In this article, the unified mathematical model for splash droplets and suspended mist of atomized flow was established, which classifies the atomized sources into the splash source and the suspended source. For the s...In this article, the unified mathematical model for splash droplets and suspended mist of atomized flow was established, which classifies the atomized sources into the splash source and the suspended source. For the splash source, the Lagrangian method was used to simulate the random motion of splash water droplets, and for the suspended source the theory of air-water two-phase flow was used to simulate the mist flow moving in particle clouds. The rainfall intensity of the atomized flow was obtained by summarizing the rainfall intensities relative to the above two types of atomized sources. Both experimental data and prototype observation data were used for the verification of the mathematical model. For both the distribution of rainfall intensity, and the outer edge of the atomized flow, the simulation results are in agreement with the experimental data or prototype observation data.展开更多
This study evaluated the morphological characteristics and dynamic variation in characteristics of soil crust and iden-tified the relationships between soil crust and splash erosion under simulated rainfall.The effect...This study evaluated the morphological characteristics and dynamic variation in characteristics of soil crust and iden-tified the relationships between soil crust and splash erosion under simulated rainfall.The effect of polyacrylamide (PAM) on soil aggregate stabilization and crust formation was also investigated.A laboratory rainfall simulation experiment was carried out using soil sample slices.The slices were examined under a polarized light microscopy and a scanning electron microscope (SEM).The results revealed that the soil crusts were thin and were characterized by a greater density,higher shear strength,finer porosity,and lower saturated hydraulic conductivity than the underlying soil.Two types of crusts,i.e.,structural and depositional crusts,were observed.Soil texture was determined to be the most important soil variable influ-encing surface crust formation;depositional crust formation was primarily related to the skeleton characteristics of the soil and happened when the soil contained a high level of medium and large aggregates.The crust formation processes observed were as follows:1) The fine particles on the soil surface became spattered,leached,and then rough in response to raindrop impact and 2) the fine particles were washed into the subsoil pores while a compact dense layer concurrently formed at soil surface due to the continual compaction by the raindrops.Therefore,the factors that influenced structural crust formation were a large amount of fine particles in the soil surface,continual impact of raindrops,dispersion of aggregates into fine particles,and the formation of a compact dense layer concurrently at the soil surface.It was concluded that the most important factor in the formation of soil crusts was raindrop impact.When polyacrylamide (PAM) was applied,it restored the soil structure and greatly increased soil aggregate stabilization.This effectively prevented crust formation.However,this function of PAM was not continuously effective and the crust reformed with long-term rainfall.In co展开更多
Experiments were designed to simulate the corrosion of a low-carbon steel exposed to a marine splash zone. The composition and morphology of the rust were investigated using Raman spectroscopy, X-ray photoelectron spe...Experiments were designed to simulate the corrosion of a low-carbon steel exposed to a marine splash zone. The composition and morphology of the rust were investigated using Raman spectroscopy, X-ray photoelectron spectroscopy, energy-dispersive spectrometry and scanning electron microscopy. Corrosion resistance of the rust films was demonstrated by the electrochemical impedance spectroscopy. The wettability of the steel surface was calculated from the data conceruing the wetting degree and the conductivity. The results showed that, in the initial stage, the products of the outer rust layer were mainly made up of Fe（Ⅲ） oxyhydroxide, while the main component of the inner rust layer was magnetite. With an increase in the corrosion time, the inner rust layer continuously turned into the outer rust layer. In addition, both rust layers became dense, thus playing a protective role with respect to matrix. The existence of the rust layer significantly prolonged the residence time of the seawater on the sample surface, a result that tends to improve the cathodic protection effect for steel structures exposed to marine splash zones.展开更多
Effective soil particle size composition can more realistically reflect the particle size sorting process of erosion.To reveal the individual contributions of rainfall intensity and slope to splash erosion,and to dist...Effective soil particle size composition can more realistically reflect the particle size sorting process of erosion.To reveal the individual contributions of rainfall intensity and slope to splash erosion,and to distinguish the enrichment ratio of each size and the critical size in splash,loessial soil collected on the Loess Plateau in May 2019 was tested under different rainfall intensities(60,84,108,132,156 mm h^(-1))and slopes(0°,5°,10°,15°,20°).The results demonstrated that 99%of splash mass was concentrated in 0–0.4 m.Rainfall intensity was the major factor for splash according to the raindrop generation mode by rainfall simulator nozzles.The contributions of rainfall intensity to splash erosion were 82.72%and 93.24%,respectively in upslope and downslope direction.The mass percentages of effective clay and effective silt were positively correlated with rainfall intensity,while the mass percentages of effective very fine sand and effective fine sand were negatively correlated with rainfall intensity.Opposite to effective very fine sand,the mass percentages of effective clay significantly decreased with increasing distance.Rainfall intensity had significant effects on enrichment ratios,positively for effective clay and effective silt and negatively for effective very fine sand and effective fine sand.The critical effective particle size in splash for loessial soil was 50μm.展开更多
Atomized flow is an unnatural two-phase flow produced while water discharges in water release structures. This flow might threaten the normal operation of hydraulic and hydroelectric installations owing to the unnatur...Atomized flow is an unnatural two-phase flow produced while water discharges in water release structures. This flow might threaten the normal operation of hydraulic and hydroelectric installations owing to the unnatural and high-density rain as well as the unnatural and dirty mist. The splash region, the region with the highest rain intensity, hence should receive much attention during the design and operation of the hydraulic and hydroelectric installations. In this paper rain intensity distribution in the splash region of the atomized flow is investigated experimentally, and the method of random simulation is used to predict the rain intensity distribution in the splash region.展开更多
This study determined that the range of the marine splash zone (MSZ) of China’s Qingdao,Zhoushan. Xiamen. Zhanjiang harbour area was about 0-2.4 m above the mean high water level (MHWL) of the seawater that the MSZ c...This study determined that the range of the marine splash zone (MSZ) of China’s Qingdao,Zhoushan. Xiamen. Zhanjiang harbour area was about 0-2.4 m above the mean high water level (MHWL) of the seawater that the MSZ corrosion peak (MSZCP) was usually 0.6- 1.2 m above the MHWL. and was caused by the large salt particle accumulation on the A3 carbon steel test sample surface and by the high frequency altemations of wet and dry environmental conditions around the samples.展开更多
基金the National Natural Science Foundation of China (Grant No. 50539060).
文摘In this article, the unified mathematical model for splash droplets and suspended mist of atomized flow was established, which classifies the atomized sources into the splash source and the suspended source. For the splash source, the Lagrangian method was used to simulate the random motion of splash water droplets, and for the suspended source the theory of air-water two-phase flow was used to simulate the mist flow moving in particle clouds. The rainfall intensity of the atomized flow was obtained by summarizing the rainfall intensities relative to the above two types of atomized sources. Both experimental data and prototype observation data were used for the verification of the mathematical model. For both the distribution of rainfall intensity, and the outer edge of the atomized flow, the simulation results are in agreement with the experimental data or prototype observation data.
基金Supported by the National Natural Science Foundation of China (NSFC) (No. 41101019)the Fundamental Research Funds for the Central Universities of Chinathe State Key Laboratory of Earth Surface Processes and Resource Ecology of China (No. 2011-KF-09)
文摘This study evaluated the morphological characteristics and dynamic variation in characteristics of soil crust and iden-tified the relationships between soil crust and splash erosion under simulated rainfall.The effect of polyacrylamide (PAM) on soil aggregate stabilization and crust formation was also investigated.A laboratory rainfall simulation experiment was carried out using soil sample slices.The slices were examined under a polarized light microscopy and a scanning electron microscope (SEM).The results revealed that the soil crusts were thin and were characterized by a greater density,higher shear strength,finer porosity,and lower saturated hydraulic conductivity than the underlying soil.Two types of crusts,i.e.,structural and depositional crusts,were observed.Soil texture was determined to be the most important soil variable influ-encing surface crust formation;depositional crust formation was primarily related to the skeleton characteristics of the soil and happened when the soil contained a high level of medium and large aggregates.The crust formation processes observed were as follows:1) The fine particles on the soil surface became spattered,leached,and then rough in response to raindrop impact and 2) the fine particles were washed into the subsoil pores while a compact dense layer concurrently formed at soil surface due to the continual compaction by the raindrops.Therefore,the factors that influenced structural crust formation were a large amount of fine particles in the soil surface,continual impact of raindrops,dispersion of aggregates into fine particles,and the formation of a compact dense layer concurrently at the soil surface.It was concluded that the most important factor in the formation of soil crusts was raindrop impact.When polyacrylamide (PAM) was applied,it restored the soil structure and greatly increased soil aggregate stabilization.This effectively prevented crust formation.However,this function of PAM was not continuously effective and the crust reformed with long-term rainfall.In co
基金supported by the National Science Foundation of China(No.41576076)the National Environmental Corrosion Platform(NECP)the National Key Basic Research Program(‘‘973 Program,’’No.2014CB643300)
文摘Experiments were designed to simulate the corrosion of a low-carbon steel exposed to a marine splash zone. The composition and morphology of the rust were investigated using Raman spectroscopy, X-ray photoelectron spectroscopy, energy-dispersive spectrometry and scanning electron microscopy. Corrosion resistance of the rust films was demonstrated by the electrochemical impedance spectroscopy. The wettability of the steel surface was calculated from the data conceruing the wetting degree and the conductivity. The results showed that, in the initial stage, the products of the outer rust layer were mainly made up of Fe（Ⅲ） oxyhydroxide, while the main component of the inner rust layer was magnetite. With an increase in the corrosion time, the inner rust layer continuously turned into the outer rust layer. In addition, both rust layers became dense, thus playing a protective role with respect to matrix. The existence of the rust layer significantly prolonged the residence time of the seawater on the sample surface, a result that tends to improve the cathodic protection effect for steel structures exposed to marine splash zones.
基金Natural Science Foundation of China,No.42077058,No.41601282,No.41867015Young Talent Fund of University Association for Science and Technology in Shaanxi,China,No.20210705+1 种基金Fundamental Research Funds for Central Universities,No.GK202309005Shaanxi Provincial Key Research and Development Program,No.2021ZDLSF05-02。
文摘Effective soil particle size composition can more realistically reflect the particle size sorting process of erosion.To reveal the individual contributions of rainfall intensity and slope to splash erosion,and to distinguish the enrichment ratio of each size and the critical size in splash,loessial soil collected on the Loess Plateau in May 2019 was tested under different rainfall intensities(60,84,108,132,156 mm h^(-1))and slopes(0°,5°,10°,15°,20°).The results demonstrated that 99%of splash mass was concentrated in 0–0.4 m.Rainfall intensity was the major factor for splash according to the raindrop generation mode by rainfall simulator nozzles.The contributions of rainfall intensity to splash erosion were 82.72%and 93.24%,respectively in upslope and downslope direction.The mass percentages of effective clay and effective silt were positively correlated with rainfall intensity,while the mass percentages of effective very fine sand and effective fine sand were negatively correlated with rainfall intensity.Opposite to effective very fine sand,the mass percentages of effective clay significantly decreased with increasing distance.Rainfall intensity had significant effects on enrichment ratios,positively for effective clay and effective silt and negatively for effective very fine sand and effective fine sand.The critical effective particle size in splash for loessial soil was 50μm.
基金Project Supported by the National Nature Science Foundation of China (Grant Nos: 50279033, 50539060)
文摘Atomized flow is an unnatural two-phase flow produced while water discharges in water release structures. This flow might threaten the normal operation of hydraulic and hydroelectric installations owing to the unnatural and high-density rain as well as the unnatural and dirty mist. The splash region, the region with the highest rain intensity, hence should receive much attention during the design and operation of the hydraulic and hydroelectric installations. In this paper rain intensity distribution in the splash region of the atomized flow is investigated experimentally, and the method of random simulation is used to predict the rain intensity distribution in the splash region.
文摘This study determined that the range of the marine splash zone (MSZ) of China’s Qingdao,Zhoushan. Xiamen. Zhanjiang harbour area was about 0-2.4 m above the mean high water level (MHWL) of the seawater that the MSZ corrosion peak (MSZCP) was usually 0.6- 1.2 m above the MHWL. and was caused by the large salt particle accumulation on the A3 carbon steel test sample surface and by the high frequency altemations of wet and dry environmental conditions around the samples.
