scholarly journals Impact of the Weir Slit Location, the Flow Intensity and the Bed Sand on the Scouring Area and Depth at the Dam Upstream

2021 ◽  
Vol 27 (5) ◽  
pp. 49-62
Author(s):  
Naeem Zayer Al-Hassani ◽  
Thamer Ahmad Mohammad
Keyword(s):  
Geometric Standard Deviation ◽  
Scour Depth ◽  
Flow Rates ◽  
Mobile Bed ◽  
Maximum Value ◽  
Laboratory Flume ◽  
Flow Intensity ◽  
The Impact ◽  
Movable Bed ◽  
Working Section

A total of 48 experiments were conducted to investigate the impact of slit weir dimensions and locations on the maximum scour depth and scour area created upstream. The slit weir model was a 110 mm slit opening, and it was installed at the end of the working section in a laboratory flume. The flume was 10.0 m long, 30 cm wide, 30 cm deep, and almost middle. It includes a 2 m working section with a mobile bed with 110 mm in thickness. In the mobile bed, two types of nonuniform sand (with a geometric standard deviation of 1.58 and 1.6) were tested separately. The weir dimensions and location were changed with flow rates. Then dimensions of the slit weir were changed from 60 x 110 mm to 60 x 70 mm (width x height), while the location of the slit weir was changed from the center of the flume to its side. Finally, the flow rates were changed from 2.6 to 8 l/s. The maximum value of scour depth and scour area was recorded 72 mm and 32357 mm2 when the slit height, the flow rate, D50  of the movable bed were 110 mm, 8 l/s, 0.3 mm, respectively.

scholarly journals Experimental Study of Inclined Bridge Pier Scouring

2020 ◽  
Vol 39 (4) ◽  
pp. 859-870
Author(s):  
Fakhar Muhammad Abbas ◽  
Usman Ali Naeem ◽  
Usman Ghani ◽  
Amina Khan ◽  
Talat Farid Ahmad
Keyword(s):  
Experimental Study ◽  
Inverse Relationship ◽  
Bridge Pier ◽  
Bridge Piers ◽  
Scour Depth ◽  
Clear Water ◽  
Lower Strength ◽  
Flow Rates ◽  
Laboratory Flume ◽  
Horseshoe Vortices

The bridges are one of important structures in any country. The failure of bridges occurs due to many factors including design flaws and manufacturing construction errors. Among all imperfections scouring around the pier is the most detrimental. So, the estimation of local scouring around a bridge pier is of fundamental importance for the safe design of bridges. Although numerous researches have been done on local scouring around a single bridge pier. The present study investigates the effect of angle of inclination of dual bridge pier configuration on local scouring around bridge piers. Principally rectangular shaped dual bridge piers were installed in sand bed of laboratory flume at angle of inclination of 0°,7°,12°,15° and 19° with vertical respectively. Three different flow rates 9, 14 and 18L/sec were considered during each trial. The duration of each trial was kept around 2 hours. The scour depth was measured separately around both piers with the help of point gauge under clear water condition. The value of scour depth around upstream pier was larger as compared to downstream pier because of the lower strength of horseshoe vortices around downstream pier. From the experimental results, it can be concluded that there is an inverse relationship between the angle of inclination and scour depth, an increase in the angle of inclination leads to decrease in scour depth around both piers. The value of scour depth was maximum when piers were at 0° and minimum at 19°. It was also found that scour depth increases with the increase in flow rate.

scholarly journals Land Subsidence Estimation for Aquifer Drainage Induced by Underground Mining

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4658
Author(s):  
Artur Guzy ◽  
Wojciech T. Witkowski
Keyword(s):  
Environmental Impact ◽  
Land Subsidence ◽  
Field Data ◽  
Underground Mining ◽  
Small Scale ◽  
Aquifer System ◽  
Maximum Value ◽  
The Impact ◽  
Method Model ◽  
Impact Of Mining

Land subsidence caused by groundwater withdrawal induced by mining is a relatively unknown phenomenon. This is primarily due to the small scale of such movements compared to the land subsidence caused by deposit extraction. Nonetheless, the environmental impact of drainage-related land subsidence remains underestimated. The research was carried out in the “Bogdanka” coal mine in Poland. First, the historical impact of mining on land subsidence and groundwater head changes was investigated. The outcomes of these studies were used to construct the influence method model. With field data, our model was successfully calibrated and validated. Finally, it was used for land subsidence estimation for 2030. As per the findings, the field of mining exploitation has the greatest land subsidence. In 2014, the maximum value of the phenomenon was 0.313 cm. However, this value will reach 0.364 m by 2030. The spatial extent of land subsidence caused by mining-induced drainage extends up to 20 km beyond the mining area’s boundaries. The presented model provided land subsidence patterns without the need for a complex numerical subsidence model. As a result, the method presented can be effectively used for land subsidence regulation plans considering the impact of mining on the aquifer system.

Study on the Operation Model of Colleges Network Learning Propaganda and Public Opinion Guidance Based on the Internet

2013 ◽  
Vol 380-384 ◽  
pp. 2104-2108
Author(s):  
Chen Liang Li ◽  
Ming Xia Zhu
Keyword(s):  
Public Opinion ◽  
Information Science ◽  
Internet Technology ◽  
The Internet ◽  
C Language ◽  
Network Learning ◽  
Maximum Value ◽  
Network Transmission ◽  
The Impact ◽  
Important Significance

With the development of computer information science and technology, Internet has a large number of network propaganda and public opinion page every day. Through the network micro message and the micro-blog forwarding, network propaganda and public opinion have the impact on the development and stability of colleges, so the study network propaganda and public opinion has important significance for the development of colleges. Under this background, based on the computer Internet technology, the Internet erection of network propaganda guidance mode are analyzed, and compared with the fuzzy minimum production tree theory and the C language software, the network construction is verified. Finally the iterative process of finding the network transmission is relatively stable, after 800 iterative steps, numerical is slowly increasing, in which the maximum value is about 0.0001. The seven school propaganda is been as the minimum spanning of tree main network, its sum of weighted has been up to 1606.

Numerical Investigation of Local Cooling Enhancement Using Pin-Finned Channel With Incremental Impingement

2017 ◽  
Author(s):  
Susheel Singh ◽  
Sumanta Acharya ◽  
Forrest Ames
Keyword(s):  
Aspect Ratio ◽  
Mass Flow ◽  
Cross Flow ◽  
Surface Cooling ◽  
Local Cooling ◽  
Stagnation Region ◽  
Flow Rates ◽  
Pin Fins ◽  
Mass Flow Rates ◽  
The Impact

Flow and heat transfer in a low aspect ratio pin-finned channel, representative of an internally cooled turbine airfoil, is investigated using Large Eddy Simulations (LES). To achieve greater control of surface cooling distribution, a novel approach has been recently proposed in which coolant is injected incrementally through a series of holes located immediately behind a specially designed cutout region downstream of the pin-fins. Sheltering the coolant injection behind the pin-fins avoids the impact of the cross-flow buildup that deflects the impingement jet and isolates the surface from cooling. The longitudinal and transverse spacing of the pin-fins, arranged in a staggered fashion, is X/D = 1.046 and S/D = 1.625, respectively. The aspect ratio (H/D) of pin-fin channel is 0.5. Due to the presence of the sequential jets in the configuration, the local cooling rates can be controlled by controlling the jet-hole diameter which impacts the jet mass flow rate. Hence, four different hole diameters, denoted as Large (L), Medium (M) , Small (S), Petite (P) are tested for impingement holes, and their effects are studied. Several patterns of the hole-size distributions are studied. It is shown that the peak Nusselt number in the stagnation region below the jet correlates directly with the jet-velocity, while downstream the Nusselt numbers correlate with the total mass flow rates or the average channel velocity. The local cooling parameter defined as (Nu/Nu0)(1-ε) correlates with the jet/channel mass flow rates.

scholarly journals Experimental Study of the Debris Flow Slurry Impact and Distribution

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Haixin Zhao ◽  
Lingkan Yao ◽  
Yong You ◽  
Baoliang Wang ◽  
Cong Zhang
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
Impact Force ◽  
Influence Factors ◽  
Flume Experiment ◽  
Middle Point ◽  
Laboratory Flume ◽  
Critical Issues ◽  
Maximum Impact Force ◽  
The Impact

In this study, we present a new method to calculate debris flow slurry impact and its distribution, which are critical issues for designing countermeasures against debris flows. There is no unified formula at present, and we usually design preventive engineering according to the uniform distribution of the maximum impact force. For conducting a laboratory flume experiment, we arrange sensors at different positions on a dam and analyze the differences on debris flow slurry impact against various densities, channel slopes, and dam front angles. Results show that the force of debris flow on the dam distributes unevenly, and that the impact force is large in the middle and decreases gradually to the both sides. We systematically analyze the influence factors for the calculation of the maximum impact force in the middle point and give the quantitative law of decay from the middle to the sides. We propose a method to calculate the distribution of the debris flow impact force on the whole section and provide a case to illustrate this method.

Experimental Analysis of Different Coolants Used in Plasma Cutting Operation for the Improved Electrode Life

2015 ◽  
Vol 719-720 ◽  
pp. 46-49 ◽  
Author(s):  
Ginka Ranga Janardhana ◽  
Mani Senthil Kumar ◽  
B. Dhanasekar
Keyword(s):  
Temperature Rise ◽  
Metal Cutting ◽  
Cooling System ◽  
Heat Removal ◽  
Plasma Cutting ◽  
Life Test ◽  
Flow Rates ◽  
Optimal Flow ◽  
Cutting Operation ◽  
The Impact

The plasma cutting technology has been emerged as a developing technology which finds tremendous potential in fabrication and metal cutting industries. Thus for the cutting operation, the electrode inside the plasma torch plays a vital role for the plasma arc generation. The temperature of the arc is very high and at the electrode is around 3500°C. The cutting torch requires proper cooling system in order to prevent the electrode from quick wear due to the existence of high thermal gradient. The presented work aimed to study the impact of three coolants propylene glycol, ethylene glycol and de-ionized water flow over the electrode life. The experimental setups were arranged to study the heat transfer capabilities of the three coolants for different flow values and aimed to achieve the optimal flow rates for the efficient heat removal. The electrode life test trials were conducted to measure the electrode life for the flow values of three coolants in the temperature rise test. The optimal flow rates arrived from temperature rise test and the electrode life measured from life test are compared for the three coolant cases considered.

Effect of Filler Compositions on the Mechanical Properties of Bamboo Filled Polyester Composite

2014 ◽  
Vol 879 ◽  
pp. 90-95 ◽  
Author(s):  
Abdul Rahman Noor Leha ◽  
Nor Amalina Nordin
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Impact Test ◽  
Compression Molding ◽  
Engineering Applications ◽  
Maximum Value ◽  
Polyester Composite ◽  
Bamboo Powder ◽  
Flexural Tests ◽  
The Impact

Biocomposite from bamboo powder was fabricated by compression molding technique. The objective of this study was to investigate the mechanical properties of bamboo compounded with epoxy with different ratio. Tensile and flexural tests were done to characterize its mechanical properties. It was observed that the strength of bamboo-polyester was increased with increasing amount of bamboo powder. The tensile and flexural strength shows the highest value at 25 wt.% bamboo. However, the impact test shows the maximum value at 20 wt.% bamboo powder. These results exhibit the bamboo-polyester can be a good candidate to be used in many engineering applications

scholarly journals Mathematical Models for Calculation of Mixing Zones for Coastal Effluent Discharges

2019 ◽  
Vol 8 (6S3) ◽  
pp. 97-104
Keyword(s):  
Concentration Level ◽  
Diffusion Equations ◽  
Concentration Limit ◽  
Mixing Zone ◽  
Depth Profiles ◽  
Advection Diffusion ◽  
Maximum Value ◽  
Regulatory Guidelines ◽  
The Impact

The potential long-term environmental impacts of coastal effluent discharges can be addressed and regulated using a mixing zone concept to control and manage the mixing capacity of the receiving coastal waters. The standard regulatory guidelines consist of two key elements: a concentration limit and a point of compliance expressed as a radius centered at the end of the outfall pipe. Modeling studies of the effect of seabed depth upon dispersion of coastal effluent discharges into the sea in the far-field are investigated analytically using the solutions of two-dimensional advection-diffusion equations with a point source on the simple depth profiles of a flat seabed and a uniformly sloping seabed. Solutions are then illustrated graphically by plotting contours of concentration, showing that the effluent discharged plumes are spreading downstream and heading towards the shoreline. Based on the location of maximum value of concentration at the shoreline, the imposed radius of and limit of concentration level within the circular mixing zone are formulated to be used as a measure for assessing the impact of effluent discharges in the coastal environment. The results found agreed with the mixing zones implemented in practice as the environmental quality standards by the regulatory authorities to minimize the impact. As the sea outfall's long pipeline may go beyond the continental shelf, a sudden step change in the seabed depth profiles is introduced, where the solutions of the advection-diffusion equations are obtained using the method of images. An extended formulation of the mixing zones radius and concentration limit are also presented.

scholarly journals Atypical start-up experiments on pump as turbine

2021 ◽  
Vol 13 (11) ◽  
pp. 168781402110627
Author(s):  
Yu-Liang Zhang ◽  
Yan-Juan Zhao
Keyword(s):  
Static Pressure ◽  
Power Coefficient ◽  
Transient Performance ◽  
Test Rig ◽  
Transient Characteristics ◽  
Maximum Value ◽  
Start Up ◽  
Initial Stage ◽  
Evolution Characteristics ◽  
The Impact

At present, research on the characteristics of pumps as turbine (PATs) during the start-up process is still insufficient. To reveal the transient characteristics of a centrifugal PAT during the atypical start-up process, a test rig for the transient performance of the PAT was built; in addition, experiments on the transient hydraulic performance of three kinds of steady speed and three kinds of steady flow were conducted. Through these experiments, the evolution characteristics of the transient performance parameters of the PAT during the atypical start-up process were analyzed over time. Moreover, three dimensionless coefficients were employed to deeply reveal the transient characteristics of the PAT during atypical start-up. Results showed that the rise curves of flow rate and outlet static pressure exhibited shock phenomena. With the increase in the stable running speed after start-up, the impact phenomenon of the outlet static pressure presented a delayed trend. The dimensionless head and flow coefficients reached the maximum value at the initial stage of the atypical start-up process and then rapidly dropped to the minimum value before slowly rising to the final stable value. The dimensionless power coefficient had a maximum value at the initial stage of atypical start-up and then rapidly dropped to the final stable value.

Clear-water local scour at wide piers in shallow-water flow

2014 ◽  
Vol 9 (3) ◽  
pp. 331-343 ◽  
Author(s):  
N. Ahmad ◽  
T. Mohamed ◽  
F. H. Ali ◽  
B. Yusuf
Keyword(s):  
Laboratory Data ◽  
Local Scour ◽  
The Other ◽  
Scour Depth ◽  
Temporal Development ◽  
Clear Water ◽  
Shallow Water Flow ◽  
Equilibrium Time ◽  
Sediment Size ◽  
Flow Intensity

Laboratory data for local scour depth regarding the size of wide piers are presented. Clear water scour tests were performed for various pier widths (0.06, 0.076, 0.102, 0.14 and 0.165 m), two types of pier shapes (circular and rectangular) and two types of uniform cohesionless bed sediment (d50 = 0.23 and d50 = 0.80 mm). New data are presented and used to demonstrate the effects of pier width, pier shape and sediment size on scour depth. The influence of equilibrium time (te) on scouring processes is also discussed. Equilibrium scour depths were found to decrease with increasing values of b/d50. The temporal development of equilibrium local scour depth with new laboratory data is demonstrated for flow intensity V/Vc = 0.95. On the other hand, the results of scour mechanism have shown a significant relationship between normalized volume of scoured and deposited with pier width, b. The experimental data obtained in this study and data available from the literature for wide piers are used to evaluate predictions of existing methods.

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