| NSF Org: |
CMMI Division of Civil, Mechanical, and Manufacturing Innovation |
| Recipient: |
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| Initial Amendment Date: | May 27, 2014 |
| Latest Amendment Date: | May 27, 2014 |
| Award Number: | 1428954 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Joanne Culbertson
CMMI Division of Civil, Mechanical, and Manufacturing Innovation ENG Directorate for Engineering |
| Start Date: | September 1, 2014 |
| End Date: | May 31, 2019 (Estimated) |
| Total Intended Award Amount: | $921,370.00 |
| Total Awarded Amount to Date: | $921,370.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
1523 UNION RD RM 207 GAINESVILLE FL US 32611-1941 (352)392-3516 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
365 Weil Hall Gainesville FL US 32611-0001 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): | Major Research Instrumentation |
| Primary Program Source: |
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| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.041 |
ABSTRACT
MRI: Develop Inastrumentation to Advance Fundamental Research on Simulating Complex Wind Flow Near the Earth's Surface
The boundary layer wind tunnel is an essential research tool for creating dynamic wind flow that replicates the natural behavior of wind near the Earth?s surface. This wind flow is applied to models of buildings and other structures to determine their expected performance and to design them to survive extreme wind events. The accurate replication of natural wind in a laboratory is not trivial. The methods and equipment vary depending upon the wind condition (tornadoes, hurricanes, thunderstorms, etc.), and the geographic location of the object being studied (near the coast, in a suburban community, etc.). Current wind tunnel facilities are limited in this regard, each capable of addressing a small subset of wind phenomena. This award supports the development of an instrument that vastly expands the capability of a single facility to study a wide range of wind conditions observed in nature and assess how they affect the built and natural environments. This capability will accelerate the rate of discovery and open pathways to solving problems in the development of resilient infrastructure. Other applications include the study of pollutant dispersion, siting of wind energy resources, biomechanics, human perception of hazards, and micro aerial vehicle development. The project includes participants from five continents. Thus the development of this instrument will strengthen US competitiveness by enabling a breakthrough in boundary layer wind tunnel technology, while enhancing international collaboration on wind hazard issues that impact the entire populated world.
The objective is to develop an instrument capable of simulating nonstationary, non-neutral or transitioning surface flows. Examples include offshore hurricane winds flowing into a terrestrial environment, non-stationary gust fronts in thunderstorms, transient coherent structures induced by the shearing motion aloft and wind-driven rain. The instrument will command static and dynamic control devices that automatically reconfigure to achieve user-specified similarity requirements such as non-monotonic profiles, spatially variable power spectra and integral length scales, transient gusts, and rain entrainment in the flow field. These control devices must work in series (one stage conditions the next) to achieve the intended function of the instrument. The instrument includes components adapted from existing proof-of-concept studies and new technology to be developed. The framework on which the instrument is to be developed is a conventional boundary layer wind tunnel design, as a goal is to create a tool suitable for implementation in facilities worldwide.
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PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
The boundary layer wind tunnel (BLWT) is the engineer's principal experimental tool to study the behavior of wind near the earth’s surface and to determine the resultant wind pressure that acts on buildings and other civil infrastructure, i.e. the design loads.
Although we have known how to simulate conditions representative of an extreme wind event in a controlled and repeatable manner in a wind tunnel for more than 50 years, some technological gaps remain. For example, significant trial and error is often required to set up an experiment for the first time because the simulated terrain (a field of roughness elements) upwind of the test section must be manually adjusted to create the right levels of turbulence in the approach flow. Frequently occurring flow phenomena such as gust fronts, which cause rapid changes in speed and do not obey the established laws for “straight line” winds, are also difficult to recreate. Thus, this project set out to develop new technologies to precisely recreate complex flows, e.g., simulating near surface flows that evolve in time and space, while automating how the wind tunnel recreates the effects of the earth’s landscape.
The project produced an integrated system with two major subsystems to overcome these gaps. First, an automated roughness element manipulator called the “Terraformer” was designed and built to achieve user-specified flow conditions within minutes. Consisting of 1116 integrated stepper motor assemblies, the Terraformer precisely rotates and translate roughness elements independently from one another to control height and aspect ratio. The system was brought online in 2015, becoming available to researchers across the country in 2016 through the NSF Natural Hazards Engineering Research Infrastructure (NHERI) program. To date, more than one dozen NSF awards have used the Terraformer, with more projects inbound and planned for its near-term use.
The second major subsystem is a flow conditioning device located upwind of the Terraformer called the Flow Field Modulator (FFM). It consists of 319 individually controlled fans, each powered by ~1 hp motors that can change the propeller speed from zero to full speed in less than 1/5 of a second. The ability to change the velocity in each cell independently imparts the ability to recreate non-traditional flows in the tunnel, ranging from a geometrically scaled thunderstorm outflow to the turbulent conditions a UAV may experience flying through an urban environment. The system is expected to become available to NHERI users in early 2020.
More than 20 students, staff members, and faculty contributed to the project, with the lead PhD student graduating in 2019 and returning as a research scientist to support future NHERI users with the implementation of the system.
Last Modified: 09/22/2019
Modified by: Forrest J Masters
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