Comparison of DDES and URANS for Unsteady Tip Leakage Flow in an Axial Compressor RotorSource: Journal of Fluids Engineering:;2019:;volume( 141 ):;issue: 012::page 121405DOI: 10.1115/1.4043774Publisher: American Society of Mechanical Engineers (ASME)
Abstract: Tip leakage vortex (TLV) has a large impact on compressor performance and should be accurately predicted by computational fluid dynamics (CFD) methods. New approaches of turbulence modeling, such as delayed detached eddy simulation (DDES), have been proposed, the computational resources of which can be reduced much more than for large eddy simulation (LES). In this paper, the numerical simulations of the rotor in a low-speed large-scale axial compressor based on DDES and unsteady Reynolds-averaged Navier–Stokes (URANS) are performed, thus improving our understanding of the TLV dynamic mechanisms and discrepancy of these two methods. We compared the influence of different time steps in the URANS simulation. The widely used large time-step makes the unsteadiness extremely weak. The small time-step shows a better result close to DDES. The time-step scale is related to the URANS unsteadiness and should be carefully selected. In the time-averaged flow, the TLV in DDES dissipates faster, which has a more similar structure to the experiment. Then, the time-averaged and instantaneous results are compared to divide the TLV into three parts. URANS cannot give the loss of stability and evolution details of TLV. The fluctuation velocity spectra show that the amplitude of high frequencies becomes obvious downstream from the TLV, where it becomes unstable. Last, the anisotropy of the Reynolds stress of these two methods is analyzed through the Lumley triangle to see the distinction between the methods and obtain the Reynolds stress. The results indicate that the TLV latter part in DDES is anisotropic, while in URANS it is isotropic.
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contributor author | Liu, Yangwei | |
contributor author | Zhong, Luyang | |
contributor author | Lu, Lipeng | |
date accessioned | 2019-09-18T09:02:01Z | |
date available | 2019-09-18T09:02:01Z | |
date copyright | 6/17/2019 12:00:00 AM | |
date issued | 2019 | |
identifier issn | 0098-2202 | |
identifier other | fe_141_12_121405 | |
identifier uri | http://yetl.yabesh.ir/yetl1/handle/yetl/4258073 | |
description abstract | Tip leakage vortex (TLV) has a large impact on compressor performance and should be accurately predicted by computational fluid dynamics (CFD) methods. New approaches of turbulence modeling, such as delayed detached eddy simulation (DDES), have been proposed, the computational resources of which can be reduced much more than for large eddy simulation (LES). In this paper, the numerical simulations of the rotor in a low-speed large-scale axial compressor based on DDES and unsteady Reynolds-averaged Navier–Stokes (URANS) are performed, thus improving our understanding of the TLV dynamic mechanisms and discrepancy of these two methods. We compared the influence of different time steps in the URANS simulation. The widely used large time-step makes the unsteadiness extremely weak. The small time-step shows a better result close to DDES. The time-step scale is related to the URANS unsteadiness and should be carefully selected. In the time-averaged flow, the TLV in DDES dissipates faster, which has a more similar structure to the experiment. Then, the time-averaged and instantaneous results are compared to divide the TLV into three parts. URANS cannot give the loss of stability and evolution details of TLV. The fluctuation velocity spectra show that the amplitude of high frequencies becomes obvious downstream from the TLV, where it becomes unstable. Last, the anisotropy of the Reynolds stress of these two methods is analyzed through the Lumley triangle to see the distinction between the methods and obtain the Reynolds stress. The results indicate that the TLV latter part in DDES is anisotropic, while in URANS it is isotropic. | |
publisher | American Society of Mechanical Engineers (ASME) | |
title | Comparison of DDES and URANS for Unsteady Tip Leakage Flow in an Axial Compressor Rotor | |
type | Journal Paper | |
journal volume | 141 | |
journal issue | 12 | |
journal title | Journal of Fluids Engineering | |
identifier doi | 10.1115/1.4043774 | |
journal fristpage | 121405 | |
journal lastpage | 121405-13 | |
tree | Journal of Fluids Engineering:;2019:;volume( 141 ):;issue: 012 | |
contenttype | Fulltext |