Erosion Experiments Research Articles

Experimental and numerical study on the high-speed gas-solid nozzle erosion of choke manifold material in high pressure and high production gas well

High pressure difference, high flow rate, and high sand content in throttling manifolds of high-pressure and high-production gas wells make the problems of high-speed gas-solid erosion wear especially prominent. The failure of the throttling manifold is frequent, which is easy to induce overflow, kick, and blowout accidents, aggravates well-controlled risks, and brings safety risks. Therefore, according to ASTM G76–2013, this paper adopts the gas-solid nozzle erosion test method and air jet erosion test rig. The high speed (107 m/s-49 m/s) gas-solid nozzle erosion test of 30CrMo alloy steel was carried out under different inlet pressures (0.06 MPa–0.15 MPa) and impact Angle (15°-90°), and the erosion rate of 30CrMo alloy steel under different experimental conditions was obtained. The erosion rate equation of 30CrMo alloy steel suitable for high-speed solid particle impact is established. Based on the results of erosion experiments, the optimal particle motion model for high-speed compressible flow is constructed. Combined with the discrete phase model (DPM) and gas-solid two-phase coupling calculation method, a three-dimensional CFD erosion model of the “reduced-tuber-nozzle-erosion cavity” was established. The erosion simulation of the gas-solid nozzle of 30CrMo alloy steel, a throttling manifold material, was carried out at different impact angles (15°-90°) and inlet pressure (0.06 MPa–0.15 MPa), and the distribution characteristics of the flow field, particle movement trajectory, impact velocity distribution, and slip characteristics were revealed. The accuracy and reliability of the CFD erosion model and simulation results have been validated by test data.

Deciphering Controls of Pore‐Pressure Evolution on Sediment Bed Erosion by Debris Flows

AbstractPore‐fluid pressure (PP) plays an important role in bed erosion, but the mechanisms that control PP evolution and the resulting feedbacks on flow dynamics are unclear. Here, we develop a general formulation, allowing quantification of the propensity for PP evolution of saturated and unsaturated bed sediments. We conduct erosion experiments by systematically varying grain composition and water content of beds, for investigating effects of PP evolution on flow erosion. With increasing water content, PP shows a slight rise in deforming beds with drained behavior but significant larger rise in undrained beds. Regardless of bed composition, the erosion rate of beds presents a synchronous change tendency with PP evolution due to the loss in basal friction. PP instigates positive feedback that induces a remarkable gain of flow velocity and momentum on wet beds with undrained behavior. Our results help explain observations of volume growth and long run out of debris flows.

Grain size-dependent mechanical response of metal nitride coating under nanoindentation and its sand erosion performance

In this paper, TiN coatings with grain sizes of 54.8 nm, 68.8 nm, 91.5 nm and 136.9 nm was prepared on the aluminum alloy by extending the coating deposition duration. The mechanical performance under nanoindentation and sand erosion were evaluated. The results show that there is a positive correlation between the hardness of the TiN coating and the grain size. Under the shear stress, the primary mechanism governing the mechanical behavior of the TiN coating is grain boundary sliding when the grain size is less than 70 nm. However, when the grain size surpasses 90 nm, the mechanical response shifts towards the emergence of shear bands and lateral cracks. During nanoindentation loading, TiN coatings with different grain size shows amorphous transformation. Sand erosion experiments demonstrate that refining the grain structure enhances the coordination capability of the TiN coating during plastic deformation, leading to a substantial increase in the amount of sand needed to initiate coating cracks. Simultaneously, the augmentation in the quantity of grain boundaries enhances the TiN coating's capacity for coordinating during plastic deformation, ultimately bolstering its resistance to crack propagation and erosion.

Evaluating Effective Particle Size Distributions of Cohesive Sediment under Varying Shear Stress and Bed Configurations in a Rotating Annular Flume

Despite the environmental significance and ecological importance of cohesive sediment (<63 μm), improved knowledge of how effective particle size distributions (EPSDs) change due to flocculation under different conditions of shear stress and bed configuration is required to better understand in situ transport and storage properties and refine existing sediment transport models. Here, a rotating annular flume was used to (i) evaluate EPSDs under different shear stress and bed types (plane-impermeable and -porous gravel bed) for deposition and erosion experiments; (ii) assess flocculation processes with EPSDs; and (iii) compare flume and field EPSDs observations with respect to measured shear stress. While deposition experiments over the impermeable bed led to an EPSD equilibrium in all shear conditions (constant EPSD percentiles), the ingress experiment over the gravel bed resulted in varying EPSDs, and no equilibrium was observed. During the erosion experiment, deposited flocs became coarser due to bed consolidation, and no particle breakage was observed once particles were resuspended. The ingress experiment showed high efficiency in entrapping suspended particles (~95% of initial suspended sediment), and no exfiltration or resuspension was recorded. Flocculation ratios calculated using EPSDs showed negative correlations with shear stress, indicating that increasing flow energy promoted flocculation for flume and field observations. Our results showed that both suspended and bed sediments can flocculate into coarser flocs that, in turn, are preferentially ingressed and stored in the substrate when in suspension. These findings have important implications regarding legacy impacts, as substrate-stored particles can potentially extend the effects of upstream landscape disturbances.

Research on Erosion Effect of Various Submerged Cavitating Jet Nozzles and Design of Self-Rotating Cleaning Device

Submerged cavitating jets can effectively remove marine organisms from ship hulls without damaging the surface paint. To enhance the cleaning efficiency of cavitating jets, the selection of an appropriate nozzle structure and the design of an efficient cleaning device are crucial. In this study, the submerged cavitation effect of different nozzles was analyzed by numerical simulation. The actual cleaning efficacy of the nozzles was confirmed through erosion experiments as well. The simulation and experiment showed that the shear nozzle, absent of a pre-shrinking section and featuring a spherical outlet connected to a diffusion cylindrical section, maintained stable erosion performance at a standoff distance of 30–50 mm. This erosion was primarily attributed to denudation caused by bubble collapse. Based on this shear nozzle, a self-rotating cleaning device was designed and manufactured. A test rig was also established to test the cleaning effect and some parameters of the cleaning device.

A 1-dimensional-two-layer transient drift-flux model for hydraulic transport pipelines: modelling and experiments of bed layer erosion and density wave amplification

Abstract Hydraulic transport pipelines in the dredging, mining and deep sea mining are designed using steady-state methods. However, these methods cannot predict density wave formation. Density waves form a risk for pipeline blockages, therefore there is a need to understand and preferably be able to model the process. The density waves studied in this research are caused by a stationary sediment deposit in the pipeline. This article explores the development of a new transient design model, based on 1-dimensional-two-layer Driftflux CFD. The two layers model the exchange of sediment between the turbulent suspension, and a stationary bed layer, and can therefore model density wave amplification. An empirical erosion-sedimentation closure relationship is applied to model the sediment exchange between the two layers, and is calibrated using experiments. The final model is also validated against a second experiment, specifically for density wave amplification. The experiments and the model show good agreement on the erosion of a stationary bed layer and the growth rate of a density wave and the amplitude of the density wave.

Effect of pineapple leaf and ramie fiber length and weight percentage on the hybrid polymer composites dry sliding wear and air jet erosion studies

AbstractIn this work, pineapple leaf fiber (PALF) and ramie hybrid fiber‐reinforced epoxy composite samples were evaluated for their hardness strength and resistance to dry slide wear and air jet erosion. Primary reinforcement using the hybrid material was chosen from different lengths (10, 15, 20, and 25 mm) and weight percentages (10%, 20%, 30%, 40%, and 50%). The hardness strength of the hybrid composite varied from 74 to 97 Shore D hardness strength. A dry sliding wear test was conducted with the key parameters of load (20, 30, and 40 N), time (20, 10, 7 min), and speed (160, 320, and 479 rpm). By using the data analyzing software, Taguchi optimization method, the key contribution parameters were identified. In the air jet erosion experiment, impact angle (45°, 60°, and 90°), erodent velocity (28, 41, and 72 m/s), and discharge rate (1, 2.5, and 3.3 g/min) parameters were used. Fiber and matrix materials agglomeration effect and bonding behavior were identified by using the scanning electron microscope (SEM) images. The 20 mm length with 30% of the PALF and ramie hybrid fiber‐reinforced composite sample achieved high hardness strength (97 shore D) and created a high resistance toward wear and erosion studies.Highlights Natural plant pineapple leaf and ramie fibers are mixed with an epoxy matrix. Used Taguchi analysis to determine the means and signal‐to‐noise ratios Different weight percentages of the PALF and ramie hybrid composites Dry sliding wear and air jet erosion studies are conducted. Individual parameter contributions were identified.

Surface sediment erosion characteristics and influencing factors in the subaqueous delta of the abandoned Yellow River Estuary

Estuarine deltas play a critical role in the interaction between the ocean and land and serve as the primary location for the deposition of terrestrial organic carbon and pollutants. However, many deltas are increasingly at risk of erosion due to natural processes and human activities. In particular, abandoned estuarine deltas are extremely prone to erosion in the absence of sediment replenishment. The erosion of sediment in these deltas is crucial in comprehending the evolution of delta erosion as it directly impacts coastal geomorphology, ecological environments, geochemical cycling, and carbon sequestration dynamics. Therefore, determining accurately the erosion characteristics of estuarine deltaic sediments is essential for assessing and managing these evolving coastal systems. Therefore, this study conducted erosion experiments on undisturbed sediment samples collected from the subaqueous delta of the abandoned Yellow River Estuary (Old Qingshuigou Estuary) utilizing the UMCES-Gust Erosion Microcosm System. The aim was to reveal the spatial distribution characteristics of sediment erodibility and explore the erosion process, characteristics, and influencing factors of the surface sediments in the area. Erosion characteristics exhibited a spatial distribution pattern of increased erodibility in nearshore sediment and reduced erodibility in offshore sediments. The critical erosion shear stress of surface sediments ranged from 0.2 to 0.68 N/m2, while the erosion rate increased linearly with an increase in erosion shear stress and reached a maximum value of 2.119 g/m2 s, suggesting that nearshore sediments exhibited strong erodibility. Furthermore, the erosion characteristics exhibited a strong correlation with the type of sediment. Silt exhibited surface erosion and Type I erosion (depth-limited erosion), whereas silty sand primarily underwent volume erosion and Type II erosion (steady-state erosion). Particle size characteristics played a crucial role in influencing erosion. Additionally, our results revealed that the effective particle size of sediment aggregates and the scale effect of turbulence were also important factors that affected sediment erosion characteristics. These findings not only enhance our understanding of the erosion characteristics of silty sediments but also provide valuable parameters for sediment transport models in large river deltas such as the Yellow River Delta, thus facilitating the release of buried organic carbon and heavy metals from estuaries.

Analysis of the Sand Erosion Effect and Wear Mechanism of Wind Turbine Blade Coating

The wind–sand climate prevalent in the central and western regions of Inner Mongolia results in significant damage to wind turbine blade coatings due to sand erosion. This not only leads to a decline in power generation but also poses safety risks. This study replicated the wind–sand environment of Alashan and numerically simulated the erosion and wear process of the blade coatings of a 1.5 MW horizontal axis wind turbine under rotational conditions using the DPM model. Additionally, erosion tests were conducted on the operating wind rotor in a wind tunnel. The simulation results demonstrate that sand particle trajectories in the rotating domain are influenced by vortex, incoming wind speed, and sand particle size. For small-sized sand particles, variations in wind speed do not substantially alter the number of particles in contact with the wind turbine blades. However, alterations in the momentum of these particles lead to changes in the impact force on the coating surface. Conversely, the change of wind speed will not only alter the number of large-size sand particles in contact with the wind rotor but also modify the impact force on the coating surface. Furthermore, after impacting the blade, small sand particles continue to move along an approximate helical trajectory with the airflow, while large-size sand particles swiftly rebound. Through statistical analysis of erosion pits on the blade surface after the erosion experiments, it was observed that, in comparison among the leading edge, windward side, trailing edge, and leeward side, the leading edge presents the greatest number of erosion pits, whereas the leeward side has the fewest. Along the spanwise direction, the 0.7R-blade tip segment exhibits the highest count, while the blade root-0.3R section displays the fewest number of pits. The wear morphology of the blade coating was observed from the blade root to tip. The leading edge coating exhibits a range from shallow pits to coating flaking and deeper gouge pits. On the windward side, the coating displays wear patterns varying from tiny cutting pits to cutting marks, and then to gouge pits and coating flaking. Erosion morphology of the trailing edge evolves from only minor scratches to spalling pits, further deepening and enlarging. These research findings provide a basis for the study of zoning-adapted coating materials for wind turbine blades in wind–sand environments.

Responses of soil microbial metabolic limitations to erosion under contrasting soil types and management practices

AbstractSoil microbial metabolism plays an important role in supporting soil services and functionalities but is usually restricted by the availability of soil nutrients. Although soil microbial metabolism limitation (SMML) has been widely addressed with regard to various driving factors, its response to erosion has not been examined but is urgently needed given the important influence of erosion on global environments. To understand how erosion affects SMML and whether erosion's effect varies with tillage practices and soil types, we conducted a simulated erosion experiment to compare eroded and noneroded plots with contrasting soil types (Mollisol vs. loess soils) and managements (conventional tillageversusno‐tillage in plots with crops versuswithout crops). We measured soil extracellular enzymatic activities and quantified SMML with extracellular enzymatic stoichiometry models. In both soils, the microbes were limited by carbon (C) and phosphorus (P), but not by nitrogen, and microbial C and P limitations were greater in Mollisol than loess soils. For the Mollisol, erosion significantly increased the relative C limitation, whereas the presence of crops eliminated this increase. For the loess soils, erosion enhanced the relative C limitation regardless of crop presence and tillage management. Erosion consistently increased microbial P limitation in plots with crops, with greater effects under no‐tillage (+2.9%) compared to conventional tillage (+0.7%) conditions regardless of soil type (p < 0.05). In plots without crops, microbial P limitation was increased by erosion under no‐tillage (+2.1%) but was decreased under conventional tillage (−5.6%) (p < 0.05). Additionally, conventional tillage exacerbated microbial C limitation but alleviated microbial P limitation. These results indicated that erosion shifted microbial C and P limitations depending on soil type, tillage practice and the presence of plants, highlighting the importance of considering all these factors when assessing soil microbial metabolic limitation at various spatial scales.

Experimental and numerical investigation of hydro-abrasive erosion in the Pelton turbine buckets for multiphase flow

Sediment erosion-corrosion is a critical threat to the safe operation of hydro turbines, which may lead to component damage or even complete failure of the turbine. A lack of understanding of the mechanism of sand erosion is a barrier to developing an erosion model to exactly quantify sand erosion in the Pelton turbine. The preeminent objectives of this research work are to determine parameters that influence sand erosion, identify erosion-prone areas in Pelton turbine buckets, quantify the erosive wear experimentally and numerically, determine the impact of erosive wear, and analyze the microscopic mechanism of erosion. Five Pelton buckets made of aluminum, carbon steel, stainless steel, polylactic acid (PLA), and acrylonitrile butadiene styrene (ABS) were used to perform erosion experiments under two-phase, solid-liquid flow conditions. Multi-layer paint modelling technique was used to identify erosion-prone areas. Optical profilometry was used to perform surface roughness analysis and Scanning Electron Microscopy was used to evaluate the microscopic degree of damage due to erosive wear in the Pelton bucket. Mass loss and thickness reduction analyses were performed to quantify the erosive wear. The erosion rates of aluminum, carbon steel, stainless steel, and ABS were 190 %, 86.73 %, 48.79 %, and 5.61 % higher, respectively, compared to PLA and both PLA and ABS demonstrated exceptional resistance.

Mechanical relationship between compressive strength and sulfate erosion depth of basalt fiber reinforced concrete

To mitigate the restraining effect of basalt fiber on the sulfate erosion damage in basalt fiber reinforced concrete, sulfate erosion experiments were carried out on both ordinary concrete and basalt fiber reinforced concrete. Changes in concrete strength in relation to sulfate erosion depth under various sulfate solutions and erosion ages were recorded. The mechanical relationship between the compressive strength and sulfate erosion depth was proposed. The results showed that the inflection point on the strength-erosion age curve for basalt fiber reinforced concrete appeared significantly later than that in ordinary concrete, indicating that basalt fiber can delay sulfate erosion and enhance concrete durability. Using the measured sulfate erosion depth, remaining compressive strength can be predicted.

Contribution of local erosion enhanced by winds to sediment transport in intertidal flat

Field work combining in-situ mooring and erosion experiments was conducted in the intertidal flat of Asan Bay to reveal the relationship between sediment erodibility and external forcing and the contribution of local erosion to sediment transport. A total of 25 tidal cycles occurred during the mooring period with 6-h submergence and 5.7-h air exposure. The erosion rate (E) for sediment bed during air exposure was 0.007 g m−2 s−1, which was 36% of E (0.019 g m−2 s−1) during submergence. Although the sediment bed was influenced by consolidation during air exposure, the erodibility of the submerged bed was closely associated with the unconsolidated deposits of sediments newly supplied from tidal channel and bed shear stress (τcw) induced by current-wave interactions. In particular, τcw could be enhanced by strong winds, which depended on the ratio (Hs/h) of significant wave height and water level, directly disturbing the sediment bed. Under weak winds (Hs/h < 0.06), the newly deposited sediments with high erodibility increased the bed elevation. A small amount of the sediment bed was eroded (E: 0.006 g m−2 s−1), as a floc erosion, with a slight decrease in suspended sediment concentration (SSCT). This increased the contribution (57.2%) of eroded sediments to SSCT. Under strong winds (Hs/h > 0.06) with enhanced τcw, meanwhile, the erodible sediment in the bed was depleted accompanied by a decrease in bed elevation. A large amount of sediment bed was eroded (E: 0.025 g m−2 s−1), as a surface erosion, resulting in the rapid increase in SSCT and the enhanced seaward sediment flux. The sediments eroded from the bed were supplied to water column accounting for 86.8% of SSCT. This suggests that seaward sediment transport under strong winds could be caused by surface erosion shifting from floc erosion in the intertidal flat.

Benthic sediment disturbances by episodic human-controlled discharge in an altered estuary

In the Geum River, a representative altered estuary, in-situ mooring and erosion experiments were conducted to reveal the effects of human-controlled discharge on benthic sediment disturbances. The strong discharge through the estuarine dam increased the current velocities within the benthic boundary layer (BBL) up to 79% and 153% during spring and neap tides, respectively. During the discharge period, the suspended sediment concentration in BBL was five times higher than that during the non-discharge period. During the flood phase, a critical shear stress for erosion (τce) was in the range of 0.1278 to 0.1391 Pa. Immediately after the ebb phase with strong discharge, τce increased to 0.1848 Pa, and the erosion rate (E) decreased from 33.73 to 14.81 mg m−2 s−1. The repetition of human-controlled discharge removed the erodible sediments within BBL, exposing the underlying consolidated sediment bed with low E and high τce. The results suggest that an altered estuary is vulnerable to benthic sediment erosion under combined natural and anthropogenic forcings.

Modelling of physical sputtering properties during tungsten fuzz growth under various impact energies on NAGDIS-II

Fibre-like nanostructure named fuzz can form on tungsten (W) surface under the irradiation of helium (He) plasma. While the W fuzz growth can be suppressed by the bombardment of energetic He particles. The experiments of tungsten fuzz growth and erosion exposed by He plasma with impact energies in the range of 200 ∼ 500 eV have been conducted on the linear divertor simulator NAGDIS-II. To study W physical sputtering properties during fuzz growth on NAGDIS-II, three-dimensional kinetic Monte Carlo code SURO-FUZZ has been upgraded by including the migration of W adatoms and the deposition of sputtered W particles. By means of the renewed SURO-FUZZ, dedicated simulations of W fuzz growth and erosion under various He impact energies have been performed to reproduce the NAGDIS-II experiments. The simulated fuzz layer thicknesses under erosive regimes show a good agreement with the measurements on NAGDIS-II. The W net physical sputtering yield on W fuzzy surfaces increases with He impact energy according to SURO-FUZZ modelling. Further, the relative W net physical sputtering yields of the fuzzy surface to the smooth surface (Yfuzz/Ysmooth) have been studied under different He impact energies, which reveals that the decay trend of Yfuzz/Ysmooth is mainly dependant on the fuzz layer thickness.

Experimental Research on Erosion Characteristics of Ecological Slopes under the Scouring of Non-Directional Inflow

Considering environmental sustainability, ecological embankments are often adopted in rivers, which benefit both the erosion resistance and the ecological balance of the bank. In this paper, the effectiveness of different types of dominant grass species in ecological slope protection and their impact mechanisms, as well as the impact of non-directional inflow on erosion characteristics, were investigated. Based on the principle of similarity theory in hydraulic modeling and the characteristics of flood erosion in riverbanks, a test model system for hydraulic ecological simulation was designed, including a vegetation bank slope and channels. Three types of dominant grass species were selected, and 12 series of erosion experiments were conducted in the grassed slope of the test model. Three types of root–soil composites and a reference plain soil were involved in the tests, and soil mechanical indicators such as shear strength were collected. Experimental results show that root–soil composite is a special elastic–plastic material, which provides additional cohesive force to the soil due to its root consolidation and reinforcement effects, Δc. The shear strength index reflecting soil cohesion was increased by 15% to 20%. The primary factor affecting slope erosion is the flushing velocity, and both the average erosion depth and the unit soil erosion loss present an exponential function with respect to this factor, while presenting a linear function with the angle of incoming flow. Compared with the plain soil slope, the ecological slope could decrease erosion significantly. The sand loss of the ecological slope is only 50~60% that of the plain soil slope as the flushing velocity is 3–4 m s−1. In vertical flushing, the sand loss in the plain soil slope is 1.73–2.43 times that of the ecological slope. This research might provide technical support for the anti-scourability design of the ecological embankment.

Arbuscular mycorrhizal fungi alleviate erosional soil nitrogen loss by regulating nitrogen cycling genes and enzymes in experimental agro-ecosystems

Nutrient losses from agricultural ecosystems are increasingly threatening global environmental and human health. Although arbuscular mycorrhizal (AM) fungi have the potential to regulate soil nitrogen (N) loss by enhancing plant uptake and soil particle immobilization, the microbial mechanism behind such mycorrhizal effect is unknown. Herein, by conducting a simulated erosion experiment, we compared the effects of exogenous AM fungal inoculation (Funneliformis mosseae) on the gene abundances and enzyme activities of N-cycling processes, and associated such effect to N uptake and loss. The experiment was composed of combinations of two AM fungal treatments (control vs. AM fungal inoculation), two crops (maize vs. soybean) and two slopes of the plots (6° vs. 20°). The experimental plots subjected to natural rainfalls to simulate the erosion events. We showed that the effects of AM fungi were greater in the maize soils than in the soybean soils. In the maize soils, AM fungi increased the abundances of N-fixing (+81.1 %) and nitrifying genes (+200.7 %) and N cycling enzyme activity (+22.3 %). In the soybean soils, AM fungi increased the N-fixing gene abundance (+36.9 %) but decreased the abundance of nitrifying genes (−18.9 %). The abundance of N-fixing gene was positively correlated with N uptake but negatively correlated with N loss. Additionally, AM fungi enhanced the effects of mycorrhizal colonization and moisture but decreased the effects of nutrients on soil microbial metrics related to N-cycling processes. Therefore, AM fungal inoculation enhanced N uptake and reduced N loss by increasing N-fixing gene abundance, and that AM fungi should be preferably used for the low N environments or for the ecosystems highly limited by or competing for N.

Solid-liquid multiphase flow and erosion in the energy storage pump using modified drag model and erosion model

In order to achieve the carbon neutrality, the wind and solar power have greatly developed in recent years, which leads to a challenge of unpredictability and intermittence for the power grid. A new concept of energy storage pump station is proposed, which uses the large pump to store water from the downstream reservoir to the upstream reservoir in cascade hydropower stations, and consumes the electricity from wind and solar power. However, due to the high sediment content of rivers in China, erosion is a critical issue that damages components and shortens the operational life of energy storage pumps. In this work, an improved calculation model based on modified drag model and modified erosion model is established to investigate the solid-liquid two-phase flow and erosion characteristics in an energy storage pump. In the calculation model, a modified drag model by considering the effect of turbulence intensity is proposed, and a modified erosion model by considering the effect of particle Stokes number is proposed. An erosion experiment on a 90° elbow pipe is used to validate the accuracy of the improved calculation model, and the maximum error of erosion rate between experiment and calculation is 1.86 %. Then, solid-liquid flow and erosion in a centrifugal pump with the specific speed of 102 are numerically calculated under particle sizes of 0.01 mm, 0.05 mm, 0.1 mm, 0.25 mm, 0.5 mm, 0.75 mm and 1 mm, respectively. Results show that particles tend to accumulate at the hub and blade pressure side as particle size increases, which results in a rise in non-uniformity of particle distribution in impeller. Meanwhile, the non-uniformity of erosion in impeller strengthens with particle size increase, and erosion in impeller under particle size of 1 mm is 1245 times more than that under particle size of 0.05 mm. A new evaluation method of effect level of parameter on erosion of a centrifugal pump by using Stp = 1 is proposed. When Stp < 1, particle impact velocity is the primary factor on erosion, and the average erosion rate decreases with particle size increase. When Stp > 1, the particle number impacting the wall is the primary factor on erosion, and the average erosion rate increases with particle size increase.

Modeling the response of a field probe for nondestructive measurements of the magnetic susceptibility of soils

AbstractNondestructive volume magnetic susceptibility measurements (MS) from the surface do not provide information about the depth distribution of a magnetic material or about the amount of magnetic material. We have developed a model that can be used to predict the volume magnetic susceptibility from the surface for a given (known or hypothesized) stratification of the magnetic layers in the soil profile. The measurements were performed with the MS2D Bartington sensor. The antenna signal from the MS2D probe decreases rapidly with depth. We show that the relative decrease in MS depends not only on the concentration of the magnetic tracer, but also on the distribution of the magnetic tracer in the soil profile. The decrease in sensitivity was fitted with a double exponential function. The function was implemented in a newly developed MagHut model. The MagHut model is a tool that can be used for forward modeling of the volume magnetic susceptibility when the tracer distribution in the soil profile is known. The model was successfully calibrated and validated with the measured data and with data from the literature. The Nash–Sutcliffe coefficients for goodness of fit were above 0.99 in all cases. MagHut can help interpret MS mapping results or it can be used to optimize amount and placement of the magnetic tracer for soil erosion experiments. However, the MagHut tool is only limited to the top 10 cm of the soil profile and cannot replace, but only complement, the standard procedure of occasional soil profile sampling and laboratory mass MS measurements.

Parametric analysis of erosion wear of sponge iron slag-filled ramie–epoxy composites using Taguchi and preference selection index methods

The present work reports on the development of a novel set of ramie–epoxy composites filled with sponge iron (SI) slag (0–30 wt.%) and on their response to solid particle erosion wear under different test conditions. SI slag is a by-product generated during the processing of SI to steel in arc or induction furnace. While these composites are fabricated using the conventional hand layup technique, the erosion tests are carried out using an air jet erosion tester following ASTM G76 test standard as per Taguchi's L27 orthogonal array. Mechanical characterization of ramie–epoxy composites suggests that the incorporation of SI slag improves their tensile strength by about 52%, flexural strength by 10% and micro-hardness by about 30%. A parametric appraisal of the erosion response carried out using Taguchi method reveals that the filler content, impact velocity and impingement angle are the most significant control factors influencing the erosion rate of these composites. The individual effects of different factors in wider ranges (impact velocity 25–125 m/s, filler content 0–30 wt.% and impingement angle 30–90°) are ascertained by conducting steady-state erosion experiments in controlled conditions. Preference selection index method, which is an effective multi-criteria decision-making tool is used to select the best candidate among all composites based on different physical, mechanical and wear test results. It is found that the composite with 30 wt.% SI slag content displays the optimal combination of properties. The worn morphologies of the eroded surfaces of the composites are studied and analyzed using electron microscopy to identify possible mechanisms causing the wear loss.