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Brian Polagye

Adjunct Investigator

Assistant Professor, Mechanical Engineering

Email

bpolagye@u.washington.edu

Phone

206-543-7544

Research Interests

Tidal Energy Site and Device Characterization

Biosketch

Brian Polagye specializes in the characterization of tidal energy sites and devices through his work with the Northwest National Marine Renewable Energy Center. He works closely with Dr. Jim Thomson to develop instrumentation and methodologies to characterize the physical and biological environments at tidal energy sites. A combination of shipboard and stand-alone surveys monitor current velocity, turbulence, water quality, underwater noise, and marine mammal behavior. These activities are essential to the effective siting of tidal energy devices.

Publications

2000-present and while at APL-UW

Noise correction of turbulent spectra obtained from acoustic Doppler velocimeters

Durgesh, V., J. Thomson, M. Richmond, and B. Polagye, "Noise correction of turbulent spectra obtained from acoustic Doppler velocimeters," Flow Meas. Instrum., 37, 29-41, doi:10.1016/j.flowmeasinst.2014.03.001, 2014.

More Info

1 Jun 2014

Velocity spectra are essential in characterizing turbulent flows. The Acoustic Doppler Velocimeter (ADV) provides three-dimensional time series data at a single point in space which are used for calculating velocity spectra. However, ADV data are susceptible to contamination from various sources, including instrument noise, which is the intrinsic limit to the accuracy of acoustic Doppler processing. This contamination results in a flattening of the velocity spectra at high frequencies (O(10)Hz).

This paper demonstrates two elementary methods for attenuating instrument noise and improving velocity spectra. First, a "Noise Auto-Correlation" (NAC) approach utilizes the correlation and spectral properties of instrument noise to identify and attenuate the noise in the spectra. Second, a Proper Orthogonal Decomposition (POD) approach utilizes a modal decomposition of the data and attenuates the instrument noise by neglecting the higher-order modes in a time-series reconstruction. The methods are applied to ADV data collected in a tidal channel with maximum horizontal mean currents up to 2 m/s. The spectra estimated using both approaches exhibit an f-5/3 slope, consistent with a turbulent inertial sub-range, over a wider frequency range than the raw spectra. In contrast, a Gaussian filter approach yields spectra with a sharp decrease at high frequencies.

In an example application, the extended inertial sub-range from the NAC method increased the confidence in estimating the turbulent dissipation rate, which requires fitting the amplitude of the f-5/3 region. The resulting dissipation rates have smaller uncertainties and are more consistent with an assumed local balance to shear production, especially for mean horizontal currents less than 0.8 m/s.

Integrated instrumentation for marine energy monitoring

Polagye, B., J. Joslin, A. Stewart, and A. Copping, "Integrated instrumentation for marine energy monitoring," Proc., 2nd International Conference on Environmental Interactions of Marine Renewable Energy Technologies (EIMR 2014), 28 April - 2 May, Stornaway, Isle of Lewis, Scotland (2014).

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28 Apr 2014

Integrated instrumentation packages designed for operation at marine renewable energy sites have the potential to reduce the risk uncertainty around high- priority interactions between stressors and receptors. Such packages can leverage the competitive strengths of individual instruments and reduce risk in a rapid, cost-effective manner. One emerging example of environmental infrastructure to achieve these objectives, the Adaptable Monitoring Package, is presented and its capabilities described. The development and adoption of such packages requires close coordination between resource managers, technology developers, and researchers.

Development of an adaptable monitoring package for marine renewable energy projects. Part II: Hydrodynamic performance

Joslin, J., B. Polagye, A. Stewart, and B. Rush, "Development of an adaptable monitoring package for marine renewable energy projects. Part II: Hydrodynamic performance," Proc., 2nd Marine Energy Technology Symposium (METS 2014), 15-18 April, Seattle, WA (2014).

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15 Apr 2014

The Adaptable Monitoring Package (AMP), along with a remotely operated vehicle (ROV) and custom tool skid, is being developed to support near-field (≤ 10 meters) monitoring of hydrokinetic energy converters. The AMP is intended to support a wide range of environmental monitoring in harsh oceanographic conditions, at a cost in line with other aspects of technology demonstrations. This paper, which is the second in a two part series, covers the hydrodynamic analysis of the AMP and deployment ROV given the strong waves and currents that typify marine renewable energy sites. Hydrodynamic conditions from the Pacific Marine Energy Center's wave test sites (PMEC) and Admiralty Inlet, Puget Sound, Washington are considered as early adoption case studies. A methodology is presented to increase the AMP's capabilities by optimizing its drag profile through a combination of computational fluid dynamic (CFD) modeling and sub-scale experiments. Preliminary results suggest that AMP deployments should be possible in turbulent environments with a mean flow velocity up to 1 m/s.

More Publications

Development of an adaptable monitoring package for marine renewable energy projects. Part I: Conceptual design and operation

Rush, B., J. Joslin, A. Stewart, and B. Polagye, "Development of an adaptable monitoring package for marine renewable energy projects. Part I: Conceptual design and operation," Proc., 2nd Marine Energy Technology Symposium (METS 2014), 15-18 April, Seattle, WA (2014).

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15 Apr 2014

Environmental monitoring of marine renewable energy projects is needed to reduce environmental uncertainties and en- able sustainable commercial implementations. An Adaptable Monitoring Package (AMP), along with the support infrastruc- ture required to perform maintenance of the AMP, is being de- veloped to enable real-time environmental monitoring of marine renewable energy converters. The monitoring capabilities sup- ported by the AMP include marine animal interactions with con- verters, noise levels, current and wave fields, and water qual- ity. The core instrumentation on the AMP is comprised of a hy- brid stereo-optical and acoustical camera system, a localizing hy- drophone array, acoustic Doppler current profilers and velocime- ters, a water quality sensor, cetacean click detector, and fish tag receiver. For an initial deployment to monitor a tidal turbine in deep water, the AMP is integrated into the converter structure and connected to shore via the turbine export cable, but can be dis- connected and recovered for maintenance independently of the turbine. The AMP is deployed by a SeaEye Falcon inspection- class ROV and a custom tool skid. This paper describes the func- tion, design, and dynamic stability of the AMP and deployment ROV. The conceptual design and approach to operations, to be confirmed through field testing, suggests that the AMP is likely to meet the need for high-bandwidth monitoring of marine re- newable energy converters at an acceptable cost.

Method for identification of Doppler noise levels in turbulent flow measurements dedicated to tidal energy

Richard, J-.B., J. Thomson, B. Polagye, and J. Bard, "Method for identification of Doppler noise levels in turbulent flow measurements dedicated to tidal energy," Int. J. Mar. Energy, 3-4, 52-64, doi:10.1016/j.ijome.2013.11.005, 2013.

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1 Dec 2013

Acoustic Doppler sensors used for flow measurements at energetic tidal sites present an inherent "Doppler noise" in the measured signal, varying with hardware configuration and flow conditions. At scales comparable to the sensors' sampling frequencies, the corresponding perturbations notably contaminate the signal, and cannot be corrected in the time series.

At such scales, dynamic phenomena are of particular interest in the process of increasing reliability and effectiveness of tidal turbines, and are mostly addressed in terms of statistics. In the case of inflow speed variations, the bias due to Doppler noise should be taken into account, and can be assessed via manufacturer specifications.

Here, a method is presented that enables a direct estimation of the Doppler noise strength from the measured signal itself. Inspired from polynomial least square regression, it is based on a spectral analysis of the measured signal respect to turbulence theory, under the hypothesis of a white Doppler noise contamination. The subsequent limitations are discussed and illustrated by practical cases.

The values found are generally higher than suggested by manufacturers, but still in the same order of magnitude. The use of the highest sampling frequency available is recommended.

Development of an adaptable monitoring package for marine renewable energy

Joslin, J., E. Celkis, C. Roper, A. Stewart, and B. Polagye, "Development of an adaptable monitoring package for marine renewable energy," Proc., Oceans, 23-27 September, San Diego, 8 pp (MTS/IEEE, 2013).

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23 Sep 2013

The Adaptable Monitoring Package (AMP) along with a Remotely Operated Vehicle (ROV) and custom tool skid, is being developed to support near-field (󖼚 meters) and long-range monitoring of hydrokinetic energy converters. The goal for the AMP is to develop a system capable of supporting a wide range of environmental monitoring in harsh oceanographic conditions, at a cost in line with other aspects of technology demonstrations. This paper presents a system description of all related infrastructure for the AMP, including supported instrumentation, deployment ROV and tool skid, launch platform, and docking station. Design requirements are driven by the monitoring instrumentation and the strong waves and currents that typify marine renewable energy sites. Hydrodynamic conditions from the Pacific Marine Energy Centers wave test sites and Admiralty Inlet, Puget Sound, Washington are considered in the design as early adoption case studies. A methodology is presented to increase the capabilities to deploy and operate the AMP in strong currents by augmenting thrust and optimizing the system drag profile through computational fluid dynamic modeling. Preliminary results suggest that the AMP should be deployable in turbulent environments with mean flow velocities up to 1 m/s.

Resource mapping at tidal energy sites

Palodichuk, M., B. Polagye, and J. Thomson, "Resource mapping at tidal energy sites," IEEE J. Ocean. Eng., 38, 433-446, doi:10.1109/JOE.2012.2227578, 2013.

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1 Jul 2013

Station keeping, a vessel-based spatial surveying method for resolving details of the hydrokinetic resource, is presented in the context of the general methodology and also for the specific case of a survey conducted in northern Admiralty Inlet, Puget Sound, WA, in June 2011. The acoustic Doppler current profiler (ADCP) measurements collected during the June 2011 survey were part of a broader effort to characterize the resource at this location before tidal turbine installation. Autonomous bottom-lander (bottom-mounted) ADCP measurements are used to evaluate the accuracy with which data collected from this vessel-based survey reflect stationary measurements and also to analyze the potential for cycle-to-cycle variations in the conclusions drawn. Results indicate good agreement between shipboard and bottom-mounted observations in capturing spatial resource differences. Repeated surveys over several tidal cycles are required to obtain results consistent with long-term observations. Station-keeping surveys help to optimize bottom-mounted ADCP deployments that are then used to estimate turbine power generation potential and make final siting decisions.

Sediment-generated noise and bed stress in a tidal channel

Bassett, C., J. Thomson, and B. Polagye, "Sediment-generated noise and bed stress in a tidal channel," J. Geophys. Res., 118, 2249-2265, doi:10.1002/jgrc.20169, 2013.

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30 Apr 2013

Tidally driven currents and bed stresses can result in noise generated by moving sediments. At a site in Admiralty Inlet, Puget Sound, Washington State (USA), peak bed stresses exceed 20 Pa. Significant increases in noise levels are attributed to mobilized sediments at frequencies from 4–30 kHz with more modest increases noted from 1–4 kHz. Sediment-generated noise during strong currents masks background noise from other sources, including vessel traffic. Inversions of the acoustic spectra for equivalent grain sizes are consistent with qualitative data of the seabed composition. Bed stress calculations using log layer, Reynolds stress, and inertial dissipation techniques generally agree well and are used to estimate the shear stresses at which noise levels increase for different grain sizes. Regressions of the acoustic intensity versus near-bed hydrodynamic power demonstrate that noise levels are highly predictable above a critical threshold despite the scatter introduced by the localized nature of mobilization events.

Implications of tidal phasing for power generation at a tidal energy site

Polagye, B., and J. Thomson, "Implications of tidal phasing for power generation at a tidal energy site," in Proc., 1st Marine Energy Technology Symposium, MET13, 10-11 April, Washington, D.C., 2013.

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10 Apr 2013

Spatial resource gradients have been observed at a number of proposed tidal energy sites. However, these gradients are typically quantified using the first or second moments (i.e., mean or standard deviation) of time series which obscures information about the co%u2010temporal amplitude and phase variation. These co%u2010temporal variations have a number of interesting implications for power production from arrays of tidal turbines. Here, co%u2010temporal time series data from several locations in northern Admiralty Inlet, Puget Sound, Washington (USA) are used to investigate phase variations in kinetic power density over length scales of less than 5 km. Results demonstrate that large phase variations in kinetic power density are routinely produced by phase variations in the harmonic and aharmonic currents. However, exploiting these phase variations in a way that reduces power generation intermittency requires that locations which are out of phase have similar mean kinetic power density and intermittency. Further investigation of local phasing at tidal energy sites of commercial interest is recommended.

Tidal turbulence spectra from a compliant mooring

Thomson, J., L. Kilcher, M. Richmond, J. Talbert, A. deKlerk, B. Polagye, M. Guerra, and R. Cienfuegos, "Tidal turbulence spectra from a compliant mooring," Proc., 1st Marine Energy Technology Symposium, METS2013, 10-11 April, Washington, D.C., 2013.

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10 Apr 2013

A compliant mooring to collect high frequency turbulence data at a tidal energy site is evaluated in a series of short demonstration deployments. The Tidal Turbulence Mooring (TTM) improves upon recent bottom-mounted approaches by suspending Acoustic Doppler Velocimeters (ADVs) at mid-water depths (which are more relevant to tidal turbines). The ADV turbulence data are superior to Acoustic Doppler Current Profiler (ADCP) data, but are subject to motion contamination when suspended on a mooring in strong currents. In this demonstration, passive stabilization is shown to be sufficient for acquiring bulk statistics of the turbulence, without motion correction. With motion correction (post-processing), data quality is further improved. Results from two field sites are compared, and the differences are attributed to the generation of large eddies by headlands and sills.

A vessel noise budget for Admiralty Inlet, Puget Sound, Washington (USA)

Bassett, C., B. Polagye, M. Holt, and J. Thomson, "A vessel noise budget for Admiralty Inlet, Puget Sound, Washington (USA)," J. Acoust. Soc. Am., 132, 3706-3719, doi:10.1121/1.4763548, 2012.

More Info

1 Dec 2012

One calendar year of Automatic Identification System (AIS) ship-traffic data was paired with hydrophone recordings to assess ambient noise in northern Admiralty Inlet, Puget Sound, WA (USA) and to quantify the contribution of vessel traffic. The study region included inland waters of the Salish Sea within a 20 km radius of the hydrophone deployment site. Spectra and hourly, daily, and monthly ambient noise statistics for unweighted broadband (0.02–30 kHz) and marine mammal, or M-weighted, sound pressure levels showed variability driven largely by vessel traffic. Over the calendar year, 1363 unique AIS transmitting vessels were recorded, with at least one AIS transmitting vessel present in the study area 90% of the time. A vessel noise budget was calculated for all vessels equipped with AIS transponders. Cargo ships were the largest contributor to the vessel noise budget, followed by tugs and passenger vessels. A simple model to predict received levels at the site based on an incoherent summation of noise from different vessels resulted in a cumulative probability density function of broadband sound pressure levels that shows good agreement with 85% of the temporal data.

In The News

AMPing up underwater environmental monitoring

UW News, Chelsea Yates

Researchers have long been interested in better understanding how marine energy affects underwater environments, and thanks to UW engineers, they may be a big step closer.

26 Jul 2017

"Millennium Falcon" launches "X-Wing" into marine world

Marine Technology News, Eric Haun

The long-term effect of renewable energy installations on marine animals is to be investigated by researchers at Washington University. APL-UW Ocean Engineers Andy Stewart, Ben Rush, Paul Gibbs, Trina Litchendorf, Tim McGinnis, and Chris Siani are involved in this R&D project.

5 May 2015

New tool monitors effects of tidal, wave energy on marine habitat

UW News and Information, Michelle Ma

A new robot will deploy instruments to gather information in unprecedented detail about how marine life interacts with underwater equipment used to harvest wave and tidal energy.

5 Feb 2015

More News Items

U.S. Navy awards $8 million to develop wave, tidal energy technology

UW News and Information, Hannah Hickey

The U.S. Navy has committed to get half of its energy from renewable sources by the year 2020. The University of Washington is helping to reach that goal with an $8 million, four-year contract from the Naval Facilities Engineering Command, or NAVFAC, to develop marine renewable energy for use at the Navy's facilities worldwide.

24 Oct 2014

Feds approve Puget Sound tidal energy project

KUOW Radio, Courtney Flatt

A proposal for the world%u2019s first grid-connected tidal energy project received a federal license. The project has been almost eight years in the making.

20 Mar 2014

Beyond the forecast: Power play

KING5 News, Seattle

Washington State is on the forefront of green energy production, including harnessing winds, tides, and sunlight to produce electricity.

23 Nov 2013

Noisy ships, ferries create racket below Puget Sound

The Seattle Times, Craig Welch

Recent work by University of Washington researchers shows noise in some Puget Sound shipping channels regularly meets or exceeds levels the federal government suggests may be harmful to marine life.

3 Jan 2013

Currents of Change

Seattle Business Magazine, Amelia Apfel

Local experts rely on teamwork and patience to bring tidal power to the Northwest.

1 Jul 2010

Concerns emerge about environmental effects of wave-energy technology

The Seattle Times, Michelle Ma

Energy generated from the ocean's waves and tides might be the next source of "green" power in our region, but the technology demands more study. A new marine renewable-energy research center has been launched, giving the University of Washington the lead for tidal-power research.

17 Nov 2008

Inventions

An Adaptable Monitoring Package for Marine Environmental Monitoring

Record of Invention Number: 47352

Brian Polagye, James Joslin, Ben Rush, Andy Stewart

Disclosure

21 May 2015

Acoustics Air-Sea Interaction & Remote Sensing Center for Environmental & Information Systems Center for Industrial & Medical Ultrasound Electronic & Photonic Systems Ocean Engineering Ocean Physics Polar Science Center
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