Carolin Friz


Last Name

Friz

First Name

Carolin

ORCID

0009-0006-9342-2588

Organisational unit

03820 - Boes, Robert / Boes, Robert

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2024 - 20254
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Publications 1 - 4 of 4
  • Auswirkung der Sohlenrauheit von Schussrinnen auf die Entwicklung der Wasser-Luft-Strömung
    Item type: Journal Article
    Friz, Carolin; Bürgler, Matthias; Hohermuth, Benjamin; et al. (2025)
    WasserWirtschaft
    Schussrinnen an Talsperren sichern die Hochwasserableitung. Ihre steilen Neigungen führen zu einer schwerkraftbedingten Beschleunigung des Abflusses, die an der Gerinnesohle Turbulenzen erzeugt und zur Selbstbelüftung des Abflusses führt. Ein angemessenes Prozessverständnis ist für die präzise Schussrinnenbemessung entscheidend. An einem großskaligen Versuchsmodell wurden mit modernster Messtechnik umfassende Experimente durchgeführt, deren Ergebnisse zur Kenntnis über hochenergetische Wasser-Luft-Strömungen und die Dimensionierung von Hochwasserentlastungsanlagen beitragen. Reservoir dams are critical for hydropower, irrigation, and flood protection, with spillways serving as essential safety outlets for flood waters. Their steep slopes produce high flow velocities, while turbulence at the spillway invert interacts with the free surface to induce self-aeration, resulting in “white waters”. A thorough understanding of these phenomena is vital for the robust design of spillways. However, progress in quantitatively describing these processes is limited by scarce, comprehensive air-water flow data downstream of the aeration inception point. Experiments on a large-scale physical model, with systematic variations in discharge and invert roughness, employed advanced instrumentation such as laser Doppler anemometry and dual-tip conductivity probes to measure flow velocities and air concentrations. Video analysis was used to determine a reference inception point. This study deepens our insight into high energy air-water flows and supports improved design of spillways.
  • Developing a customized laboratory setup to assess sensors for real-time suspended sediment monitoring
    Item type: Conference Paper
    Friz, Carolin; Felix, David; Evers, Frederic M.; et al. (2024)
    IOP Conference Series: Earth and Environmental Science
    Sedimentation challenges water reservoir operations globally, particularly for storage hydropower plants (HPPs), necessitating effective management strategies. One such strategy, fine sediment venting through turbines, though effective in managing sediment continuity, increases hydro-abrasive erosion on turbines due to the additional sediment load. Hence, there is a need for precise real-time monitoring of suspended sediments. Existing systems, however, often lack the capability to measure suspended sediment mass concentration (SSC) and particle size distribution (PSD) with low uncertainty, particularly for coarser particles, such as sand. To maintain particles with sizes up to 2 mm in suspension, which is the size of particles vented through the power waterways of the turbines, this study developed a customized laboratory setup with an upward flow column and a closed pump circuit. To foster a homogeneous SSC distribution, the setup was hydraulically optimized by different diffusor designs at the inlet of the upward flow column. We tested particles ranging from 1500 - 2000 μm at SSCs up to 20 gl−1 with optical and acoustic sensors to prove our concept. First results yielded as expected mostly linear relationships between instrument outputs and nominal SSC, particularly for larger particles. This indicates that the setup allows keeping particles up to 2 mm in suspension, enabling further measurement series to better understand the impacts of sand particles in combination with silt on sensor performance. This is crucial for enhancing suspended sediment monitoring capabilities for fine sediment venting at HPPs.
  • Definitionssache: Turbulenzen, Selbstbelüftung und Wasser-Luft-Abfluss auf Schussrinnen
    Item type: Journal Article
    Friz, Carolin; Bürgler, Matthias; Hohermuth, Benjamin; et al. (2024)
    WasserWirtschaft
    Schussrinnen von Talsperren dienen der sicheren Abführung von Hochwasser. Die typischerweise steilen Neigungen erzeugen schwerkraftbedingt hohe Geschwindigkeiten. An der Gerinnesohle entstehende Turbulenzen führen zu Selbstbelüftung und Wasser-Luft-Abfluss. Das Prozessverständnis ist essenziell zur Bemessung von Schussrinnen. An einem großskaligen Modell wurden mit moderner Messtechnik Experimente durchgeführt. Die Erkenntnisse tragen zum Verständnis hochenergetischer Wasser-Luft-Strömungen und der Dimensionierung von Hochwasserentlastungsanlagen bei.
  • Sediment Venting Through Power Waterways: A Field Monitoring Concept
    Item type: Other Conference Item
    Friz, Carolin; Evers, Frederic M.; Felix, David; et al. (2025)
    Book of Extended Abstracts of the 41st IAHR World Congress – Innovative Water Eng. for Sustainable Development
    Large volumes of sediment are transported annually into hydropower reservoirs, resulting in a reduction of energy storage capacity and impairing the functionality and safety of intake and outlet structures. Given increasing global energy demands, effective sediment management strategies are essential. Current strategies address sedimentation via reduction, removal, or adaptive methods, yet systematic venting of fine sediments through power waterways of hydropower plants remains underexplored. This study develops a monitoring concept for assessing sediment venting. The concept combines a methodology for quantifying hydroabrasion at partly coated Francis turbines with real-time sediment monitoring during venting operations. It includes measurements of the Francis runner coating thickness and referenced laser scans of the installed runner to enable future assessments of local and overall reductions in coating and steel thickness. The concept also incorporates monitoring suspended sediment concentrations over time to find a relation between the sediment load and hydroabrasion. This work aims at fine sediment venting as a countermeasure to reservoir sedimentation and at providing a method to quantify its effects on hydroabrasion in partially coated Francis turbines. Longer-term data collection will allow further insights into how sediment load affects turbine hydroabrasion, supporting sustainable hydropower operation.
Publications 1 - 4 of 4