Rain Erosion Research Articles

A Study of Raindrop Impacts on a Wind Turbine Material: Velocity and Impact Angle Effects on Erosion MAPS at Various Exposure Times

Within renewable energy, challenging climates can impose great limitations on power generation. In wind energy, rain erosion on turbine blades can create major disruptions to air flow over the aerofoil, reducing the efficiency of the blade and immediately affecting the power output of the turbine. The defects in the materials that cause these inefficiencies are known and can be observed on turbines that have been in operation for extended periods. This work explores the transitions between different wear states for G10 Epoxy Glass under laboratory simulated wind turbine conditions in operation and measures the wear periodically to identify a progression of erosion. Mass loss data and micrographic analysis revealed samples at 45° and 60° displayed increasing erosion when examining erosion performance for angles between 15° and 90° over various exposure and velocities. Erosion maps were constructed, showing the variation of wastage and identifying the performance window of conditions where degradation is minimised.

Potensi Erosi Pada Penggunaan Lahan di Kecamatan Motoling Barat

Land use issues are the focus of research and land clearing on steep slopes and high rainfall in the research location is a trigger parameter for erosion. To determine the dangers of erosion, a research study was conducted on the potential for erosion in land use in the West Motoling District. This type of explorative descriptive research, with secondary data collection techniques. Processing and data analysis using the USLE (Universal Soil Loss Equation) method with a spatial approach through the Geographic Information System (GIS). Based on the results of the study, the level of erosion hazard in the West Motoling sub-district is dominated by very heavy erosion hazard classes (erosion rate > 480 ton/ha year) with an area of 6580.01 ha or 61.16% of the total area, spread over most of the new Raanan II village. Raanan Baru I, Kroit, Tondei I, Tondei II, and Toyopon. High rainfall with a rain erosivity index value of 11354.87 ton/ha year. The lowest erosion was 0.32 ton / ha / year, with latosol soil type reddish brown, flat slope class, jungle forest land cover and erosion levels were classified as very light criteria and the highest erosion was 12067.68 ton/ha year, with latosol soil types, very slopes. steep, residential land cover, and level of erosion are classified as very heavy criteria. The average erosion value (A) of 2012.52 ton/ha/year is classified as class V with a very heavy level of erosion. To reduce the rate of erosion, terracing can be used because with the presence of terracing it can reduce the surface flow velocity so that the erosion power of the soil and erosion is minimized.

Preparation and Optimum Proposal of Biological Dust Suppressant Using Straw Based on Orthogonal Test

In order to the prevent and control construction dust, and to avoid secondary pollution, on the basis of single factor experiment, the viscosity, surface tension, determination of water retention, and water absorption rate test were carried out in this paper, hydroxyethyl cellulose and hydroxypropyl methyl cellulose were selected as adhesive and water retention agent, Y1 and J1 were selected as surfactant and water absorption from straw extract of a variety of functional raw materials. Taking the viscosity of solution, pH value, water loss rate at high temperature, shell compressive strength and infiltration time as the assessment indexes, a four-factor and three-level orthogonal test was designed to optimize each component of the dust suppressant. A green, environmentally friendly and degradable straw dust suppressant was prepared, and the pilot test was carried out in the construction site of expressway. The orthogonal test results show that the influence degree of mass concentration of the four factors on the performance of straw utilization type dust depressant is as follows: hydroxyethyl cellulose has the greatest influence, followed by J1, and hydroxypropyl methyl cellulose and Y1 have the least influence. When hydroxyethyl cellulose, hydroxypropyl methyl cellulose, J1, Y1 mass concentration 0.35%, 0.03%, 0.05% and 0.03% respectively, the straw utilization type dust suppression agent viscosity value is 106.3mpa·s, and water-retention rate is 22.51%, pH value is 7.23, and has the compressive strength of 79.02 KPa and the infiltration time of 4.21 min, its density is 1.030 g/cm, Product viscosity is moderate, it spray easy, surface tension is small, meet the requirements of the current class of coal dust suppression agent products indicators. Highway field pilot test shows that, the surface have the shaw hardness of 70HA of shell in four hours after the construction site is sprayed biological dust suppressant in accordance with the dosage of 3 L/m2, the shell can effectively stop the rain and wind erosion, PM2.5 and PM10 dust suppression rate are 91.2%, 91.4% and 79.2% and 77.7% in the 1 d and 7 d respectively, have very good inhibition effect on construction dust.

Experimental study on performance of fiber concrete under simulated acid rain environment

This experiment studies the influence of different fiber content on the mechanical properties of concrete under simulated acid rain environment (pH=2.5) in the laboratory. Under the action of acid rain erosion, the total content of carbon fiber and basalt fiber are respectively 0.1%, 0.2%, and 0.3%, of which carbon fiber and basalt fiber each account for 50% of the total content. The experiment adopts the cycle immersion method to study the laboratory to simulate acid rain to accelerate the corrosion of concrete. After simulating acid rain corrosion for 25 days, it is naturally dried for 5 days. The compressive strength and splitting tensile strength are measured. The comparison shows that when the total fiber content is 0.2%, the concrete the tensile-compression ratio of the test block is the largest, and its splitting tensile strength increases by 15.09% as the maximum.

Correction to: Rain Erosion Maps for Wind Turbines Based on Geographical Locations: A Case Study in Ireland and Britain

Correction to: Rain Erosion Maps for Wind Turbines Based on Geographical Locations: A Case Study in Ireland and Britain

An Experimental Study on the Dynamic Mechanical Properties of Epoxy Polymer Concrete under Ultraviolet Aging.

Epoxy polymer concrete (EPC) is widely applied in engineering for its excellent mechanical properties. The impact loads and severe climatic conditions such as ultraviolet radiation, temperature change and rain erosion are in general for its engineering practice, potentially degrading the performance of EPC. In this paper, a procedure of accelerated aging for EPC, imitating the aging effect of ultraviolet radiation and hygrothermal conditions based on the meteorological statistics of Guangzhou city, was designed. After various periods of accelerated aging, the dynamic behaviors of EPC were studied by using a Split Hopkinson Pressure Bar (SHPB). The verification of the experimental data was performed. The two-stage dynamic compression stress-strain curves were obtained: (a) linear growth stage following by strain hardening stage at impact velocity 12.2 m/s and 18.8 m/s, (b) linear growth stage and then a horizontal stage when impact velocity is 25.0 m/s, (c) linear growth stage following by strain softening stage at impact velocity 29.2 m/s. The experimental results show that the specimens after longer accelerated aging tend to be more easily broken, especially at impact velocity 12.2 m/s and 18.8 m/s, while the strain rate is the main factor affecting the compression strength and stiffness. Ultimately the influence of strain rate and equivalent aging time on dynamic increase factor was revealed by a fitting surface.

Mechanism and erosion resistance of internally cured concrete including super absorbent polymers against coupled effects of acid rain and fatigue load

This study explored a novel method for inhibiting the effects of acid rain erosion and fatigue loading in concrete by incorporating super absorbent polymers (SAP). Three different dosages and four particle sizes of SAP were considered to evaluate the erosion resistance to a simulated acid rain solution (pH = 3.0) for eight test cycles. The mass loss, compressive strength, flexural strength, and erosion depth as well as the results of X-ray diffraction (XRD) and the mercury intrusion porosimetry (MIP) testing were employed to explore the erosion behavior and mechanism of the internally cured concrete with SAPs. The results show that the coupled effects of acid rain and fatigue loading has a remarkable influence on the performance degradation of concrete. The erosion of concrete by acid rain was delayed and weakened with the addition of SAP, particularly when 0.10% SAP was added with a particle size of 100–120 mesh. Moreover, the SAP promoted hydration, which lessened the deterioration caused by pore deformation and improved the internal pore structure.

Rain Erosion Load and Its Effect on Leading-Edge Lifetime and Potential of Erosion-Safe Mode at Wind Turbines in the North Sea and Baltic Sea

Leading-edge erosion at wind turbine blades cause a loss in profit for wind farm owners, in particular offshore. The characterization of the rain erosion environmental load at wind turbine blades is based on the long-term rain rate and wind speed observations at 10-minute resolutions at coastal stations around the North Sea, Baltic Sea, and inland. It is assumed that an IEA Wind 15 MW turbine is installed at each station. The leading-edge lifetime is found to increase from the South to the North along the German and Danish North Sea coastline from 1.4 to 2.8 years. In the Danish and German Baltic Sea, the lifetime in the West is shorter (~2 years) than further East (~3 to 4 years). It is recommended to use a time series of 10 years or longer because shorter time series most likely will cause an overestimation of the lifetime. The loss in profit due to leading-edge erosion can potentially be reduced by ~70% using the erosion-safe mode, i.e., reduce the tip speed during heavy rain events, to reduce blade erosion, aerodynamic loss, repair costs, and downtime during repair. The aerodynamic loss for the 18 stations is on average 0.46% of the annual energy production.

Concentrations Assessment Of Radon Gas and Some Radioactive Nuclei For Some Region In Basra Governorate By CR-39 Detector

In this work, eighteen samples were studied distributed over different sites in Basra Governorate from southern Iraq. The CR- 39 nuclear trace detector technique was used to reach the results, which showed us, the radium concentrations ranged between (18.52 - 2.169) Becquerel / kg, the environmental factors such as rain, dust and weather erosion have led to a decrease in radium concentrations in these areas which fell within the permissible range of 33 Becquerel / kg. The concentrations of uranium in the samples under study ranged from 0.2622 ppm to 2.239 ppm, is higher than the natural limit of the background radiation (0.2 - 1.2) ppm, which indicates that radioactive pollution has entered the Iraqi environment. As well as, we find that the concentration of Radon The samples have risen by twenty times the normal limit in some samples, which indicates the danger of dealing with the polluted southern environment of Iraq.

EROSI DAN SEDIMENTASI PADA SUB DAS AIR BETUNG KOTA PAGAR ALAM BERBASIS SISTEM INFORMASI GEOGRAFIS (SIG)

Watershed Area is a land area that receives rain water to then flow it back through one main river to downstream. Watershed section upstream is often the focus of watershed management planning because in addition to its, as acatchment, there are alsonbiophsical links to downstream areas. This study aims to determine the level of erosion and sedimentation in Air Betung sub-watershed. Erosion and sedimentation analysis used the formula USLE (Universal Soil Loss Equation) which was influenced by faktors such as, rain erosion index (R), soil erodibility index (K), slope length and slop (LS), management factor values safe and assement of land coversation factors (CP). Based on the result of the analysis with using the USLE method and approached with ILWIS 3.3 showed that value erosion was 54,565.73 tons/ha/year. From the results of measurements in the large sediment field hovering that occured in Betung sub-watershed was 1.26 grams in 2L water with debit 5.25m3/sec

Change in erosion potential of crops due to climate change

Erosion by water on arable land can be influenced by the farmer mainly by crop selection, cultivation and field management. This requires updated knowledge on the erosion potential of crops, the so-called C factor of the (Revised) Universal Soil Loss Equation. In order to assess how climate change has already altered the C factors, we analysed the effects of a modified crop development and rain erosivity. To this end, we combined more than 4.2 million phenological observations in Germany with the seasonal distribution of rain erosivity derived from contiguous rain radar measurements comprising about 7.7 million events. We then compared the recent C factors to those derived in the 1980s. Due to temperature increase, crops developed earlier and / or faster, which was particularly true for maize due to its C4 mode of photosynthesis; and rains were more erosive during the dormant season. Both had a strong impact on the C factors. In particular, the C factor of maize decreased while that of winter cereals tended to increase because these crops pass the winter period in a stage susceptible to erosion. In consequence, the differences among crops in their erosion potential decreased. Our findings strongly suggest that the winter period has to receive larger attention in soil conservation. Thus, the use of winter cover crops may become even more effective to control erosion.

Degradasi Lahan dan Implikasinya terhadap Rencana Pola Ruang di Daerah Dataran Tinggi

Land degradation is a phenomena of the decreasing in land use function, potential use and irreplaceable organism. Many causes result in land degradation such as soil erosion, rain erosion which are all accelerated by human activities example agricultural activity. Increased agricultural activity is caused by an increase in population and also increasing food needs. Land exploitation for agricultural activities result in land degradation such as planting on conservation areas that cause erosion. Kledung Sub-district is one of the regions that practices massive agricultural land use and plants in a conservation land. Practices in Kledung Sub-district have caused floods and soil erosion in Kledung Sub-district in the last few years. The purpose of this study was to determine the level of land degradation that occurred in Kledung Sub-district and its implications for the land use planning to increase awareness of various parties about the dangers of land degradation. This research was conducted primarily by observation and secondary b examining documents about the indicators causing land degradation and conducting descriptive and quantitative analyzes. The quantitative analyze is using RUSLE (Revised Universal Soil Loss Equation). The analysis shows that the majority of erosion according to the Ministry of Forestry is moderate (>60-80 tons/ha/yr) covering1.231,01 Ha and according to Hammer which is very high (>100 tons/ha/yr) covering 469,62 Ha or 12,7% of the total area of Kledung Sub-district with a high level of erosion hazard it is necessary to evaluate the land use planning of Kledung Sub-district so that it can adjust the land use planning and the erosion hazard level in Kledung Sub-district.

Estimativa da vulnerabilidade dos solos à erosão hídrica na bacia hidrográfica do Rio das Mortes (MG)

A erosão hídrica é uma das maiores causas de degradação dos solos no mundo, sendo responsável por perdas de solo superiores às taxas naturais de reposição. Objetivou-se estimar a distribuição espacial do potencial anual médio de perda de solo na bacia hidrográfica do Rio das Mortes (MG), com a finalidade de identificar as áreas mais susceptíveis à erosão hídrica e fornecer subsídio para a gestão dos recursos naturais na região. Para isso, foi aplicado o modelo RUSLE (Revised Universal Soil Loss Equation) implementado em ambiente SIG. O fator erosividade da chuva foi obtido com base em um modelo geográfico multivariado desenvolvido para o Brasil; o fator cobertura e manejo do solo foi derivado do mapa de uso do solo do Brasil; o fator erodibilidade do solo foi obtido pelo mapa de solos de Minas Gerais; e o fator topográfico foi obtido pelo modelo digital de elevação. Os mapas dos fatores foram combinados por meio de álgebra de mapas, originando o mapa de vulnerabilidade dos solos à erosão hídrica. Observou-se que 45,20% dos solos da bacia hidrográfica estudada apresentaram “Ligeira” vulnerabilidade à erosão hídrica. No entanto, 50,28% da área da bacia apresentaram perda de solo superior a 10 t ha-1 ano-1, o que indica a existência de áreas altamente susceptíveis à erosão hídrica e evidencia a necessidade de implementação de melhorias no manejo e práticas conservacionistas do solo.

Rain erosion of wind turbine blades and the effect of air bubbles in the coatings

AbstractLeading edge erosion on a wind turbine blade from Vindeby offshore wind farm is characterized by X‐ray tomography, and air bubbles within the top coat are observed. Similar coating systems with and almost without air bubbles within the top coat are tested on a R&D Test Systems style whirling arm rain erosion tester (RET) and found to have different V–N curves. In general, the slope of the two curves was comparable. However, the absolute performance value with RET differs significantly with up to 2.6 times performance advantage to the coating with less bubbles. A micromechanical model of the coating system that takes the air bubbles into account has been developed, and air bubbles are found to have critical effect on the crack initialization in the coating.

A computational framework for coating fatigue analysis of wind turbine blades due to rain erosion

The rain-induced fatigue damage in the wind turbine blade coating has attracted increasing attention owing to significant repair and maintenance costs. The present paper develops an improved computational framework for analyzing the wind turbine blade coating fatigue induced by rain erosion. The paper first presents an extended stochastic rain field simulation model that considers different raindrop shapes (spherical, flat, and spindle), raindrop sizes, impact angles, and impact speeds. The influence of these raindrop characteristics on the impact stress of the blade coating is investigated by a smoothed particle hydrodynamics approach. To address the expensive computational time, a stress interpolation method is proposed to calculate the impact stress of all raindrops in a random rain event. Furthermore, coating fatigue analysis is performed by including the fatigue crack initiation in the incubation period and the fatigue crack propagation in the mass-loss-rate increasing period due to raindrop impact. Finally, the proposed computational framework is verified by comparing the estimated fatigue life with those obtained in literature. The results from the study show that by incorporating the statistics of rainfall data, the proposed framework could be used to calculate the expected fatigue life of the blade coating due to rain erosion.

Analysis on the applicability of modified polyvinyl alcohol (MPA) for temporary controlling the dust from soil in construction site

ABSTRACT Dust from construction field is one of sources for the atmosphere particulate pollution. In this study, a solidifying material, modified polyvinyl alcohol (MPA), is used to control the dust from soil. The controlling efficiency of the MPA is evaluated based on its anti-wind and anti-rain erosion performance under different conditions such as soil types, spraying amount of MPA, slope morphologies (gradients and unevenness), and treated time. Results indicate that the MPA can bind well with the soil particles and it is able to strengthen the integrity of the surface. Soil treated with MPA exhibits good anti-wind effects, and PM10 and PM2.5 in environment do not increase even under a nine-grade wind erosion. Soil treated with MPA can maintain the surface integrity under a rainstorm, and there are no erosion traces and mud after rain erosion. The application of MPA has no limitation in terms of soil type, soil slope, and surface morphology, and thus, it has a wide applied prospect in engineering. Implications: In order to solve the air pollution problems existing on construction sites in densely populated areas, MPA optimizes a kind of environmental agent to treat, which does not affect the later use of soil. The applicability effect was verified from the perspective of anti-wind and anti-rain erosion doubly. Research results not only can provide data support for the construction management, but also help to promote the civilization and ecological benefit of construction.

Methodology for the energetic characterisation of rain erosion on wind turbine blades using meteorological data: A case study for The Netherlands

AbstractRain erosion on the leading edge of wind turbine blades is an intricate engineering challenge for the wind industry. Based on an energetic approach, this work proposes a methodology to characterise the erosion capacity of the raindrop impacts onto the leading edge blades. This methodology can be used with meteorological data from public institutions or from direct measurements at the wind turbine locations. The erosion characterisation is analysed using accumulative and per impact erosive variables, that is, total kinetic energy and kinetic energy per impact. To consider the frequency of impacts, two erosive variables are proposed, namely, total kinetic power and kinetic power per impact. These variables are calculated using the data from the Royal Netherlands Meteorological Institute (Koninklijk Nederlands Meteorologisch Instituut, KNMI) of the last 25 years jointly with the operation specifications of an actual wind turbine model (Suzlon S111). The main contribution to the erosive variables was found to be the wind speed because it controls the rotational velocity of the wind turbine. Also, the intensity of the rainfall and the frequency of meteorological data logging, that is, the temporal resolution of data, play a significant role.

Machine learnt prediction method for rain erosion damage on wind turbine blades

AbstractThis paper proposes a paradigm shift in the numerical simulation approach to predict rain erosion damage on wind turbine blades, given the blade geometry, its coating material, and the atmospheric conditions (wind and rain) expected at the installation site. Contrary to what has been done so far, numerical simulations (flow field and particle tracking) are used not to study a specific (wind and rain) operating condition but to build a large database of possible operating conditions of the blade section. A machine learning algorithm, trained on this database, defines a prediction module that gives the feature of the impact pattern over the 2‐D section, given the wind and rain flow. The advantage of this approach is that the prediction becomes much faster than using the standard simulations; thus, the study of a large set of variable operating conditions becomes possible. The module, coupled with an erosion model, is used to compute the erosion damage of the blade working on specific installation site. In this way, the variations of the flow conditions due to dynamic effects such as variable wind, wind turbulence, and turbine control can be also considered in the erosion computation. Here, we describe the method, the database creation, and the development of the prediction tool. Then, the method is applied to predict the erosion damage on a blade section of a reference wind turbine, after one year of operation in a rainy onshore site. Results are in good agreement with on field observations, showing the potential of the approach.

Crack Identification Method of Steel Fiber Reinforced Concrete Based on Deep Learning: A Comparative Study and Shared Crack Database

As a common disease of concrete structure in engineering, cracks mainly lead to durability problems such as steel corrosion, rain erosion, and protection layer peeling, and then the building gets destroyed. In order to detect the cracks of concrete structure in time, the bending test of steel fiber reinforced concrete is carried out, and the pictures of concrete cracks are obtained. Furthermore, the crack database is expanded by the migration learning method and the crack database is shared on the Baidu online disk. Finally, a concrete crack identification model based on YOLOv4 and Mask R‐CNN is established. In addition, the improved Mask R‐CNN method is proposed in order to improve the prediction accuracy based on the Mask R‐CNN. The results show that the average prediction accuracy of concrete crack identification is 82.60% based on the YOLO v4 method. The average prediction accuracy of concrete crack identification is 90.44% based on the Mask R‐CNN method. The average prediction accuracy of concrete crack identification is 96.09% based on the improved Mask R‐CNN method.

Constitutive model of confined concrete with stirrups by acid rain erosion

In order to study the influence of stirrup corrosion level on the peak stress, peak strain, ultimate strain and shape of stress-strain curve of the confined concrete, 15 reinforced concrete prism specimens were subjected to acid rain erosion by artificial climate simulation technique followed by axial pressure tests. Based on Mander’s model and the existing research results, the calculation formulas of the peak stress f’ cco, peak strain £cco, ultimate strain ε cco, ultimate strain ε cu0 and shape factor r of the uncorroded specimens are determined. The factor calculation formulas for peak stress, peak strain, ultimate strain and shape factor of corroded specimens is developed by regression analysis of test data, respectively, and then the constitutive model of confined concrete by acid rain erosion is established. By comparing the simulation results with the experimental data, it can be found that all the peak stress, peak strain, ultimate strain and stress-strain curves shape of the specimens obtained by the proposed method are in good agreement with the experimental data. Thus the constitutive mode for confined concrete established in this paper can accurately reflect the mechanical performance of RC prism specimen by acid rain erosion, indicating its adaptiveness for estimating the residual bearing capacity and the seismic performance of RC structure under the acid rain environment.