which can be found downstream of blade rows as well as behind lobed exhaust mixers. The corresponding, fundamental flow case of a free, skewed mixing layer was studied both experimentally in a low-speed test facility and numerically using Standard k,ε-Model and Large Eddy Simulation (LES). The investigation gave a new insight into the flow structure. Along the complete development length there is a coexistence of the streamwise vortices generated by cross-shear with the spanwise vorticity of Von-Karman vortex street or two-dimensional Kelvin-Helmholtz instability. This was confirmed by extensive flow-field measurements using five-hole probes and X-wire anemometry as well as by CFD. The measurement of the mixing layer spreading resulted in a growth rate of the skewed mixing layer very similar to that of the two-dimensional flow. The development of energy thickness downstream of the trailing edge, representing the mixing losses, was found to be practically independent of skewing angle. The spacing and the fluctuation of the streamwise vortex cores were not accessible to probe measurement, but were determined by visualization and large eddy simulation. The separation of vorticity-components gave stable distributions in streamwise and spanwise direction until vortex breakdown, which appears to be independent of the initial state of the boundary layer. A criterion for streamwise vortex breakdown was identified by correcting the development length with the equivalent shear layer parameter. The content of turbulent kinetic energy as a measure for turbulence production and mixing efficiency is discussed.

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