Erosion Damage Research Articles

NMR Experimental Study on Dynamic Process of Pore Structure and Damage Mechanism of Sandstones with Different Grain Sizes under Acid Erosion

In many engineering projects, it is critical to consider the acid erosion of rock. This study investigates dynamic changes in pore structure and damage mechanisms in sandstones subjected to acid erosion. Specimens with three grain sizes were immersed in acid solution and tested by the nuclear magnetic resonance technique. Changes in solution pH, specimen mass and porosity, T2 spectrum distribution, and area were analyzed. Damage mechanisms are discussed, and relationships between porosity and acid erosion damage variables are established. The results show that acid erosion has significant effects on pore structure and erosion damage in sandstone. With increasing soaking time, new micropores formed in sandstone, while existing micropores and mesopores gradually expanded into macropores, causing the T2 spectrum distributions to change greatly. The porosity, acid erosion damage, and T2 spectral areas of sandstones with different grain sizes all increased gradually. Under acid erosion, sandstones became gradually weakened, but the effects varied greatly according to grain size. Pore structure changes and acid erosion damage were greatest in coarse-grained sandstone, followed by medium- and fine-grained sandstone.

The impact of inlet flash evaporation conditions on erosion damage characteristics of coal gasification black water angle valve and prevention strategies

In view of the three-stage flash evaporation system of the coal gasification plant, a combination of theoretical analysis and numerical simulation was used to establish the erosion damage evaluation model in the black water angle valve. The influence of the inlet flash evaporation ratio on the inlet velocity, the outlet flash evaporation ratio and the outlet velocity of the low-pressure black water angle valve are systematically studied, the mechanism of erosion damage to the carbon steel valve body by the solid medium in black water was analyzed according to the micro-cutting theory. The results show that the inlet velocity w 1, the outlet flash evaporation ratio x 2, the outlet velocity w 2 of angle valve have linear correlation with the inlet flash evaporation ratio x 1.The upstream volume erosion ratio of the angle valve at the inlet flash ratio x 1 = 3 wt.% is 114 times as much as that at zero inlet flash ratio. Meanwhile, the downstream volume erosion ratio of the angle valve at x 1 = 3 wt.% is only 2.7 times as much as that at zero inlet flash ratio. The prevention strategies to reduce the erosion damage to black water angle valve are proposed by inhibiting the inlet flash evaporation ratio and reducing the inlet flow rate etc. This study is expected to provide guidance for the erosion resistance design and operation of the black water angle valve.

Modern Approaches to Environmental and Economic Estimation of Damage From Soil Erosion

Actuality. Despite a nearly century-old history of erosion damage assessments, this issue has not yet been finally resolved. If the economic component of losses can be relatively easily calculated, then environmental and socio-environmental damage are almost impossible to calculate. Purpose. To show the possibilities and limitations of using individual indicators for assessment of damage and the environmental and economic justification of anti-erosion measures based on analysis of the environmental, economic and social consequences of soil erosion, and world experience in assessing damage from erosion. Results. Losses from erosion today are most often estimated by the mass of washed soil (t / ha), the cost of restoring lost nutrients and organic matter, as well as the cost of agricultural products lost due to reduced yields on eroded soils and stop cultivation of hard eroded soils. Soil losses are usually estimated by mathematical modeling. Different approaches to the assessment of losses give a ten-fold difference in the estimates, which reduces the credibility of them when making decisions. Land users are not interested in investing in anti-erosion measures more than the cost of the crop, which they can additionally receive. In Ukraine, this leads to a de facto neglect of the problem of erosion, which, developing on the principle of positive feedback, leads to the deepening of socio-economic problems and the deterioration of the country's food security Conclusions. To justify anti-erosion measures at the level of land users, the only reliable source for quantifying the potential damage from erosion is the shortage of agricultural products and the loss of soil organic matter and fertilizers. The real damage from erosion lies in the plane of global environmental processes and food security, therefore, the problem of erosion should be addressed at the national level.

长脉冲激光辐照单晶硅的热损伤

In view of the thermal damage law and mechanism of monocrystalline silicon for millisecond pulsed laser, the temperature of monocrystalline silicon irradiated by millisecond pulsed laser is measured by high precision point temperature meter and spectral inversion system. Then the temperature evolution process is analyzed. Also, the temperature state during the whole process of thermal damage of monocrystalline silicon irradiated by millisecond pulsed laser and the corresponding damage structure are studied. The results of this study show that the peak temperature of laser-induced monocrystalline silicon increases with the increase of energy density when the pulse width is fixed, When the pulse width is between 1.5 ms-3.0 ms, The temperature decreases with the increase of pulse width. Temperature rise curve shows inflection point when it is close to the melting point (1687 K), the reflection coefficient is from 0.33 to 0.72. During the gasification and solidification stages, it also shows the gasification and the solidification plateau periods. Thermal cleavage damage of monocrystalline silicon precedes thermal erosion damage. Stress damage dominates under low energy density laser irradiation, while thermal damage dominates under high energy density laser irradiation. The damage depth is proportional to the energy density and increases rapidly with the increase of the number of pulses.

Effect of erosion on corrosion of API X120 steel in relation to erodent particle size

The nature of the solid erodent particles present in corrosive petroleum fluid can cause transporting pipeline to experience severe erosion and corrosion damages. The effect of erosion on corrosion behavior of API X120 steel was investigated using aluminum oxide and silicon carbide particles with different sizes as erodent and 3.5 wt.% NaCl aqueous solution saturated with carbon dioxide as a corrosive medium. The effect of the erodent particle size on the corrosion behavior of the steel material at different particle speeds and impact angles was investigated using weight loss, potentiodynamic polarization and surface analysis techniques. The erosion results confirmed that the material damage increased with increasing particle speed. It was observed that in carbon dioxide-saturated saline solution, deposition of protective iron carbonate film occurred on the steel surface. It was found that the corrosion film can provide better protection at lower particle speed than at higher speed. The ratio of total erosion–corrosion (S)/effect of erosion on corrosion (T) analysis confirmed that at higher S/T ratio, the particle speed and material removal rate are low and vice versa at lower S/T ratio. Lower S/T values for the combined erosion and corrosion tests performed with erodent silicon carbide particle compared to erodent aluminum oxide particle showed that erosion enhancement of corrosion is more evident in the test performed using aluminum oxide particle than using silicon carbide particle. The result also suggests that when subjected to larger size erodent particle, the damage to pipeline due to effect of erosion on corrosion process can be more significant compared to smaller size erodent particle.

The new model of erosion destroying

A new physical (experimental) model of cavitation destruction of the studied materials is proposed. In the mo-dern model of the cavitation effect, the destruction of materials is associated with the impacts of cumulative jets, which are formed during the asymmetric slamming of cavitation bubbles near the solid surface and the shock waves that occur during their compression. In the new model, erosion damage is explained by the formation of cavitation tubes (с-tubes) with a spiral high-frequency structure in the materials under study that were previously unknown in the literature. The destruction of materials is associated with the focusing of acoustic energy along the axis of the spiral structures. When focusing energy, there is a significant increase in pressure and temperature along the axis of the spiral structures, which leads to the destruction of the materials under study.

Prediction of Cavitation Erosion Intensity Using Large-Scale Diesel Nozzles

<div class="section abstract"><div class="htmlview paragraph">In the field of heavy-duty diesel engines, which require lifetime durability and high fuel efficiency, there is a growing demand for increased injection pressure and increased flow rate inside injection holes. This trend makes it important to prevent cavitation erosion of injector nozzles. This paper aims to clarify the relation between cavitation behavior and erosion damage experimentally by visualizing the flow inside diesel nozzles and to establish a new method for predicting cavitation erosion. To visualize internal flow, authors used the large-scale transparent nozzle whose Reynolds number and Cavitation number were matched with those of the actual real-size nozzle. Direct observation showed that the form of the cavitation changed from string-type cavitation to film-type cavitation with increasing needle lift. In addition, comparison between the locations where cavitation bubbles collapse and the locations where erosion occurs suggested that collapse of the film-type cavitation at high needle lift contributed significantly to the erosion damage. Furthermore, it is found that the location and intensity of erosion can be predicted by calculating the local quantity of film-type cavitation collapse.</div></div>

Application of Storm Erosion Index (SEI) to parameterize spatial storm intensity and impacts from Hurricane Michael

Hurricane Michael made landfall as a Category 5 Hurricane on 10 October 2018 between Mexico Beach, Florida and Tyndall Air Force Base in Panama City Beach, Florida causing damages totaling $25 billion (Beven et al. 2019). While damages were caused by both wind and surge, this paper is solely concerned with the surge induced damages which were observed predominantly within 50 km (27 nmi) of the hurricane’s path. Generally, regions to the east of Hurricane Michael’s landfall sustained the most severe damages and appear consistent with the spatial gradient in peak water levels. This gradient was marked; with surge induced damage concentrated in the immediate vicinity of Mexico Beach and attenuating significantly over distances as little as 37 km (20 nmi) to the west in Panama City Beach and east in Port Saint Joe (Kennedy, in review). The gradient in erosion was also pronounced, with Panama City Beach experiencing an average erosion rate of 0.4 m3/m (3.9 cy/ft) while Mexico Beach and Cape San Blas experienced rates approximately three (1.1 m3/m or 11.5 cy/ft) and five (1.7 m3/m or 18.5 cy/ft) times that. For inherent reasons, the pronounced gradient in surge damages and erosion values are of primary interest to coastal researchers and managers. Storm Erosion Index (SEI), developed by Miller and Livermont (2008) combines the three primary drivers of coastal erosion (wave height, total water level, and storm duration) into a physically meaningful form to evaluate storms based on their erosion potential. Here, SEI is applied to explore these spatial variations at seven distinct regions within the Florida Panhandle and are compared to the observed impacts for both erosion and structural damages. These regions include: (west to east) Panama City Beach, Tyndall Air Force Base (AFB), Mexico Beach, Cape San Blas, Port St. Joe, St. Vincent Island, and St. George Island. Empirically, the cumulative SEI relates well with the observed beach erosion; while the Peak Erosion Intensity (PEI) was found to better capture the trends in structural damages. By capturing the spatial variation of the storm intensity, SEI and PEI are therefore proposed as a viable engineering demand parameter with potential applications in community scale fragility curves.

Key Problems Affecting the Anti-Erosion Coating Performance of Aero-Engine Compressor: A Review

Sand erosion has always been a key threat to the performance and service life of aero-engines. The compressor, the key component installed at the front of the aero-engine, suffers the most from sand erosion, especially compressors serving in deserts. Ceramic hard coating is a traditional way to improve the hardness and wear resistance of cutting and grinding tools. It may also be used to improve the erosion resistance of aero- engine compressor. However, the mechanism of erosion damage is complicated, which may include wear, secondary erosion, anisotropic erosion, impact, and fatigue. Recent research discovered the major problems with ceramic hard coating on aero-engine compressors. In this paper, these following problems are discussed: the design of coating material and structure, the preparation method and technology, the effects of droplets and clusters of coating surface, microstructure and characteristics of interface. The review of the major problems and possible solutions discussed in this paper may contribute to the future research on erosion coating theoretically and practically.

A New Model of Erosion Destruction

A new physical (experimental) model of cavitation destruction of the materials studied is proposed. In the modern model of the cavitation effect, the destruction of materials is associated with the impacts of cumulative jets, which are formed during the asymmetric slamming of cavitation bubbles near the solid surface, and the shock waves that occur during their compression. In the new model, erosion damage is explained by the formation of cavitation tubes (с-tubes) with a spiral high-frequency structure in the materials under consideration, and these tubes were previously unknown in the literature. The destruction of materials is associated with the focusing of acoustic energy along the axis of the spiral structures. When the energy is focused, there is a significant increase in the pressure and temperature along the axis of the spiral structures, which leads to the destruction of the materials under study.

Experimental and numerical analysis of solid particle erosion on grinding tool in polymer-flooding wastewater treatment

The particles in polymer-flooding wastewater can cause the grinding tool erosion failure during the grinding process, resulting in the grinding tool not meeting the treating requirement. In this paper experimental and numerical analysis methods are used to explore erosion failure phenomenon, erosion mechanisms, for reducing the erosion damages of the grinding tool during polymer-flooding wastewater treatment processes. Based on the three-dimensional numerical simulation, the maximum erosion surface is found and the erosion rates of different surfaces of the grinding tool are calculated. The validity of the simulation model is verified by on-site experimental value. Combined with erosion morphology observation of samples cut from the grinding tool by SEM and the flow characteristics analysis by CFD, two erosion mechanisms are proposed basing on different flow fields. Furthermore, the effect between operating parameters (rotating speed, flow rate) and the erosion rate of the grinding tool is investigated and the mathematical model is built. Based on this mathematical model, operating parameters are optimized to improve the corrosion resistance and extend service life of the grinding tool during the polymer-flooding wastewater treatment.

Experimental Study on CO2 Corrosion of Super 13Cr Integrated Tubing with Erosion Damage

Integrated tubing can be used in the process of both fracturing and production for the oil and gas industry. During the process of fracturing, the inner surface of the tubing is subjected to the erosion from the slurry with sand and fracturing fluid, and then in the process of production, it is also corroded by the high-CO2-containing multiphase medium. To evaluate the CO2 corrosion resistance of Super 13Cr tubing after erosion in fracturing, the erosion test of Super 13Cr tubing under different impact angles was carried out by the jetting facility. For the samples with different erosion damage, the high-temperature and high-pressure CO2 corrosion experiments were carried out. The CO2 corrosion morphology with different erosion damage was also analyzed by SEM. The results show that different erosion damage at different impact angles can affect the corrosion rate in the later CO2 corrosion test. At an impact angle of 30°, the erosion damage is mainly caused by the cutting and plowing mechanisms by the eroded particles. The craters and folded extruded lips on the surface of the Super 13Cr tubing are formed and the passive film of super 13Cr is removed on the bottom of the craters, resulting in a corrosion rate that was approximately 1.4 times greater than that of the non-eroded surface. However, at the impact angle of 90°, the erosion mechanism is the plastic deformation and many platelets are formed. Less contact area between the fresh surface without passive film and the corrosive medium results in a lower corrosion rate than the material with 30° impact erosion damage.

Erosion behavior and influence of solid particles in hydraulic spool valve without notches

Hydraulic spool valve without notches is used as a kind of important amplification component in hydraulic servo valve. Its static and dynamic properties have a significant impact on the performance of servo valve and hydraulic system. Under solid particles erosion in oil, the metering edges of spool valve were usually eroded and worn. This process was irreversible and induced serious control performance degradation of orifice and valve. In this paper, the erosive behavior and influence of solid particles in hydraulic spool valve without notches were investigated. By the surface microtopography measurement of the spool, erosion corners failure were present. The CFD simulation of solid-liquid two-phase flow was carried out by discrete phase model (DPM) to analyze the erosion failure. The migration route of the severe erosion region of hydraulic spool valve without notches was obtained and the mechanism of local erosion was revealed. An interesting phenomenon of erosion inflection point and face-back flow was found. The exact calculation method of the orifice area under erosion was discussed and put forward. This paper provides a reference for further study on the erosion damage and erosion resistance of hydraulic spool valve without notches.

Failure analysis of first stage nozzle in a heavy-duty gas turbine

First stage nozzles are considered as one of the most critical components in the heavy-duty gas turbines because of their operational in-service condition in the hot gas path. In the present research, the failure analysis of a first stage nozzle in a159 MWgas turbine is investigated in order to specify the modes and mechanisms of the failure and their root causes. Various examinations including macroscopic and visual inspection of the nozzle outer surface, the micro examination of the fracture surface, chemical analysis and metallographic analysis were carried out to complete the investigation. The micro and macro examinations revealed cracks, erosion and oxidation damages in the nozzle investigated. These failures were caused by overheating and improper filtration of the turbine inputs which activated the thermal fatigue failure mode. Finally, in order to estimate the nozzle life and predict the failure occurrence, a modified model is developed using Robinsons rule and its extension for total damages of first stage nozzle based on statistical data gathered in a periodic inspection conducted during operation.

Corrosion and Cavitation Erosion Behaviours of Cast Nickel Aluminium Bronze in 3.5% NaCl Solution with Different Sulphide Concentrations

The effect of sulphide (Na2S) concentration (SC) on the corrosion and cavitation erosion behaviours of a cast nickel aluminium bronze (NAB) in 3.5% NaCl solution is investigated in this study. The results show that when the SC exceeds 50 ppm, the hydrogen evolution reaction dominates the cathodic process, and a limiting current region appears in the anodic branch of the polarisation curve due to the formation of a copper sulphide film, which is a diffusion-controlled process. After long-term immersion, the increased mass loss rate of NAB with the sulphide additions of 20 and 50 ppm is attributed to the less protective films, which contains a mixture of copper oxides and sulphides. Moreover, NAB undergoes severe localised corrosion (selective phase corrosion, SPC) at the β′ phases and eutectoid microstructure α + κIII. By comparison, NAB undergoes general corrosion and a copper sulphide film is formed in 100 and 200 ppm sulphide solutions. Cavitation erosion greatly increases the corrosion rate of NAB in all solutions and causes a negative potential shift in 3.5% NaCl solution due to the film destruction. However, a positive potential shift occurs in the solutions with SC higher than 50 ppm due to the accelerated mass transfer of the cathodic process. The cavitation erosion mass loss rate of NAB increases with the increase of SC. The occurrence of severe SPC decreases the phase boundary cohesion and causes brittle fracture under the cavitation impact. The corrosion–enhanced erosion is the most predominant factor for the cavitation erosion damage when the SC exceeds 50 ppm.

An experimental investigation of fracturing fluids on physico-mechanical damage properties of carbonates in block Shunbei

ABSTRACT For the purpose of revealing the effect of fracturing fluids on rock breaking, wellbore stability, and fracturing reformation. A multi-scale evaluation method is initially established in the paper by analyzing and investigating based on laboratory experiment of different fracturing fluids on Physico-mechanical Damage Properties of Carbonates. This paper has taken carbonate reservoir of block Shunbei in Xinjiang as the research object, the influence of different fracturing fluids on physico-mechanical properties and damage mechanism has been deeply studied by microanalysis, laboratory physical and mechanical tests and theoretical analysis. The results show that gelled acid has a remarkable time-effect on the deterioration of physical and mechanical properties of the carbonate samples, and the optimal degradation time is 30 min. The impact degree of three fracturing fluids is discrepant, and the damage effect of gelled acid is more significant than that of cross-linked acid and slickwater, for physical properties and micro-composition have the largest attenuation, and the spacing between mineral crystals increase, with the arrangement becoming looser. For mechanical damage characteristics, the deterioration and attenuation of rock mechanical properties including rock compressive, tensile and shear strength are significant, and the failure mode changes from a single fracture to multiple fractures. The mechanism on the physico-mechanical damage characteristics of carbonate rock is mainly caused by the physical deterioration, chemical erosion, and mechanical damage. In summary, based on the degradation effect and influence degree of the three fracturing fluids on the carbonates, their effects are as: gelled acid > cross-linked acid > slickwater, so gelled acid is more suitable as a fracturing fluid for a carbonate reservoir to enhance the complexity of crack propagation and achieve maximum volume of stimulation.

Numerical study on the effect of blade surface deterioration by erosion on the performance of a large wind turbine

As the demand for the development of onshore wind farms in areas with low wind speeds and large offshore wind farms increases, the size of the wind turbine and its rotor has also increased rapidly. An increase in the rotor diameter implies an increase in the relative wind velocity (with respect to each cross section in the radial direction of the blade) near the tip region of the blade. This in return accelerates the surface damage caused by the erosion of the leading edge, thereby increasing the frequency of maintenance and lowering competitiveness in the cost of energy. In this study, computational fluid dynamics (CFD) analysis was performed to analyze the correlation between the leading-edge erosion damage and output performance of the blade. CFD simulations were performed using a tip airfoil (NACA 64_618) and a full-scale wind turbine (NREL 5 MW) based on the state of erosion of discarded blades considering approximately 12 years of maintenance-free operation. The irregular erosion at the airfoil leading edge results in premature stall phenomena and reduces the aerodynamic efficiency. Thus, the accurate analysis of the flow separation point and flow change is necessary. Therefore, three-dimensional transient CFD analysis was performed to consider the complex flow generated on the blade surface. The erosion at the leading edge reduced the airfoil lift by up to 23% and drag by 100%, reducing the aerodynamic efficiency, which in effect reduced annual energy production by up to 4%.

Simulation of Microcontact Interactions during Gas-Abrasive Wearing of Steels with Allowance for Strain Hardening

In this paper, we present a model of the effect of the contact interaction velocity and the mechanical properties of contacting materials on contact stresses and deformations in carbon structural steels caused by a solid particle flow. The existence of three critical states of the material exposed to impact deformation is considered. The first state is characterized by the formation of a plastic flow zone in the surface layer (transition from perfectly elastic to constrained elastic–plastic deformation). The second state is characterized by the exit of this zone to the part surface (transition from constrained elastic–plastic deformation to a free plastic flow, i.e., dynamic indentation). The third state is characterized by the destruction of surface layers due to tensile stresses on the contour of the contact spot values equal to the true tensile strength of the deformable material under tension with allowance for strain hardening. The characteristic values of the dynamic microcontact interaction velocities that correspond to the ranges of the existence of each of the critical state forms were determined. The dominant mechanisms of erosive wear of parts for each of the states (multi-cycle fatigue wear for the first state, low-cycle fatigue wear with an incubation period for the second state, and intensive formation of erosion damage with a minimal incubation period for the third state) were indicated.

Representative volume element-based simulation of multiple solid particles erosion of a compressor blade considering temperature effect

Solid particle erosion is one of the main failure mechanisms of a compressor blade. Thus, characterization of this damage mode is very important in life assessment of the compressor. Since experimental study of solid particle erosion needs special methods and equipment, it is necessary to develop erosion computer models. This study presents a coupled temperature–displacement finite element model to investigate damage of a compressor blade due to multiple solid particles erosion. To decrease the computational cost, a representative volume element technique is introduced to simulate simultaneous impact of multiple particles. Blade has been made of Ti-6Al-4V, a ductile titanium-based alloy, which is impacted by alumina particles. Erosion finite element modeling is assumed as a micro-scale impact problem and Johnson–Cook constitutive equations are used to describe Ti-6Al-4V erosive behavior. In regard to a wide variation range in thermal conditions all over the compressor, it is divided into three parts (first stages, middle stages, and last stages) in which each part has an average temperature. Effective parameters on erosive behavior of the blade alloy, such as impact angle, particles velocity, and particles size are studied in these three temperatures. Results show that middle stages are the most critical sites of the compressor in terms of erosion damage. An exponential relation is observed between erosion rate and particles velocity. The dependency of erosion rate on size of particles at high temperatures is indispensable.

Influence of the shape of quartz sand particles factor on single particle erosion damage

The paper presents data on the influence of aerodynamic factor of quartz sand particles on a single particle erosion damage as a part of investigation of gas-abrasive wear of field equipment steel elements caused by solid particles impact in conditions of sand production of wells. The studies are mainly focused on calculating geometric characteristics of the crater obtained as a result of a single particle impact, such as maximum penetration depth and equivalent diameter of the crater, affected by the shape of the sand grains. The results have shown the significance of experimental and numerical data, including sphericity, roundness and shape factor of particles determination towards further calculation of particles impact parameters.