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Characterization of Suspended Frazil and Surface Ice in Rivers Using SonarsGhobrial, Tadros I.R. Unknown Date
No description available.
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A mathematical and experimental study of anchor iceQu, Yuexia 13 October 2010 (has links)
The existence of anchor ice in supercooled water can have a profound impact on the
management of water resource infrastructures in cold regions. For example, it can raise a
tailrace water level and cause significant losses in generation revenue. So far, there have
been limited studies on anchor ice, therefore, many problems still exist and much more
study is needed. In the present research, experimental and mathematical studies of
anchor ice were carried out.
Experiments were conducted in a counter-rotating flume, located in a cold room at the
University of Manitoba. The experiments were mainly focused on anchor ice evolution
around rocks and on gravel beds under different hydro-meteorological conditions. The
results are compared to a mathematical model developed herein and some important
parameters such as anchor ice porosity and frazil ice deposition coefficient are examined.
The growth process of anchor ice was monitored by two CCD cameras. A digital
processing program was developed to analyze anchor ice images and determine the
growth rate of anchor ice. In addition, anchor ice density, an important factor when
studying anchor ice, was estimated and the effect of air temperature, Froude number and
Reynolds number is explored. By analyzing torque load signals from the counter-rotating
flume, the variation of bed roughness with the growth of anchor ice is elucidated. The
deposition coefficient of anchor ice growth was also determined from the experiments.
A mathematical model was developed based on a two-stage method to simulate the
process of frazil ice transportation and deposition. Both frazil ice attachment and heat
transfer between the supercooled water and ice crystals are considered in the model. Four
governing equations related to the distribution of velocity and frazil ice transportation and
deposition inside and outside the roughness layers were built. A fourth-order Runge-
Kutta numerical method was used and programmed in Matlab to solve the governing
equations. The growth rate of anchor ice under different hydro-meteorological conditions
can be simulated by this numerical model.
The proposed experimental and mathematical studies of anchor ice are presented
intuitively in this paper and the results from this study contribute to a better
understanding of the anchor ice growth mechanism. This study will help to develop
better management strategies to mitigate ice related complications associated with
hydroelectric generating stations and other hydraulic structures in cold regions.
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A mathematical and experimental study of anchor iceQu, Yuexia 13 October 2010 (has links)
The existence of anchor ice in supercooled water can have a profound impact on the
management of water resource infrastructures in cold regions. For example, it can raise a
tailrace water level and cause significant losses in generation revenue. So far, there have
been limited studies on anchor ice, therefore, many problems still exist and much more
study is needed. In the present research, experimental and mathematical studies of
anchor ice were carried out.
Experiments were conducted in a counter-rotating flume, located in a cold room at the
University of Manitoba. The experiments were mainly focused on anchor ice evolution
around rocks and on gravel beds under different hydro-meteorological conditions. The
results are compared to a mathematical model developed herein and some important
parameters such as anchor ice porosity and frazil ice deposition coefficient are examined.
The growth process of anchor ice was monitored by two CCD cameras. A digital
processing program was developed to analyze anchor ice images and determine the
growth rate of anchor ice. In addition, anchor ice density, an important factor when
studying anchor ice, was estimated and the effect of air temperature, Froude number and
Reynolds number is explored. By analyzing torque load signals from the counter-rotating
flume, the variation of bed roughness with the growth of anchor ice is elucidated. The
deposition coefficient of anchor ice growth was also determined from the experiments.
A mathematical model was developed based on a two-stage method to simulate the
process of frazil ice transportation and deposition. Both frazil ice attachment and heat
transfer between the supercooled water and ice crystals are considered in the model. Four
governing equations related to the distribution of velocity and frazil ice transportation and
deposition inside and outside the roughness layers were built. A fourth-order Runge-
Kutta numerical method was used and programmed in Matlab to solve the governing
equations. The growth rate of anchor ice under different hydro-meteorological conditions
can be simulated by this numerical model.
The proposed experimental and mathematical studies of anchor ice are presented
intuitively in this paper and the results from this study contribute to a better
understanding of the anchor ice growth mechanism. This study will help to develop
better management strategies to mitigate ice related complications associated with
hydroelectric generating stations and other hydraulic structures in cold regions.
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Detection of Frazil Ice at Water Intakes at Träbena Power StationCarrera Artola, Iosu, Lucena Garcerán, Alejandro January 2014 (has links)
Frazil ice is a phenomenon that takes place in cold regions when the water of rivers, lakes or oceans is cooled under 0ºC. Several times during winter, frazil ice can appear at river Ätran, where Träbena hydropower plant is held by the company Wetterstad Consulting AB. Frazil ice particles contained in the flowing water are extremely sticky and adhere to any object placed in the water. Trash racks are used by the power plant at the water intakes to prevent any strange object to go into the turbines. However, frazil ice particles stick to the trash racks creating an ice blockage that interrupts the water inflow. In this situation, the power plant has to stop the production even for several months, due to the lack of water that reaches the turbines. In order to solve this problem, the company has installed a heating system on the trash racks that prevent the adhesion of frazil ice particles. This system is manually operated, and it is turned on or off based on the experience and predictions of the company. This heating system is very power consuming and every time it is turned on unnecessarily the company loses money. An automatic frazil ice detection system that turns on the heating system when needed is to be created. For that, several options have been analysed, and finally a capacitor-based sensor has been developed as a solution. The sensor consist of two steel plates coated with semi-transparent polycarbonate submerged underwater parallel placed in the space between the trash racks’ bars, forming this way a parallel plate capacitor. The capacitance of a capacitor depends exclusively on its geometry and the dielectric material between the plates. Hence when the water temperature is low enough, frazil ice particles stick to the plates of the capacitor and its capacitance will vary indicating that the accretion of frazil ice may block the water inflow. This variation is registered and a signal is send to the heating system to start operating. This way, the heating system is completely automated; no human intervention is needed at all. / <p>Developed for Wettestad Consulting AB.</p>
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När bildas is? : En studie om ispredicering och faktorer som påverkar isbildning / When does ice form? : A study about ice-prediction and factors affecting ice-growth.Berglund, Dennis January 2023 (has links)
An improved knowledge regarding what spatial scale temperature data is needed for ice-prediction would improve calculations how ice-coverage has been affected over time. Which by extension would give insight how ice might response to climate change. The purpose of this study was to find out if ice-growth in Sävar River could be explained by both local and regional temperature data, and what factors beyond temperature affect ice-growth. To accomplish this, I analyzed time-lapse photos from Sävar River during a three-month period. I found out that the use of regional temperature data to explain ice-growth on a local scale is limited due to the differences in accumulated degrees. The local temperature data measurement accumulated -2281 °C from ice began to grow until the whole channel was ice-covered and the regional temperature data accumulated -1901 °C under the same period. My findings support the assumption that frazil ice in large concentrations seem to increase ice-growth. Furthermore, no relation between ice-growth/decrease and precipitation or wet spots was found in this study.
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