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 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

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.

scholarly journals Iterative calculation of local head loss coefficient of emitters in lateral lines

2021 ◽  
Vol 25 (5) ◽  
pp. 291-296
Author(s):  
Giuliani Prado ◽  
Rafael R. Bruscagin ◽  
Adriano C. Tinos ◽  
Edmilson C. Bortoletto ◽  
Denise Mahl
Keyword(s):  
Lateral Line ◽  
Pressure Head ◽  
Head Loss ◽  
Loss Coefficient ◽  
Inlet Pressure ◽  
Head Loss Coefficient ◽  
Step Procedure ◽  
Total Head ◽  
Lateral Lines ◽  
Rigid Pvc

ABSTRACT This study aimed to iteratively set the local head loss coefficient of the Naan® micro-sprinkler, model 7110 Hadar, installed in a lateral irrigation line. To evaluate the total head loss along the lateral line, tests were performed using a rigid PVC pipe with an inner diameter of 15.8 mm, 12 m in length, and 24 micro-sprinklers inserted along the pipe, regularly spaced 0.5 m. In the tests carried out for four micro-sprinkler nozzle diameters (0.9, 1.0, 1.1, and 1.2 mm) and six inlet pressure head values (5, 10, 15, 20, 25, and 30 m) in the line, the pressure head difference between inlet and outlet in the pipe and the discharge of each emitter along the pipe were measured. The head loss computation was performed by the step-by-step procedure, starting from the downstream end to the upstream end of the line; since varying the local head loss coefficient values iteratively, the total head loss measured in the tests was equal to the calculated. For the different working conditions of the inlet pressure head and the micro-sprinkler nozzle diameter, the local head loss coefficient had values from 0.051 to 0.169. Relating the discharge values measured and estimated along the lateral line, the confidence coefficient of 0.9991 was verified, and the calculation procedure was considered optimal.

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.

Sign in / Sign up

Export Citation Format

Share Document