Numerical simulations of the flow field and pollutant dispersion in an idealized urban area under different atmospheric stability conditions

The turbulent flow field in a practical gas turbine combustor is very complex because of the interactions between various flows resulting from components like multiple types of swirlers, dilution holes, and liner effusion cooling holes. Numerical simulations of flows in such complex combustor configurations are challenging. The challenges result from (a) the complexities of the interfaces between multiple three-dimensional shear layers, (b) the need for proper treatment of a large number of tiny effusion holes with multiple angles, and (c) the requirements for fast turnaround times in support of engineering design optimization. Both the Reynolds averaged Navier–Stokes simulation (RANS) and the large eddy simulation (LES) for the practical combustor geometry are considered. An autonomous meshing using the cut-cell Cartesian method and adaptive mesh refinement (AMR) is demonstrated for the first time to simulate the flow in a practical combustor geometry. The numerical studies include a set of computations of flows under a prescribed pressure drop across the passage of interest and another set of computations with all passages open with a specified total flow rate at the plenum inlet and the pressure at the exit. For both sets, the results of the RANS and the LES flow computations agree with each other and with the corresponding measurements. The results from the high-resolution LES simulations are utilized to gain fundamental insights into the complex turbulent flow field by examining the profiles of the velocity, the vorticity, and the turbulent kinetic energy. The dynamics of the turbulent structures are well captured in the results of the LES simulations.

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An Analytic Model for Dispersion of Rocket Exhaust Clouds: Specifications and Analysis in Different Atmospheric Stability Conditions

Journal of Aerospace Technology and Management ◽

10.5028/jatm.v7i3.510 ◽

2015 ◽

Vol 7 (3) ◽

pp. 374-385 ◽

Cited By ~ 2

Author(s):

Bruno Kabke Bainy ◽

Daniela Buske ◽

Régis Sperotto Quadros

Keyword(s):

Atmospheric Stability ◽

Stability Conditions ◽

Analytic Model ◽

Rocket Exhaust

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Can Wind Lidars Measure Turbulence?

Journal of Atmospheric and Oceanic Technology ◽

10.1175/jtech-d-10-05004.1 ◽

2011 ◽

Vol 28 (7) ◽

pp. 853-868 ◽

Cited By ~ 103

Author(s):

A. Sathe ◽

J. Mann ◽

J. Gottschall ◽

M. S. Courtney

Keyword(s):

Continuous Wave ◽

Atmospheric Stability ◽

Test Site ◽

Systematic Errors ◽

Stability Conditions ◽

Pass Filter ◽

Low Pass Filter ◽

Wind Speeds ◽

Sonic Anemometers ◽

Velocity Variance

Abstract Modeling of the systematic errors in the second-order moments of wind speeds measured by continuous-wave (ZephIR) and pulsed (WindCube) lidars is presented. These lidars use the conical scanning technique to measure the velocity field. The model captures the effect of volume illumination and conical scanning. The predictions are compared with the measurements from the ZephIR, WindCube, and sonic anemometers at a flat terrain test site under different atmospheric stability conditions. The sonic measurements are used at several heights on a meteorological mast in combination with lidars that are placed on the ground. Results show that the systematic errors are up to 90% for the vertical velocity variance, whereas they are up to 70% for the horizontal velocity variance. For the ZephIR, the systematic errors increase with height, whereas for the WindCube, they decrease with height. The systematic errors also vary with atmospheric stability and are low for unstable conditions. In general, for both lidars, the model agrees well with the measurements at all heights and under different atmospheric stability conditions. For the ZephIR, the model results are improved when an additional low-pass filter for the 3-s scan is also modeled. It is concluded that with the current measurement configuration, these lidars cannot be used to measure turbulence precisely.

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