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This content will become publicly available on November 17, 2018

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

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:
Report Number(s):
LA-UR-17-23268
Journal ID: ISSN 1095-4244
Grant/Contract Number:
AC52-06NA25396
Type:
Accepted Manuscript
Journal Name:
Wind Energy
Additional Journal Information:
Journal Name: Wind Energy; Journal ID: ISSN 1095-4244
Publisher:
Wiley
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
Country of Publication:
United States
Language:
English
Subject:
17 WIND ENERGY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; actuator line method; low-level jet; velocity deficit; vertical flux of kinetic energy; wake recovery; wind farm
OSTI Identifier:
1411349