The Experts below are selected from a list of 153 Experts worldwide ranked by ideXlab platform
Dennis D Dauble - One of the best experts on this subject based on the ideXlab platform.
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evaluation of blade strike models for estimating the biological performance of Kaplan Turbines
Ecological Modelling, 2007Co-Authors: Zhiqun Deng, Thomas J Carlson, Gene R Ploskey, Marshall C Richmond, Dennis D DaubleAbstract:Bio-indexing of hydro Turbines is an important means to optimize passage conditions for fish by identifying operations for existing and new design Turbines that minimize the probability of injury. Cost-effective implementation of bio-indexing requires the use of tools such as numerical and physical turbine models to generate hypotheses for turbine operations that can be tested at prototype scales using live fish. Numerical deterministic and stochastic blade-strike models were developed for a 1:25-scale physical turbine model built by the U.S. Army Corps of Engineers for the original design turbine at McNary Dam and for prototype-scale original design and replacement minimum gap runner (MGR) Turbines at Bonneville Dam’s first powerhouse. Blade-strike probabilities predicted by both models were comparable with those observed in both prototype-scale live fish survival studies and a physical turbine model using neutrally buoyant beads. Predictions from the stochastic model were closer to experimental data than predictions from the deterministic model because the stochastic model considered the aspects of fish approaching to the leading edges of turbine runner blades. Therefore, the stochastic model should be the preferred method for the prediction of blade strike and injury probability for juvenile salmon and steelhead using numerical blade-strike models for evaluating the biological performance of Kaplan hydro Turbines.
Zhengwei Wang - One of the best experts on this subject based on the ideXlab platform.
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Fatigue Analysis of the Piston Rod in a Kaplan Turbine Based on Crack Propagation under Unsteady Hydraulic Loads
IOP Conference Series: Earth and Environmental Science, 2014Co-Authors: Zhengwei WangAbstract:As an important component of the blade-control system in Kaplan Turbines, piston rods are subjected to fluctuating forces transferred by the Turbines blades from hydraulic pressure oscillations. Damage due to unsteady hydraulic loads might generate unexpected down time and high repair cost. In one running hydropower plant, the fracture failure of the piston rod was found twice at the same location. With the transient dynamic analysis, the retainer ring structure of the piston rod existed a relative high stress concentration. This predicted position of the stress concentration agreed well with the actual fracture position in the plant. However, the local strain approach was not able to explain why this position broke frequently. Since traditional structural fatigue analyses use a local stress strain approach to assess structural integrity, do not consider the effect of flaws which can significantly degrade structural life. Using linear elastic fracture mechanism (LEFM) approaches that include the effect of flaws is becoming common practice in many industries. In this research, a case involving a small semi-ellipse crack was taken into account at the stress concentration area, crack growth progress was calculated by FEM. The relationship between crack length and remaining life was obtained. The crack propagation path approximately agreed with the actual fracture section. The results showed that presence of the crack had significantly changed the local stress and strain distributions of the piston rod compared with non-flaw assumption.
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Computation of dynamic stresses in piston rods caused by unsteady hydraulic loads
Engineering Failure Analysis, 2007Co-Authors: Zhengwei Wang, Lingjiu Zhou, Ruofu Xiao, Guangjie PengAbstract:Abstract The stresses in piston rods, a very important part of the blade-control system in Kaplan Turbines, were analyzed to predict failure conditions. The turbine blades suffer from pressure oscillations whose forces are transferred to the piston rods. The 3D unsteady flow through the Kaplan turbine was simulated to predict the forces on the piston rod. The unsteady Reynolds-averaged Navier–Stokes (RANS) equations with the SST κ – ω turbulence model were solved to model the flow within the entire flow path of the Kaplan turbine. The unsteady hydraulic forces on the blades were then used as the boundary condition for dynamic analysis of piston rods either fixed with a nut or fixed with a retainer ring for various operating conditions. The results show that the mean stress and the dynamic stress for the nut structure were less than for the retainer ring structure because the nut structure had a pretightening force. The dynamic stress with the retainer ring structure reached 23.7 MPa at the high head low output condition with a very low safety coefficient, which caused the final breakage of the rod. The predicted stress concentration position in the rod agreed well with the fracture position.
Zhiqun Deng - One of the best experts on this subject based on the ideXlab platform.
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evaluation of blade strike models for estimating the biological performance of Kaplan Turbines
Ecological Modelling, 2007Co-Authors: Zhiqun Deng, Thomas J Carlson, Gene R Ploskey, Marshall C Richmond, Dennis D DaubleAbstract:Bio-indexing of hydro Turbines is an important means to optimize passage conditions for fish by identifying operations for existing and new design Turbines that minimize the probability of injury. Cost-effective implementation of bio-indexing requires the use of tools such as numerical and physical turbine models to generate hypotheses for turbine operations that can be tested at prototype scales using live fish. Numerical deterministic and stochastic blade-strike models were developed for a 1:25-scale physical turbine model built by the U.S. Army Corps of Engineers for the original design turbine at McNary Dam and for prototype-scale original design and replacement minimum gap runner (MGR) Turbines at Bonneville Dam’s first powerhouse. Blade-strike probabilities predicted by both models were comparable with those observed in both prototype-scale live fish survival studies and a physical turbine model using neutrally buoyant beads. Predictions from the stochastic model were closer to experimental data than predictions from the deterministic model because the stochastic model considered the aspects of fish approaching to the leading edges of turbine runner blades. Therefore, the stochastic model should be the preferred method for the prediction of blade strike and injury probability for juvenile salmon and steelhead using numerical blade-strike models for evaluating the biological performance of Kaplan hydro Turbines.
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evaluation of blade strike models for estimating the biological performance of large Kaplan hydro Turbines
2005Co-Authors: Zhiqun Deng, Thomas J Carlson, Gene R Ploskey, Marshall C RichmondAbstract:Bio-indexing of hydro Turbines has been identified as an important means to optimize passage conditions for fish by identifying operations for existing and new design Turbines that minimize the probability of injury. Cost-effective implementation of bio-indexing requires the use of tools such as numerical and physical turbine models to generate hypotheses for turbine operations that can be tested at prototype scales using live fish. Blade strike has been proposed as an index variable for the biological performance of Turbines. Report reviews an evaluation of the use of numerical blade-strike models as a means with which to predict the probability of blade strike and injury of juvenile salmon smolt passing through large Kaplan Turbines on the mainstem Columbia River.
K Amini - One of the best experts on this subject based on the ideXlab platform.
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numerical investigations on swirl intensity decay rate for turbulent swirling flow in a fixed pipe
International Journal of Mechanical Sciences, 2011Co-Authors: A F Najafi, S M Mousavian, K AminiAbstract:Abstract Due to the importance of predicting the SIDR 1 associated with engineering problems such as combustion chambers, draft tube of the Francis and Kaplan Turbines, heat exchanger tubes, separators and so forth, in this research the trend of SIDR and its affecting factors, through a turbulent swirl decay pipe flow have been investigated. The swirling flow is created by means of a rotating honeycomb which produces solid body rotation at the inlet of a fixed pipe. First of all, turbulent swirling decay flow has been numerically surveyed using different flow conditions at the pipe inlet. The numerical results have been validated and compared with the existing experimental data and mathematical relations, showing satisfactory coincide. The obtained results show that, the SIDR depends mainly on the Reynolds number of the passing flow. On this basis, correlations have been proposed in order to improve the predictions of swirl intensity decay rate at upstream regions as well as those with high swirl intensity. In addition, conducted analyses demonstrates (analyses have been made to demonstrate) that the previous developed correlations for predicting swirl intensity decay rate, agree with those provided in this study only for regions far enough from downstream having the low swirl intensity. This implies that the swirl intensity decay rate should be a function of the type of swirl generator at the pipe inlet.
Marshall C Richmond - One of the best experts on this subject based on the ideXlab platform.
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evaluation of blade strike models for estimating the biological performance of Kaplan Turbines
Ecological Modelling, 2007Co-Authors: Zhiqun Deng, Thomas J Carlson, Gene R Ploskey, Marshall C Richmond, Dennis D DaubleAbstract:Bio-indexing of hydro Turbines is an important means to optimize passage conditions for fish by identifying operations for existing and new design Turbines that minimize the probability of injury. Cost-effective implementation of bio-indexing requires the use of tools such as numerical and physical turbine models to generate hypotheses for turbine operations that can be tested at prototype scales using live fish. Numerical deterministic and stochastic blade-strike models were developed for a 1:25-scale physical turbine model built by the U.S. Army Corps of Engineers for the original design turbine at McNary Dam and for prototype-scale original design and replacement minimum gap runner (MGR) Turbines at Bonneville Dam’s first powerhouse. Blade-strike probabilities predicted by both models were comparable with those observed in both prototype-scale live fish survival studies and a physical turbine model using neutrally buoyant beads. Predictions from the stochastic model were closer to experimental data than predictions from the deterministic model because the stochastic model considered the aspects of fish approaching to the leading edges of turbine runner blades. Therefore, the stochastic model should be the preferred method for the prediction of blade strike and injury probability for juvenile salmon and steelhead using numerical blade-strike models for evaluating the biological performance of Kaplan hydro Turbines.
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evaluation of blade strike models for estimating the biological performance of large Kaplan hydro Turbines
2005Co-Authors: Zhiqun Deng, Thomas J Carlson, Gene R Ploskey, Marshall C RichmondAbstract:Bio-indexing of hydro Turbines has been identified as an important means to optimize passage conditions for fish by identifying operations for existing and new design Turbines that minimize the probability of injury. Cost-effective implementation of bio-indexing requires the use of tools such as numerical and physical turbine models to generate hypotheses for turbine operations that can be tested at prototype scales using live fish. Blade strike has been proposed as an index variable for the biological performance of Turbines. Report reviews an evaluation of the use of numerical blade-strike models as a means with which to predict the probability of blade strike and injury of juvenile salmon smolt passing through large Kaplan Turbines on the mainstem Columbia River.
