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  • Automated large-scale and terrain-induced turbulence modulation of atmospheric surface layer flows in a large wind tunnel
Title: Automated large-scale and terrain-induced turbulence modulation of atmospheric surface layer flows in a large wind tunnel
This study leverages a novel multi-fan flow-control instrument and a mechanized roughness element grid to simulate large- and small-scale turbulent features of atmospheric flows in a large boundary layer wind tunnel (BLWT). The flow-control instrument, termed the flow field modulator (FFM), is a computer-controlled 3 m × 6 m (2D) fan array located at the University of Florida (UF) Natural Hazard Engineering Research Infrastructure (NHERI) Experimental Facility. The system comprises 319 modular hexagonal aluminum cells, each equipped with shrouded three-blade corotating propellers. The FFM enables the active generation of large-scale turbulent structures by replicating user-specified velocity time signals to inject low-frequency fluctuations into BLWT flows. In the present work, the FFM operated in conjunction with a mechanized roughness element grid, called the Terraformer, located downstream of the FFM array. The Terraformer aided in the production of near-wall turbulent mixing through precise adjustment of the height of the roughness elements. A series of BLWT velocity profile measurement experiments were carried out at the UF BLWT test section for a set of turbulence intensity and integral length scale regimes. Input commands to the FFM and Terraformer were iteratively updated via a governing convergence algorithm (GCA) to achieve user-specified mean and turbulent flow statistics. Results demonstrate the capabilities of the FFM for significantly increasing the longitudinal integral length scales compared to conventional BLWT approaches (i.e., no active large-scale turbulence generation). The study also highlights the efficacy of the GCA scheme for attaining prescribed target mean and turbulent flow conditions at the measurement location.  more » « less
Award ID(s):
2317176
PAR ID:
10561679
Author(s) / Creator(s):
; ;
Editor(s):
Longmire, Ellen K; Westerweel, Jerry
Publisher / Repository:
Springer Nature
Date Published:
Journal Name:
Experiments in Fluids
Volume:
65
Issue:
1
ISSN:
0723-4864
Subject(s) / Keyword(s):
multi-fan turbulence atmospheric surface layer wind tunnel integral length scales large-scale testing
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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