scholarly journals Physical modelling of energy losses at surcharged three-way junction manholes in drainage system

2021 ◽  
Author(s):  
Q. Li ◽  
J. Xia ◽  
M. Zhou ◽  
S. Deng ◽  
H. Zhang ◽  
...  
Keyword(s):  
Energy Loss ◽  
Flow Structure ◽  
Water Depth ◽  
Drainage System ◽  
Physical Modelling ◽  
Head Loss ◽  
Geometrical Parameters ◽  
Flow Discharge ◽  
Discharge Ratio ◽  
Loss Coefficients

Abstract Motivated by the observation that vortex flow structure was evident in the energy loss at the surcharged junction manhole due to changes of hydraulic and geometrical parameters, a physical model was used to calculate energy loss coefficients and investigate the relationship between flow structure and energy loss at the surcharged three-way junction manhole. The effects of the flow discharge ratio, the connected angle between two inflow pipes, the manhole geometry, and the downstream water depth on the energy loss were analyzed based on the quantified energy loss coefficients and the identified flow structure. Moreover, two empirical formulae for head loss coefficients were validated by the experimental data. Results indicate that the effect of flow discharge ratio and connected angle are significant, while the effect of downstream water depth is not obvious. With the increase of the lateral inflow discharge, the flow velocity distribution and vortex structure are both enhanced. It is also found that a circular manhole can reduce local energy loss when compared to a square manhole. In addition, the tested empirical formulae can reproduce the trend of total head loss coefficient.

scholarly journals Energy Loss in Steep Open Channels with Step-Pools

Water ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 72
Author(s):  
Suresh Kumar Thappeta ◽  
S. Murty Bhallamudi ◽  
Venu Chandra ◽  
Peter Fiener ◽  
Abul Basar M. Baki
Keyword(s):  
Energy Loss ◽  
Flow Rate ◽  
Recirculation Zone ◽  
Three Dimensional ◽  
Nonlinear Function ◽  
Open Channels ◽  
Geometrical Parameters ◽  
Transition Flow ◽  
Cumulative Energy ◽  
Zone Velocity

Three-dimensional numerical simulations were performed for different flow rates and various geometrical parameters of step-pools in steep open channels to gain insight into the occurrence of energy loss and its dependence on the flow structure. For a given channel with step-pools, energy loss varied only marginally with increasing flow rate in the nappe and transition flow regimes, while it increased in the skimming regime. Energy loss is positively correlated with the size of the recirculation zone, velocity in the recirculation zone and the vorticity. For the same flow rate, energy loss increased by 31.6% when the horizontal face inclination increased from 2° to 10°, while it decreased by 58.6% when the vertical face inclination increased from 40° to 70°. In a channel with several step-pools, cumulative energy loss is linearly related to the number of step-pools, for nappe and transition flows. However, it is a nonlinear function for skimming flows.

Internal Flow Losses: A Fresh Look at Old Concepts

2011 ◽  
Vol 133 (5) ◽  
Author(s):  
Bastian Schmandt ◽  
Heinz Herwig
Keyword(s):  
Flow Field ◽  
Entropy Generation ◽  
Mechanical Energy ◽  
Internal Flow ◽  
Second Law Of Thermodynamics ◽  
Head Loss ◽  
Local Entropy ◽  
Flow Losses ◽  
Loss Coefficients ◽  
Local Entropy Generation

Losses in a flow field due to single conduit components often are characterized by experimentally determined head loss coefficients K. These coefficients are defined and determined with the pressure as the critical quantity. A thermodynamic definition, given here as an alternative, is closer to the physics of flow losses, however. This definition is based upon the dissipation of mechanical energy as main quantity. With the second law of thermodynamics this dissipation can be linked to the local entropy generation in the flow field. For various conduit components K values are determined and physically interpreted by determining the entropy generation in the component as well as upstream and downstream of it. It turns out that most of the losses occur downstream of the components what carefully has to be taken into account when several components are combined in a flow network.

Effective energy-loss coefficients in the vibration of rod structures

2015 ◽  
Vol 35 (10) ◽  
pp. 737-739
Author(s):  
A. N. Chukarin ◽  
A. P. Sychev ◽  
S. F. Podust
Keyword(s):  
Energy Loss ◽  
Effective Energy ◽  
Loss Coefficients ◽  
Rod Structures

scholarly journals Autogenic influence on the morphology of submarine fans: an approach from 3D physical modelling of turbidity currents

2017 ◽  
Vol 47 (3) ◽  
pp. 345-368
Author(s):  
Cristiano Fick ◽  
Rafael Manica ◽  
Elírio Ernestino Toldo Junior
Keyword(s):  
Deep Water ◽  
Physical Modelling ◽  
Sediment Concentration ◽  
Experimental Series ◽  
Turbidity Currents ◽  
Geometrical Parameters ◽  
Submarine Fans ◽  
Relative Standard ◽  
Length Width ◽  
Depositional Evolution

ABSTRACT: Autogenic controls have significant influence on deep-water fans and depositional lobes morphology. In this work, we aim to investigate autogenic controls on the topography and geometry of deep-water fans. The influence of the sediment concentration of turbidity currents on deep-water fans morphology was also investigated. From the repeatability of 3D physical modeling of turbidity currents, two series of ten experiments were made, one of high-density turbidity currents (HDTC) and another of low-density turbidity currents (LDTC). All other input parameters (discharge, sediment volumetric concentration and grain size median) were kept constant. Each deposit was analyzed from qualitative and quantitative approaches and statistical analysis. In each experimental series, the variability of the morphological parameters (length, width, L/W ratio, centroid, area, topography) of the simulated deep-water fans was observed. Depositional evolution of the HDTC fans was more complex, showing four evolutionary steps and characterized by the self-channelizing of the turbidity current, while LDTC fans neither present self-channelizing, nor evolutionary steps. High disparities on the geometrical parameters of the fans, as characterized by the elevated relative standard deviation, suggest that autogenic controls induced a stochastic morphological behaviour on the simulated fans of the two experimental series.

scholarly journals ADDED MASSES OF LARGE TANKERS BERTHING TO DOLPHINS

1976 ◽  
Vol 1 (15) ◽  
pp. 161 ◽  
Author(s):  
Taizo Hayashi ◽  
Masujiro Shirai
Keyword(s):  
Shallow Water ◽  
Froude Number ◽  
Water Depth ◽  
Head Loss ◽  
Theoretical Formula ◽  
Counter Flow ◽  
Added Masses ◽  
Mass Factor ◽  
Large Vessels ◽  
Good Agreement

The added masses of large tankers berthing to dolphins are studied both theoretically and experimentally. The movements of large vessels in shallow water in the directions normal to their planes of symmetry cause counterflows of appreciable velocities under the hulls. The inertia of these counter-flows is shown to have an important effect on the added masses of the vessels. A theoretical formula is derived to determine the mass factor of an ocean vessel in shallow water as a function of the ratio Draught/Water- depth, the Froude number of the vessel and the coefficient of head loss of the counter-flow under the hull. Experiment is made to determine the mass factor. Comparison:, between the theory and the experiment shows a good agreement.

scholarly journals PERUBAHAN KECEPATAN ALIRAN AKIBAT VARIASI VOLUME VEGETASI DI BELOKAN SALURAN IRIGASI

2019 ◽  
Vol 2 (2) ◽  
pp. 114-122
Author(s):  
Muhammad Nasir ◽  
Eldina Fatimah ◽  
Masimin Masimin
Keyword(s):  
Energy Loss ◽  
Flow Rate ◽  
Water Depth ◽  
Local Community ◽  
Secondary Channel ◽  
Flow Area ◽  
Turn Angle ◽  
Irrigation Network ◽  
Speed Distribution ◽  
North Sumatra

D. I Timbang Deli is 520 Ha of flow area and 5000 meters of secondary channel is located in Deli Serdang Regency, North Sumatra Province. The turn of the irrigation network in overgrown vegetation on the cliffs and bottom of the channel, is expected to reduce the flow rate. The purpose of the study was to see the distribution of velocity, resistance and energy loss in the secondary channel due to vegetation. The method used is conducting surveys in the field by measuring water depth, vegetation volume and flow velocity. Trapezoidal channel with 36 m length, 1.45 lower width, 3.15 m upper width and 33,510 turn angle. The velocity measured in the middle and downstream regions across the channel is divided from points X1 to X5 with Q1 = 0.62m3/ sec and Q2 = 0.83 m3/sec. The results obtained in the speed distribution in Q1 Vmax mean X1 = 0.296 m/s and X5 = 0.199 m/s, the speed decreases due to the turn of 48.82%. On VV3 Vmaks the average is X4 = 0.216 m/sec and (X1 and X2) = 0,000 m/sec, the volocity decreases due to the presence of vegetation between X1, X2 and X5 at Q1 = 100%. In Q2 the average VV0 Vmax condition of the flow X1 = 0.477 m/s and X5 = 0.323 m/s between X1 and X5 the volocity decreases due to turn 28.45%. VV3 Vmax conditions on average X5 = 0.312 m / s and X1 = 0.000 m / s, between X1 and X5 the speed decreases due to the presence of 100% vegetation. In connection with the above results, with this research the local community and local government can carry out cleaning on the channel on a scale basis.

scholarly journals Holistic Design Approach of a Throttled Surge Tank: The Case of Refurbishment of Gondo High-Head Power Plant in Switzerland

Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3440
Author(s):  
Mona Seyfeddine ◽  
Samuel Vorlet ◽  
Nicolas Adam ◽  
Giovanni De Cesare
Keyword(s):  
Power Plant ◽  
Transient Flow ◽  
Holistic Approach ◽  
Head Loss ◽  
Surge Tank ◽  
3D Numerical Modeling ◽  
Head Loss Coefficient ◽  
Loss Coefficients ◽  
High Head ◽  
Modeling Strategy

In order to increase the installed capacity, the refurbishment of Gondo high-head power plant required a modification of the existing surge tank by installing a throttle at its entrance. In a previous study, the geometry of this throttle was optimized by physical modeling to achieve the target loss coefficients as identified by a transient 1D numerical analysis. This study complements previous analyses by means of 3D numerical modeling using the commercial software ANSYS-CFX 19 R1. Results show that: (i) a 3D computational fluid dynamics (CFD) model predicts sufficiently accurate local head loss coefficients that agree closely with the findings of the physical model; (ii) in contrast to a standard surge tank, the presence of an internal gallery in the surge tank proved to be of insignificant effect on a surge tank equipped with a throttle, as the variations in the section of the tank cause negligible local losses compared to the ones induced by the throttle; (iii) CFD investigations of transient flow regimes revealed that the head loss coefficient of the throttle only varies for flow ratios below 20% of the total flow in the system, without significantly affecting the conclusions of the 1D transient analysis with respect to minimum and maximum water level in the surge tank as well as pressure peaks below the surge tank. This study highlights the importance of examining the characteristics of a hydraulic system from a holistic approach involving hybrid modeling (1D, 3D numerical and physical) backed by calibration as well as validation with in-situ measurements. This results in a more rapid and economic design of throttled surge tanks that makes full use of the advantages associated with each modeling strategy.

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