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Title: Large-eddy simulations of wind-farm wake characteristics associated with a low-level jet

Abstract

Here, we performed a suite of flow simulations for a 12-wind-turbine array with varying inflow conditions and lateral spacings, and compared the impacts of the flow on velocity deficit and wake recovery. We imposed both laminar inflow and turbulent inflows, which contain turbulence for the Ekman layer and a low-level jet (LLJ) in the stable boundary layer. To solve the flow through the wind turbines and their wakes, we used a large-eddy simulation technique with an actuator-line method. We compared the time series for the velocity deficit at the first and rear columns to observe the temporal change in velocity deficit for the entire wind farm. The velocity deficit at the first column for LLJ inflow was similar to that for laminar inflow. However, the magnitude of velocity deficit at the rear columns for the case with LLJ inflow was 11.9% greater because of strong wake recovery, which was enhanced by the vertical flux of kinetic energy associated with the LLJ. In order to observe the spatial transition and characteristics of wake recovery, we performed statistical analyses of the velocity at different locations for both the laminar and LLJ inflows. These studies indicated that strong wake recovery was present, andmore » a kurtosis analysis showed that the probability density function for the streamwise velocity followed a Gaussian distribution. In a quadrant analysis of the Reynolds stress, we found that the ejection and sweep motions for the LLJ inflow case were greater than those for the laminar inflow case.« less

Authors:
 [1]; ORCiD logo [2];  [3]; ORCiD logo [2];  [1]; ORCiD logo [4]; ORCiD logo [1]
  1. Yonsei Univ., Seoul (South Korea). Dept. of Mechanical Engineering
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Earth and Environmental Science
  3. Korea Inst. of Atmospheric Prediction Systems, Seoul (South Korea)
  4. National Center for Atmospheric Research, Boulder, CO (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
Ministry of Trade, Industry, and Energy (MOTIE); National Research Foundation of Korea (NRF); USDOE
OSTI Identifier:
1411349
Report Number(s):
LA-UR-17-23268
Journal ID: ISSN 1095-4244
Grant/Contract Number:  
AC52-06NA25396
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Wind Energy
Additional Journal Information:
Journal Volume: 21; Journal Issue: 3; Journal ID: ISSN 1095-4244
Publisher:
Wiley
Country of Publication:
United States
Language:
English
Subject:
17 WIND ENERGY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; Earth Sciences

Citation Formats

Na, Ji Sung, Koo, Eunmo, Jin, Emilia Kyung, Linn, Rodman, Ko, Seung Chul, Muñoz-Esparza, Domingo, and Lee, Joon Sang. Large-eddy simulations of wind-farm wake characteristics associated with a low-level jet. United States: N. p., 2017. Web. doi:10.1002/we.2152.
Na, Ji Sung, Koo, Eunmo, Jin, Emilia Kyung, Linn, Rodman, Ko, Seung Chul, Muñoz-Esparza, Domingo, & Lee, Joon Sang. Large-eddy simulations of wind-farm wake characteristics associated with a low-level jet. United States. doi:10.1002/we.2152.
Na, Ji Sung, Koo, Eunmo, Jin, Emilia Kyung, Linn, Rodman, Ko, Seung Chul, Muñoz-Esparza, Domingo, and Lee, Joon Sang. Fri . "Large-eddy simulations of wind-farm wake characteristics associated with a low-level jet". United States. doi:10.1002/we.2152. https://www.osti.gov/servlets/purl/1411349.
@article{osti_1411349,
title = {Large-eddy simulations of wind-farm wake characteristics associated with a low-level jet},
author = {Na, Ji Sung and Koo, Eunmo and Jin, Emilia Kyung and Linn, Rodman and Ko, Seung Chul and Muñoz-Esparza, Domingo and Lee, Joon Sang},
abstractNote = {Here, we performed a suite of flow simulations for a 12-wind-turbine array with varying inflow conditions and lateral spacings, and compared the impacts of the flow on velocity deficit and wake recovery. We imposed both laminar inflow and turbulent inflows, which contain turbulence for the Ekman layer and a low-level jet (LLJ) in the stable boundary layer. To solve the flow through the wind turbines and their wakes, we used a large-eddy simulation technique with an actuator-line method. We compared the time series for the velocity deficit at the first and rear columns to observe the temporal change in velocity deficit for the entire wind farm. The velocity deficit at the first column for LLJ inflow was similar to that for laminar inflow. However, the magnitude of velocity deficit at the rear columns for the case with LLJ inflow was 11.9% greater because of strong wake recovery, which was enhanced by the vertical flux of kinetic energy associated with the LLJ. In order to observe the spatial transition and characteristics of wake recovery, we performed statistical analyses of the velocity at different locations for both the laminar and LLJ inflows. These studies indicated that strong wake recovery was present, and a kurtosis analysis showed that the probability density function for the streamwise velocity followed a Gaussian distribution. In a quadrant analysis of the Reynolds stress, we found that the ejection and sweep motions for the LLJ inflow case were greater than those for the laminar inflow case.},
doi = {10.1002/we.2152},
journal = {Wind Energy},
number = 3,
volume = 21,
place = {United States},
year = {Fri Nov 17 00:00:00 EST 2017},
month = {Fri Nov 17 00:00:00 EST 2017}
}

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Works referenced in this record:

Numerical simulations of wake interaction between two wind turbines at various inflow conditions
journal, October 2010

  • Troldborg, Niels; Larsen, Gunner C.; Madsen, Helge A.
  • Wind Energy, Vol. 14, Issue 7, p. 859-876
  • DOI: 10.1002/we.433

Optimal turbine spacing in fully developed wind farm boundary layers
journal, April 2011

  • Meyers, Johan; Meneveau, Charles
  • Wind Energy, Vol. 15, Issue 2, p. 305-317
  • DOI: 10.1002/we.469