scholarly journals Experimental Hydraulic Investigation of Angled Fish Protection Systems—Comparison of Circular Bars and Cables

Water ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 1056 ◽  
Author(s):  
Heidi Böttcher ◽  
Roman Gabl ◽  
Markus Aufleger
Keyword(s):  
Power Plants ◽  
Head Loss ◽  
Loss Coefficient ◽  
Guidance System ◽  
Blockage Ratio ◽  
Hydro Power ◽  
Number Range ◽  
Head Loss Coefficient ◽  
Cable Vibrations ◽  
Fish Protection

The requirements for fish protection at hydro power plants have led to a significant decrease of the bar spacing at trash racks as well as the need of an inclined or angled design to improve the guidance effect (fish-friendly trash racks). The flexible fish fence (FFF) is a new developed fish protection and guidance system, created by horizontally arranged steel cables instead of bars. The presented study investigated experimentally the head loss coefficient of an angled horizontal trash rack with circular bars (CBTR) and the FFF with identical cross sections in a flume (scale 1:2). Nine configurations of different bar and cable spacing (blockage ratio) and rack angles were studied for CBTR and FFF considering six different stationary flow conditions. The results demonstrate that head loss coefficient is independent from the studied Bar–Reynolds number range and increases with increasing blockage ratio and angle. At an angle of 30 degrees, a direct comparison between the two different rack options was conducted to investigate the effect of cable vibrations. At the lowest blockage ratio, head loss for both options are in similar very low ranges, while the head loss coefficient of the FFF increases significantly compared to the CBTR with an increase of blockage. Further, the results indicate a moderate overestimation with the predicted head loss by common head loss equations developed for inclined vertical trash racks. Thus, an adaption of the design equation is proposed to improve the estimation of head loss on both rack options.

scholarly journals Effect of the Concentration of Sand in a Mixture of Water and Sand Flowing through PP and PVC Elbows on the Minor Head Loss Coefficient

Water ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 828 ◽  
Author(s):  
Wichowski ◽  
Siwiec ◽  
Kalenik
Keyword(s):  
Reynolds Number ◽  
Cross Sections ◽  
Cross Validation ◽  
Head Loss ◽  
Loss Coefficient ◽  
Number Range ◽  
Head Losses ◽  
Grain Sizes ◽  
Head Loss Coefficient ◽  
The Mathematical Model

The article presents the results of tests of minor head losses through PVC and PP elbows for a flow of water and mixtures of water and sand with grain sizes of up to 0.5 mm and concentrations of 5.6 g·L−1, 10.84 g·L−1, and 15.73 g·L−1. The tests were carried out at variable flow velocities for three elbow diameters of 63 mm, 75 mm, and 90 mm. The flow rate, pressure difference in the tested cross-sections, and temperature of the fluids were measured and automatically recorded. The results of the measurements were used to develop mathematical models for determining the minor head loss coefficient as a function of elbow diameter, sand concentration in the liquid, and Reynolds number. The mathematical model was developed by cross validation. It was shown that when the concentration of sand in the liquid was increased by 1.0 g∙L−1, the coefficient of minor head loss through the elbows increased, in the Reynolds number range of 4.6 × 104–2.1 × 105, by 0.3–0.01% for PP63, 0.6–0.03% for PP75, 1.1–0.06% for PP90, 0.8−0.01% for PVC63, 0.8–0.02% for PVC75, and 0.9–0.04% for PVC90. An increase in Re from 5 × 104 to 2 × 106 for elbows with diameters of 63, 75 and 90 mm caused a 7.3%, 6.8%, and 6.0% decrease in the minor head loss coefficient, respectively.

scholarly journals Effect of the Concentration of Sand in a Mixture of Water and Sand Flowing through PP and PVC Elbows on the Minor Head Loss Coefficient

2019 ◽  
Author(s):  
Piotr Wichowski ◽  
Tadeusz Siwiec ◽  
Marek Kalenik
Keyword(s):  
Reynolds Number ◽  
Cross Sections ◽  
Cross Validation ◽  
Head Loss ◽  
Loss Coefficient ◽  
Number Range ◽  
Head Losses ◽  
Grain Sizes ◽  
Head Loss Coefficient ◽  
The Mathematical Model

The article presents the results of tests of minor head losses through PVC and PP elbows for a flow of water and mixtures of water and sand with grain sizes of up to 0.5 mm and concentrations of 5.6 g∙L-1, 10.84 g∙L-1, and 15.73 g∙L-1. The tests were carried out at variable flow velocities for three elbow diameters of 63, 75, and 90 mm. The flow rate, pressure difference in the tested cross-sections, and temperature of the fluids were measured and automatically recorded. The results of the measurements were used to develop mathematical models for determining the minor head loss coefficient as a function of elbow diameter, sand concentration in the liquid, and Reynolds number. The mathematical model was developed by cross validation. It was shown that when the concentration of sand in the liquid was increased by 1.0 g∙L-1, the coefficient of minor head loss through the elbows increased, in the Reynolds number range of 4.6∙104 − 2.1∙105, by 0.3−0.01% for PP63, 0.6−0.03 % for PP75, 1.1−0.06 % for PP90, 0.8−0.01 % for PVC63, 0.8−0.02 % for PVC75, and 0.9−0.04 % for PVC90. An increase in Re from 5∙104 to 2∙106 for elbows with diameters of 63, 75 and 90 mm caused a 7.3 %, 6.8 %, and 6.0 % decrease in the minor head loss coefficient, respectively.

scholarly journals Head loss coefficient through sharp-edged orifices

2016 ◽  
Vol 49 (6) ◽  
pp. 062009 ◽  
Author(s):  
Nicolas J. Adam ◽  
Giovanni De Cesare ◽  
Anton J. Schleiss ◽  
Sylvain Richard ◽  
Cécile Muench-Alligné
Keyword(s):  
Head Loss ◽  
Loss Coefficient ◽  
Head Loss Coefficient

Study of tunnel outlet head-loss coefficient

2000 ◽  
Vol 27 (6) ◽  
pp. 1306-1310 ◽  
Author(s):  
Minnan Liu ◽  
David Z Zhu
Keyword(s):  
Head Loss ◽  
Loss Coefficient ◽  
Diversion Tunnel ◽  
Head Loss Coefficient

In the design of diversion tunnels, culverts, and pressurized conduits, the outlet head-loss coefficient is generally assumed to be 1.0. However, the head loss can be reduced if a transitional expansion is added to the conduit outlet. This paper studies the reduction in the outlet loss coefficient by using the wingwalls at the tunnel outlet. The best wingwall diffusion angle is found to be 8°, which gives an outlet loss coefficient of 0.62-0.81 with a wingwall length of 2D, with D being the height of the tunnel. A wingwall length of 2D is also found to be suitable, as further increase in length only reduces the outlet loss coefficient marginally. An illustrating example shows that by adding wingwalls of 8° and a length of 2D the headwater level is decreased by 9-22% compared to the case without wingwalls for the same discharge.Key words: outlet, loss coefficient, diversion tunnel, wingwall, diffusion angle.

scholarly journals Experimental Study on Variation Rules of Damping with Influential Factors of Tuned Liquid Column Damper

2017 ◽  
Vol 2017 ◽  
pp. 1-17 ◽  
Author(s):  
Yang Yu ◽  
Lixin Xu ◽  
Liang Zhang
Keyword(s):  
Passive Control ◽  
Uniform Design ◽  
Experimental Studies ◽  
Test System ◽  
Head Loss ◽  
Loss Coefficient ◽  
Liquid Column ◽  
Tuned Liquid Column Damper ◽  
Head Loss Coefficient ◽  
Liquid Column Damper

A tuned liquid column damper (TLCD) is a more effective form of passive control for structural vibration suppression and may be promising for floating platform applications. To achieve good damping effects for a TLCD under actual working conditions, factors that influence the damping characteristics need to be identified. In this study, the relationships between head loss coefficients and other factors such as the total length of the liquid column, opening ratio, Reynolds number, Kc number, and horizontal length of the liquid column were experimentally investigated. By using a hydraulic vibration table, a vibration test system with large-amplitude motion simulation, low-frequency performance, and large stroke force (displacement) control is devised with a simple operation and at low cost. Based on the experimental method of uniform design, a series of experimental studies were conducted to determine the quantitative relationships between the head loss coefficient and other factors. In addition, regression analyses indicated the importance of each factor affecting the head loss coefficient. A rapid design strategy of TLCD head loss coefficient is proposed. This strategy can help people conveniently and efficiently adjust the head loss coefficient to a specified value to effectively suppress vibration.

Sign in / Sign up

Export Citation Format

Share Document