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ICWES15 - Optimising Hydropower Generation through Fluid Dynamics Research. Presented by Dr Jessica M Andrewartha, TAS, Australia
 

ICWES15 - Optimising Hydropower Generation through Fluid Dynamics Research. Presented by Dr Jessica M Andrewartha, TAS, Australia

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    ICWES15 - Optimising Hydropower Generation through Fluid Dynamics Research. Presented by Dr Jessica M Andrewartha, TAS, Australia ICWES15 - Optimising Hydropower Generation through Fluid Dynamics Research. Presented by Dr Jessica M Andrewartha, TAS, Australia Presentation Transcript

    • Faculty of Science, Engineering & Technology Optimising Hydropower Generation Through Fluid Dynamics Research Dr Jessica Andrewartha*, Dr Jane Sargison, Xiao Lin Li School of Engineering, University of Tasmania, Australia
    • Faculty of Science, Engineering & TechnologyPresentation OverviewIntroduction • Hydropower in Tasmania • What is biofouling?Efficiency Improvements in Hydropower PipelinesPhysics of Flow over Biofilms • Real • ArtificialMitigation & ControlSummary & Conclusions Repulse Dam, Derwent River, Tasmania
    • Faculty of Science, Engineering & TechnologyIntroduction• Majority of electricity in Tasmania produced by 29 hydropower stations• Potential for hydropower in Australia well exploited – now looking at efficiency improvements• Hydropower stations require transport of water – sometimes over long distances (20 + km)• Tunnels, canals, flumes, pipelines & penstocks – susceptible to biofouling• UTAS / Hydro / ARC 10 year research collaboration on biofouling Tarraleah Penstocks, Tasmania
    • Faculty of Science, Engineering & TechnologyIntroductionBiofouling is the undesirable growth of biological matter at liquid – solid interfacesGlobal problem – causes large drag penalties3 categories: www.crestock.com/image/131228-Barnacle-Texture.aspx • Low-form gelatinous (slimes) • Filamentous • Hard depositsNatural biofilms consist of one or more components
    • Faculty of Science, Engineering & TechnologyEfficiency Improvements in Hydropower PipelinesWhy clean?• Remove biofouling from internal surface• Reduce effective wall roughness• Improve hydraulic efficiency (i.e. reduce headloss)Process: Pre-clean test ↓ Clean internal surfaces by high pressure water blasting ↓ Post-clean test
    • Faculty of Science, Engineering & TechnologyEfficiency Improvements in Hydropower PipelinesWhat was measured: • Pressure at US and DS locations • Water level (ultrasonic depth sensors) (pressure transducers) • Water temperature • Flow rate (ultrasonic flowmeters) • Machine characteristics
    • Faculty of Science, Engineering & TechnologyEfficiency Improvements in Hydropower PipelinesPower Scheme Details Wilmot Tungatinah Poatina Tarraleah Penstock Penstock 4 Penstock Hilltop PipelineOutput (MW) 35 125 300 90Operating head (m) 252 300 835 299Pipeline length (m) 526 877 1684 2141Penstock diameter (m) 1.98 1.7 - 2.3 2.6 – 3.1 2.6Improvement in 1.0 0.8 - 2.0Headloss (m)
    • Faculty of Science, Engineering & TechnologyEfficiency Improvements in Hydropower Pipelines• Biofilms increase headloss• Gains in energy production can be made by removing biofouling• Data plotted on a Moody diagram is not typical of engineering roughness• Moody diagram extensively used in industry to predict friction losses• More data over wider range of Reynolds numbers is needed• New pipe rig at UTAS will be used to gather this data • Rig in field to grow biofilms • Rig in lab for detailed testing
    • Faculty of Science, Engineering & Technology Physics of the Flow over Biofilms Do flows over biofilms conform to same structure as for typical engineering surfaces? • Grew biofilms on 1m x 0.6m test plates in hydropower canal • Drag measurements and boundary layer profiles in water tunnel • Characterised roughness using photogrammetry
    • Faculty of Science, Engineering & TechnologyPhysics of the Flow over Biofilms • Biofilms increase skin friction drag (measured up to 99% increases) • No change to mean velocity structure • Changes to turbulence structure only very close to the wall • Biofilms thicker on plates with rough surface • Drag coefficient roughly linear function of max peak- to-valley height of biofilm
    • Faculty of Science, Engineering & Technology 12.0Flow over Artificial Biofilms Streamers: black Smooth: red U = 1.0, 1.25, 1.75, 2.0 m/s• Skin friction increased by 23% 8.0 (U-u)/u*• No change to mean velocity structure 4.0• Turbulence intensity increased by 50% in region y > 1 mm out to freestream 0.0• Streamers change turbulence structure 0.0 0.5 1.0 1.5 (y+ )/• Working on capturing motion using high- 12.0 speed cameras • Find frequency of oscillation 8.0 (%) u 2 U 4.0 0.0 0.0 0.5 (y+ )/ 1.0 1.5
    • Faculty of Science, Engineering & TechnologyMitigation & Control• Dewater & physically remove fouling with brooms attached to tractors• High pressure water blast in pipelines• Chemical and heat treatment methods ineffective – majority of biofilm is dead cells and inorganic material• Long term mitigation • Provide as smooth a surface as possible • Increased wall shear – difficult for biofilms to establish • Trials of different surface coatings – some perform better than others
    • Faculty of Science, Engineering & TechnologySummary & Conclusions• Significant improvements to efficiency & generating capacity can be made by removing biofilms• Control of biofouling is a global problem, and not just in hydropower• Current research – understanding wall flows with complex organic interacting surfaces, rather than typical engineering roughnesses• Climate change policy will see greater investment in renewable energy technologies
    • Faculty of Science, Engineering & TechnologyAcknowledgementsThis research was funded by:• 3 Australian Research Council Linkage Grants• Hydro Tasmania• University of Tasmania New Appointees Research GrantThe authors also gratefully acknowledge:A. Barton, K. Perkins, G. Walker, A. Henderson, J.Osborn, A. Leith, G. Hallegraeff, P. Brandner,workshop staff at UTAS, and the many staff at HydroTasmania involved in the project.