scholarly journals Analysis and calculation of sediment scouring rate at different locations of storm sewer

2021 ◽  
Author(s):  
Cuiyun Liu ◽  
Wenke Lv ◽  
Qi Liu ◽  
Jie Zhou ◽  
Yiyang Wang ◽  
...  
Keyword(s):  
Particle Size ◽  
Flow Velocity ◽  
Sediment Thickness ◽  
Water Flow Velocity ◽  
Good Consistency ◽  
Slope Sediment ◽  
Scouring Process ◽  
The Difference ◽  
Front Section ◽  
Storm Sewer

Abstract To explore the migration differences of sediments at the front, middle, and end sections of a storm sewer when scoured by water, and further evaluate the pollution load, the scouring process of sediments at different locations of a storm sewer was simulated and mathematical models were built to calculate the scouring rate. Results show that scouring rate is affected by sediment particle size, pipeline slope, sediment thickness, and water flow velocity. As the slope increased, scouring rate at the end section increased more obviously. The scouring rate at the front section slightly decreased with increasing sediment thickness, but opposite trends were observed at the middle and end sections. When the particle size (0.33 mm–0.83 mm) and flow velocity (0.15 m/s–0.65 m/s) increased within their ranges, scouring rate increased across all three locations. Models for calculating scouring rate were established via two data fitting. The calculated values were compared with measured values at a scouring time of 1 min. Under different particle sizes, the difference between the calculated and measured values at front, middle, and end sections were in the ranges of −0.63% to 0.63%, −0.01% to 0.02%, and −0.13% to 0.16%, respectively, all of which showed good consistency.

scholarly journals Explanation of tuberculation scales formation in steel and iron pipes using the theory of wave motion of a liquid

2018 ◽  
Vol 178 ◽  
pp. 04002
Author(s):  
Alexey Andrianov ◽  
Evgeny Orlov
Keyword(s):  
Flow Velocity ◽  
Water Flow ◽  
Electrochemical Corrosion ◽  
Water Supply Systems ◽  
Water Flow Velocity ◽  
Corrosion Deposits ◽  
The Difference ◽  
Corrosion Of Steel ◽  
Supply Systems ◽  
Turbulent Water

Electrochemical corrosion of steel and iron pipes in water supply systems is a common problem that causes financial losses to operating companies and deteriorates water quality. A comprehensive study of corrosion deposits formation mechanism is necessary for a better understanding of the processes occurring in pipelines and for scientific justification of monitoring and predicting techniques. The influence of various factors (in particular the water flow velocity) on the formation, growth, and spatial distribution of tuberculation scales on the inner surface of pipes is considered. To study the effect of flow velocity, simple serial tests were carried out on segments of a steel non-galvanized pipe in static and dynamic conditions. The difference in the formation of anode and cathode sections in two dynamic modes is recognized. The first stage of tubercle formation is observed. It was assumed that in pipes with turbulent water flow near metal surface, waves forming tubercles are appeared, and the distribution of the tubercles is depend on water flow velocity.

scholarly journals Experiment and fitting calculation of migration critical velocity of small-sized sedaiment particles erosion in rainwater pipeline

2020 ◽  
Author(s):  
Cuiyun Liu ◽  
Yanzhi Chen ◽  
Yuting Yang ◽  
Jingqin Zhou ◽  
Yiyang Wang ◽  
...  
Keyword(s):  
Mathematical Models ◽  
Critical Velocity ◽  
Pipe Wall ◽  
Wall Roughness ◽  
Sediment Thickness ◽  
Good Consistency ◽  
Sediment Particles ◽  
The Difference ◽  
Large Flow ◽  
Strong Erosion

Abstract The migration critical velocity of small-sized sediment particles was investigated through experiments under different particle sizes, pipe wall roughness, and sediment thickness. Such experiments were carried out to simulate the erosion process of small-sized sediment particles in rainwater pipeline during rainfall. The mathematical models were established via quadratic fitting to calculate the critical velocity of migration. Results showed that small particles had powerful cohesive force, and aggregates had strong erosion resistance. So, for the small-sized particles (in the range of 0.33–0.83 mm), the smaller the particle size was, the larger the critical velocity was. When the pipe wall roughness was large, the ‘starting’ particle resistance was high. A large flow dynamic was needed to overcome such resistance. Thus, the critical velocity was great. The critical velocity was also large when the sediment thickness was large. The difference rate between the critical velocity calculated by mathematical models and the measured value was within the range of −3.60% to 5.33% and had good consistency. Under the research conditions, the critical velocity ranges of the four commonly used pipes, namely, plexiglass, steel/PVC, galvanized/clay, and cast iron pipes, were calculated.

Effect of particle size and delignification on the rate of digestion of hemicellulose and cellulose by cellulase in mature pangola grass stems

1983 ◽  
Vol 34 (3) ◽  
pp. 241 ◽  
Author(s):  
CW Ford
Keyword(s):  
Particle Size ◽  
Cell Walls ◽  
Trichoderma Viride ◽  
Structural Features ◽  
Cell Wall Polysaccharides ◽  
Particle Size Reduction ◽  
Digitaria Decumbens ◽  
Hemicellulose Degradation ◽  
Before And After ◽  
The Difference

Stem cell walls of pangola grass (Digitaria decumbens) were ground to two particle sizes (c. 1 and 0.1 mm diameter), and incubated with cellulase (ex. Trichoderma viride) for varying times before and after delignification. Total cell walls finely ground (0.1 mm) with a Spex Shatterbox mill were initially degraded more rapidly (to 24 h) than delignified 1 mm particles. Thereafter the delignified material was solubilized to a greater extent. Subsequent specific determinations of cell wall polysaccharides indicated that delignification increased the rate of hemicellulose degradation to a greater extent than did particle size reduction, whereas the opposite was found for cellulose. The difference between delignified and Spex-ground residues, in terms of the amount of polysaccharide digested, was much greater for cellulose than hemicellulose. It is concluded that structural features play a more important role in limiting cellulase degradation of cellulose than does association with lignin, the reverse being so for hemicellulose.

Experimental Study on Hydraulic Roughness of Submerged Grass in Ecological Riverbank

2013 ◽  
Vol 838-841 ◽  
pp. 1743-1748
Author(s):  
Dian Guang Ma ◽  
Chun Xin Zhong ◽  
Wu Ning ◽  
Qing Ye ◽  
Sheng Zhu
Keyword(s):  
Flow Velocity ◽  
Roughness Coefficient ◽  
Theoretic Analysis ◽  
Mean Flow ◽  
Normal Range ◽  
Obvious Effect ◽  
Hydraulic Roughness ◽  
Natural Turf ◽  
Scouring Process ◽  
The Mean

A model experiment about the hydraulic roughness of natural turf used in riverbank was carried out in flume. To examine the rationality of experimental design, the hydraulic roughness coefficient of plexiglass-flume was tested firstly. The result was 0.0085, which is quite normal. Then the tested hydraulic roughness caused by vegetation ranges from 0.020 to 0.090 for the chosen plants, which is also acceptable. Furthermore, the tested incipient velocities of krasnozem, and paddysoil had the range of 0.55~0.65m·s-1 and 1.0~1.1m·s-1, respectively. All these experimental results are in normal range, which means that the design of this experimental is rational. Experimental research illustrate that, the roughness coefficient of plant reduces with the increasing of flow velocity. When the mean flow velocity is over 3m·s-1, Mannings n values vary between 0.025 and 0.035. This phenomenon is accord with the theoretic analysis. During the scouring process, not only the flow velocity, but also the flow duration has an obvious effect on the coarseness of vegetative bed.

Production of quicklime from Ashaka limestone through calcination process

2021 ◽  
Vol 1 (2) ◽  
pp. 041-048
Author(s):  
Benson Chinweuba Udeh
Keyword(s):  
Particle Size ◽  
Critical Value ◽  
Operating Conditions ◽  
Quadratic Model ◽  
Particle Sizes ◽  
Calcination Process ◽  
Process Effects ◽  
Effects Of Temperature ◽  
The Difference ◽  
The Relationship

This study is on the production of quicklime from Ashaka limestone through calcination process. Effects of temperature, particle size and time on quicklime yield were determined. The experiment was carried out at temperatures of 800, 900, 1000, 1100 and 1200 0C, particle sizes of 80mm, 90mm, 100mm, 300mm and 425mm and times of 0.5hr, 1hr, 2hrs, 3hrs and 4hrs. Analyses of the results showed that quicklime was successfully produced from Ashaka limestone through the calcination process. Quadratic model adequately described the relationship between quicklime yield and calcination factors of temperature, particle size and time. Recorded model F-value of 134.35 implies that the model is significant. The predicted R² of 0.9597 is in reasonable agreement with the adjusted R² of 0.9844; the difference is less than the critical value of 0.2. Optimum yield of 73.48% was obtained at optima operating conditions; temperature of 1000 0C, particle size of 90 µm and time of 3 hrs.

Producing Steam by Spraying Water on a Heated Bed of Steel Spheres

2021 ◽  
pp. 1-42
Author(s):  
D. Jordan Bouchard ◽  
HengSheng Yang ◽  
Sanjeev Chandra
Keyword(s):  
Particle Size ◽  
Thermal Mass ◽  
Steam Generation ◽  
Bed Porosity ◽  
The Media ◽  
Effect Of Particle Size ◽  
The Difference ◽  
Rate Of Evaporation ◽  
A Minor ◽  
Counter Current

Abstract Steam generators used in industrial baking ovens operate by pouring or spraying water on a preheated thermal mass. This paper presents a methodology to quantify the amount of steam generated from a thermal mass along with experiments to determine the effect of particle size and porosity on steam generation. Three sizes of steel spheres, 0.6 mm, 8 mm, and 16 mm in diameter, were used to construct porous media beds that were preheated in an oven after which water was sprayed onto them from a full-cone nozzle for a fixed duration. The weight of the heated bed and the impinging water were recorded during spraying. The difference in weight change when spraying on heated and unheated beds gave the rate of evaporation. Thermocouples were used to record the internal temperature of the bed. Steam generation rate increased with particle size while bed porosity had only a minor influence. The counter-current flow of steam within the media bed disrupts the downward flow of water enough to leave pockets of hot material, reducing steam production. To maximize steam generation the media size, material, and spray time should be matched to ensure the surfaces of particles remain above the boiling point of water during spraying.

The effects of changing water flow velocity on the formation of biofilms and water quality in pilot distribution system consisting of copper or polyethylene pipes

2006 ◽  
Vol 40 (11) ◽  
pp. 2151-2160 ◽  
Author(s):  
Markku J. Lehtola ◽  
Michaela Laxander ◽  
Ilkka T. Miettinen ◽  
Arja Hirvonen ◽  
Terttu Vartiainen ◽  
...  
Keyword(s):  
Water Quality ◽  
Flow Velocity ◽  
Water Flow ◽  
Distribution System ◽  
Water Flow Velocity ◽  
Polyethylene Pipes

scholarly journals MINERAL ABUNDANCE AND PARTICLE SIZE DISTRIBUTION DERIVED FROM IN-SITU SPECTRA MEASUREMENTS OF YUTU ROVER OF CHANG’E-3

2017 ◽  
Vol XLII-3/W1 ◽  
pp. 85-89
Author(s):  
H. Lin ◽  
X. Zhang ◽  
Y. Yang ◽  
X. Wu ◽  
D. Guo
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Landing Site ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Particle Sizes ◽  
The Mean ◽  
The Difference ◽  
Yutu Rover

From geologic perspective, understanding the types, abundance, and size distributions of minerals allows us to address what geologic processes have been active on the lunar and planetary surface. The imaging spectrometer which was carried by the Yutu Rover of Chinese Chang’E-3 mission collected the reflectance at four different sites at the height of ~ 1 m, providing a new insight to understand the lunar surface. The mineral composition and Particle Size Distribution (PSD) of these four sites were derived in this study using a Radiative Transfer Model (RTM) and Sparse Unmixing (SU) algorithm. The endmembers used were clinopyroxene, orthopyroxene, olivine, plagioclase and agglutinate collected from the lunar sample spectral dataset in RELAB. The results show that the agglutinate, clinopyroxene and olivine are the dominant minerals around the landing site. In location Node E, the abundance of agglutinate can reach up to 70 %, and the abundances of clinopyroxene and olivine are around 10 %. The mean particle sizes and the deviations of these endmembers were retrieved. PSDs of all these endmembers are close to normal distribution, and differences exist in the mean particle sizes, indicating the difference of space weathering rate of these endmembers.

Sign in / Sign up

Export Citation Format

Share Document