Erosion Angle Research Articles

Study on the resistance of basalt fiber concrete to erosion of building structure by wind gravel flow

Concrete structures in the windy regions of the Gobi face constant erosion from wind gravel flow, leading to severe surface damage and significantly reduced durability. This paper investigates the erosion resistance of basalt fiber (BF) concrete under various erosion conditions using the air-flow sand injection method. The results indicate that adding 0.15 % BF to concrete reduces its erosion rate by 20.7–21.5 % compared to concrete without BF. Therefore, a BF content of 0.15 % (BF15) provides optimal erosion resistance for the concrete. The correct amount of BF bonds tightly with the cement mortar, forming a mesh structure inside the concrete that absorbs the kinetic energy of gravel impacts. The concrete erosion process can be divided into an early accelerated phase and a later stabilized phase. Throughout these phases, the erosion rate of concrete increases with the erosion angle (EA), erosion wind speed (EWS), and gravel flow rate (GFR). In particular, the erosion rate of BF15 concrete increased by 35.6–46.4 mg/cm² when the EA changed from 15° to 90°. Notably, surface damage from low-angle erosion mainly consists of cut scratches, while high-angle erosion primarily results in erosion pits. As the grain size of the eroded gravel increases, the erosion rate of the concrete decreases. However, when a single large gravel particle impacts the concrete, it creates a larger and deeper erosion pit. Furthermore, the erosion rate of BF concrete exhibits a strong negative linear correlation with its mechanical properties, with an R² value exceeding 0.88. Moreover, erosion reduces both compressive and splitting tensile strengths of concrete. For BF15 concrete, however, the decreases are minimal: compressive strength drops by just 1.2 MPa, and splitting tensile strength decreases by only 0.2 MPa. Building on Bitter and Neilson’s theoretical erosion model, an improved erosion model for BF concrete has been developed under wind gravel flow. This model incorporates the BF mixing factor and particle size function while considering other erosion parameters comprehensively. The enhanced model provides a theoretical foundation and scientific basis for safeguarding concrete structures in Gobi wind-prone regions.

Preparation of protective coatings for the leading edge of wind turbine blades and investigation of their water droplet erosion behavior

The damage caused by rain droplet erosion to the leading edge of wind turbine blades is extremely severe. To reduce this issue, in this study, hydroxyl-terminated polybutadiene (HTPB) and isophorone diisocyanate (IPDI) were used as the polyurethane (PU) polyol and curing agent, respectively, to prepare a PU coating with a high resistance to water droplet erosion (WDE) for the protection of the leading edge of wind turbine blades. The effect of n (–NCO):n (–OH) (R-value, n is the molar ratio) on the mechanical properties and WDE resistance of PU coatings, the relationship between the two performances, and the influence of the erosion conditions on the WDE behavior were investigated for the first time. The results show the existence of a correlation between the mechanical properties (hardness, impact, flexibility, and tensile strength) and WDE resistance of the coating. While, a better abrasion resistance is found not to result in a better WDE resistance. The PU coating with an R-value of 1.2 shows an optimal WDE resistance in both atomization and jet erosion experiments. In atomized droplet erosion (ADE) experiments, the change in erosion velocity accelerates the incubation period of coating erosion damage and increases the erosion rate. In jet droplet erosion (JDE) experiments, the damage to the coating is closely related to the erosion angle, reaching a maximum at an impact angle of 60°. Furthermore, in the ADE experiments, various erosion morphologies, such as pits, grooves, cracks, and stepped texture, are observed on the damaged coating surface. While, regarding the JDE experiments, holes, grooves, and cracks are observed. Such damage is caused by the combined effects of water hammer pressure, lateral jets, and local permeation.

Specific Erosion Resistance Behaviour of Cold Forged and Angular Extruded Aluminium.

Aluminium finds wide application in mechanical engineering due to its low density and corrosion resistance. In this research, aluminium was subjected to two different metal forming technologies-cold forging (upsetting) and equal channel angular pressing (ECAP)-to obtain improvement in its exploitation properties. Parallel to changing mechanical properties by using these two processes, there was a change in the microstructure of the material. The resulting microstructures were examined using an optical microscope. A different treated aluminium was subjected to erosion wear in various time intervals. Wear testing was conducted for two different impingement angles causing abrasive wear and impact wear. The erosion mechanisms were examined by scanning electron microscopy. These results showed that there is no statistically significant difference in erosion wear for different states at the same impingement angle. However, the difference is noticeable at different wear angles. The significance of the difference in wear of the samples treated with the forging and ECAP techniques was validated by statistical analysis with tests of different sensitivities. The results of the t-test showed that ECAPed samples present a statistically significant difference in the loss of mass due to variations in erosion angle during the 30, 45, and 60 min wearing. A substantial difference in the change in sample mass is also visible for the forged state worn for 60 min.

Erosion-corrosion behavior of Ni-Al-Cu coating on nickel-aluminium bronze alloy in 3.5 wt% NaCl solution

A Ni-Al-Cu coating was prepared on NAB alloy through electroplating and heat treatment, and the erosion-corrosion behaviors were investigated. The results demonstrated that Ni-Al-Cu coating exhibited higher erosion resistance compared to NAB alloy, with an average reduction of 63 % in material removal rate (MRR). It was revealed that deformation and cracks were observed in NAB, with loss of hard κ and β phases alongside deformation of ductile α phase. Meanwhile, Ni-Al-Cu coating experienced fatigue delamination and grain disintegration due to alternating stress. Taguchi design method showed that increasing flow velocity and sand concentration could enhance the intensity of gravel impact, while changes in the erosion angle affected gravel impact modes and energy transfer, thereby impacting corrosion performance. Additionally, empirical equations for the material removal rate were derived through regression analysis, which became possible to predict the MRR under different influencing factors and assess the erosion-corrosion resistance of materials.

Study on preparation and anti-sand erosion performance of thick DLC coating combined with FCVA deposition and HVP technology

To address the compatibility issues between the hardness and thickness of DLC coatings and to improve the erosion resistance of engine blades, a thick DLC coating was prepared using a combination of filter cathode vacuum arc (FCVA) deposition technology and high voltage pulse (HVP) technology. The prepared thick DLC coating exhibits low residual stress (1.79 ± 0.087 GPa) and high C-sp3 content (70.13 %), with a thickness and hardness of 18.46 μm and 51.07 ± 0.23 GPa, respectively. The results of anti-sand erosion tests indicate that the mass loss rates of DLC coating at the erosion angles of 45° and 90° are 4.44 × 10−3 mg/g and 1.99 × 10−2 mg/g, respectively. The good erosion resistance of thick DLC coatings is attributed to the consumption of residual impact energy by carbon cluster structures, which prevents the generation and propagation of cracks. Therefore, the thick and super-hard DLC coatings can be prepared by combining FCVA deposition technique with HVP technique, which has great potential applications in the aerospace industry.

Designing sandwich-zigzag multilayered TiN coatings for corrosion-erosion coupling damage protection

Coatings are utilized to enhance the surface properties of materials. This study aimed to modify the TiN coating with a novel sandwich-zigzag intermediate layer and delve into the intricate damage mechanisms under harsh corrosion-erosion coupling environments. Due to the infiltration of NaCl into the coating and the subsequent formation of TiO2, the sandwich-zigzag TiN coatings exhibited a reduction in mechanical behavior and erosion resistance when exposed to salt spray at 550 °C for 50 h. Moreover, the erosion rates of the as-corroded TiN coatings displayed an opposite trend compared to that of the as-deposited coatings, showing that the erosion rate was highest at the erosion angle of 30°. Nevertheless, the presence of the zigzag-TiN intermediate layer benefited the coating by preventing stress accumulation and heterogeneous interface. This ultimately improved the erosion resistance of the coatings by more than 2 times at universal erosion angle compared to that of the substrates under the synergistic effects of corrosion and erosion.

Studies on air jet erosion behavior of plasma-sprayed Cr2C3 coatings on Al6061 alloy

This study assesses the efficacy of plasma-sprayed Cr2C3 coatings on AA6061 aluminum alloy in reducing erosion at different angles (30, 60, and 90°). The experimental setup involved maintaining a distance of 80 mm between the components, feeding the powder at a rate of 55 g/min, and applying a current density of 460 amps. Weight loss measurements and surface morphology analyses were performed using scanning electron and confocal microscopy. The findings suggest that the Cr2C3 coating significantly improves erosion resistance when compared to specimens without any coating. The erosion angle had a significant impact on the performance of the coating. The coating experienced the least weight loss at an angle of 30° (28.45 g), followed by increased losses at angles of 60° (30.34 g) and 90° (34.2 g). These findings emphasize the significance of the impact angle in determining the severity of material removal.

Study on the Shear Strength and Erosion Resistance of Sand Solidified by Enzyme-Induced Calcium Carbonate Precipitation (EICP).

Sand solidification of earth-rock dams is the key to flood discharge capacity and collapse prevention of earth-rock dams. It is urgent to find an economical, environmentally friendly, and durable sand solidification technology. However, the traditional grouting reinforcement method has some problems, such as high costs, complex operations, and environmental pollution. Enzyme-induced calcium carbonate precipitation (EICP) is an anti-seepage reinforcement technology emerging in recent years with the characteristics of economy, environmental protection, and durability. The erosion resistance and shear strength of earth-rock dams solidified by EICP need further verification. In this paper, EICP-solidified standard sand is taken as the research object, and EICP-cemented standard sand is carried out by a consolidated undrained triaxial test. A two-stage pouring method is adopted to pour samples, and the effects of dry density, cementation times, standing time, and confining pressure on the shear strength of cemented standard sand are emphatically analyzed. The relationship between cohesion, internal friction angle, and CaCO3 formation was analyzed. After the optimal curing conditions are obtained through the triaxial shear strength test, the erosion resistance model test is carried out. The effects of erosion angle, erosion flow rate, and erosion time on the erosion resistance of EICP-solidified sand were analyzed through an erosion model test. The results of triaxial tests show that the standard sand solidified by EICP exhibits strain softening, and the peak strength increases with the increase in initial dry density, cementation times, standing time, and confining pressure. When the content of CaCO3 increases from 2.84 g to 12.61 g, the cohesive force and internal friction angle change to 23.13 times and 1.18 times, and the determination coefficients reach 0.93 and 0.94, respectively. Erosion model test results indicate that the EICP-solidified sand dam has good erosion resistance. As the increase in erosion angle, erosion flow rate, and erosion time, the breach of solidified samples gradually becomes larger. Due to the deep solidification of sand by EICP, the development of breaches is relatively slow. Under different erosion conditions, the solidified samples did not collapse and the dam broke. The research results have important reference value and scientific significance for the practice of sand consolidation engineering in earth-rock dams.

Erosion model of silicon carbide ceramics and YW3

In this study, an erosion model of silicon carbide ceramics and YW3 was established by combining experimental and numerical simulation data. This model can be applied for the prediction of erosion in natural gas equipment and transportation systems and also provides ideas for the establishment of erosion models. The erosion model was established by using quartz sand, brown corundum, and glass beads as abrasive materials, and then the accuracy of the erosion model was confirmed by numerical simulations. The results showed that when the abrasive was quartz sand, brown corundum, or glass beads, the erosion angle at which the maximum erosion of silicon carbide and YW3 occurred was related to the type of abrasive. When the abrasive was quartz sand, brown corundum, and glass beads, the velocity index n of silicon carbide was 3.24, 3.66, and 3.32, respectively, and the model constant k was 4.1959 × 10−11, 3.6436 × 10−11, and 4.1838 × 10−11, respectively. The velocity index n of YW3 was 2.29, 2.41, and 1.87, respectively, and the model constant k was 2.6176 × 10−7, 3.0017 × 10−7, and 3.1040 × 10−7, respectively. When the test results were compared with the numerical simulation results, the maximum error for silicon carbide was 6.59%, 7.71%, and 9.25%, respectively, and the maximum error for YW3 was 8.78%, 9.51%, and 5.97%, respectively. Finally, the erosion model of silicon carbide ceramics and YW3 was established via a large number of experiments and numerical simulations. When the target material and abrasive material are the same, it can be directly used for erosion prediction and structure optimization of natural gas equipment. Meanwhile, this paper provides a new idea for the establishment of gas–solid two-phase erosion model, and when the abrasive material and target material change, a new erosion model can be established according to the idea of this paper.

Tribological properties and solid particle erosion wear behavior of Al2O3-13 wt%TiO2/Al2O3-PF composite coatings prepared on resin matrix by supersonic plasma spraying

Resin materials feature exceptional physical properties and inexpensive cost, but unfavorable surface characteristics, such as low wear resistance and poor erosion wear performance, render them tough to satisfy greater demands. The potential option is to prepare supersonic plasma sprayed Al2O3-13 wt%TiO2/Al2O3-phenolic resin (AT13/Al2O3-PF) coating on the surface of the resin matrix. AT13 feedstocks are classified into two types: Al2O3-13 wt%TiO2 powder prepared by the agglomeration granulation process (AT13-1) and the mixture of spherical Al2O3 and TiO2 (approximately 13 wt%) powder (AT13-2). The effect of component dispersion on mechanical and tribological characteristics of coatings was thoroughly investigated, as well as the solid particle erosion wear behavior of coatings. The results illustrated that the evenly dispersed TiO2 phase in AT13-1 coating was prone to homogenize the coating structure, resulting in better tribological characteristics than AT13-2 coating, although erosion wear performance was inferior to AT13-2 coating. The wear rate of AT13-1 coating was 1.36 × 10−5 mm3 (N m)−1, which was 1/21 times that of AT13-2 coating. At the 60° erosion angle, the high porosity of AT13-1 coating resulted in hard phase cracking or hard phase debonding. The high microhardness of AT13-2 coating reduced erosion wear at the 90° erosion angle.

Prediction of gas–solid erosion wear of bionic surfaces based on machine learning and unimodal intelligent optimization algorithm

Solid particle erosion wear is an inevitable phenomenon in industrial production, with erosion removal mass serving as a crucial metric for assessing the wear rate per unit area on the impacted surface. Developing predictive models to estimate the degree of mass removal is crucial for effectively controlling, evaluating, and preventing severe damage resulting from solid particle erosion wear. In this study, we constructed a comprehensive dataset comprising smooth and bionic surfaces, encompassing inner, outer, and planar surfaces. The dataset was used in a multifactorial erosion experiment, considering adjustable erosion angles, solid particle incident gas velocities, and solid particle diameter sizes. Through visualization and analysis of the obtained dataset, we identified optimal scenarios for bionic surface erosion resistance, offering insights for structural design against bionic erosion resistance. Furthermore, we compared machine learning algorithms to address the prediction problem, resulting in the selection of the best-performing regression algorithm, SVR (Support Vector Regression). Additionally, we compared the performance of other advanced intelligent optimization algorithms using unimodal benchmark functions, finding that HHO (Harris Hawks Optimization) emerged as the optimal choice for unimodal optimization. Building on HHO, we developed the IHHO (Improved Harris Hawks Optimization)-SVR model, using experimental data from erosion tests as the training dataset. This model can predict gas–solid two-phase flow erosion patterns, encompassing various wall types, solid particle sizes, solid incident gas velocities, and impact angles. Due to its robustness and rapid prediction capabilities, the model is expected to serve as a cost-effective tool for predicting erosion removal mass in gas–solid two-phase flow scenarios.

Study of erosion wear to concrete by different gravel particle sizes: Laboratory test and numerical simulation

Concrete bridge piers face relentless erosion from Wind Gravel Flow (WGF) in Lanzhou–Xinjiang High–Speed Railway, resulting in pronounced wear on their surfaces, which could potentially induce additional structural defects. This study aims at the erosion wear performance and its corresponding damage mechanisms in concrete under WGF, using the airborne sandblasting method as a tool for this analysis. The study suggests that the Concrete Erosion Rate (CER) intensifies parallel to increases in both erosion angle and wind speed. Low angle erosion predominantly causes surface damage through cutting, while high angle erosion results in erosion pits and cracks. Notably, CER initially rises but eventually stabilizes with varying erosion times. A widened gravel particle size interval leads to a consistent reduction in the CER, but it concurrently heightens the likelihood of erosion caused by individual gravel particles on the concrete surfaces. An expanded gravel particle size interval results in a considerable increase in both the size and depth of erosion pits on the concrete surface. On the other hand, a narrowed particle size interval contributes to a significant upsurge in the number of erosion pits, causing the CER to diminish as the particle size interval increases. A novel model adapted for concrete exposed to the windy conditions of the Gobi has been developed. The model’s accuracy has been substantiated via numerical simulations, which illustrates that an uptick in erosion wind speed considerably boosts the airflow velocity around the concrete sample. In contrast, the pressure distribution on the surface steadily decreases from the center to the periphery. As erosion wind speed increases, airflow velocity and surface pressure around the concrete specimen rise significantly. Furthermore, the surface pressure of concrete increases with a broader gravel particle size interval. In conclusion, this study provides a strong scientific and theoretical underpinning for the protection of concrete bridge piers in the wind–prone Gobi regions.

Effect of bias voltage on the erosion performance of TiAlSiN coatings on TC6 substrate by high power impulse magnetron sputtering

TiAlSiN coatings were deposited on TC6 substrates by high power impulse magnetron sputtering at various bias voltages for the improvement of titanium alloy anti-sand erosion performance. The effect of bias voltage on the composition, microstructure and mechanical properties were investigated by X-ray photoelectron spectroscopy, X-ray diffractometer, transmission electron microscopy, scanning electron microscopy, Rockwell-C indentation, scratch testing and nano nanoindentation. The erosion performance was evaluated at the impingent angles of 30° and 90° respectively in a sand blasting tester. With the application and increase in bias voltage, the discharge current increases from ∼87 A to ∼210 A. The coatings exhibit face center cubic structure, mainly composed of the (Ti,Al)N nanocrystallites and Si3N4 matrix. The preferred orientation shifts from (200) to (220) in the range of 0∼−150 V, but goes back to (200) at −200 V. The surface nodular defects and deposition rate are gradually reduced, yet the sectional structure becomes much denser. The residual stress is compressive and continually grows, whereas the adhesion strength, hardness (H), Young's modulus (E) and H/E ratio gradually increase before decreasing, arriving at maximum values of ∼68 N, ∼37.53 GPa, ∼339.9 GPa and 0.11 respectively at −150 V. The erosion resistance of the TiAlSiN coatings is consistent with these mechanical changes at various bias voltages and is also optimal at −150 V, which is ∼14 times that of TC6 substrate. The failure mechanism comes from coating brittleness nature, fractured chips and microcracks, regardless sand erosion angles, yet the driving forces are different.

Morphological damage to tungsten eroded by abrasive water jet

Abrasive water jet is a promising method for processing rolled tungsten plates, which are considered the most promising plasma-facing material in fusion devices. To investigate the erosion of tungsten due to the abrasive water jet, we conducted erosion tests and numerical simulations. We examined the morphological characteristics of the tungsten erosion damage. An erosion model was developed by coupling smoothed-particle hydrodynamics with the finite-element method to simulate tungsten erosion. The mechanism behind the morphological damage characteristics of tungsten was analyzed. Our findings reveal that as erosion depth increases, the kinetic energy of the abrasive particles decreases while the erosion angle increases. The erosion damage to tungsten transitions from brittle fracture induced by microcutting and microplowing to impact deformation. As a result, the erosion section's morphology deteriorates, exhibiting strips from the cutting process, increasing both the trailing angle and surface roughness. The morphological damage characteristics of tungsten are intricately linked to the abrasive particles' motion. Therefore, by altering the motion characteristics of these particles, the erosion section's quality can be enhanced. This research offers valuable insights for enhancing the quality of tungsten sections processed by abrasive water jets in fusion devices.

Study on Erosion Behavior of Laser Wire Feeding Cladding High-Manganese Steel Coatings.

High-manganese steel (HMnS) coating was prepared using laser wire feeding cladding technology. Erosion damage behavior and erosion rate of both the HMnS coating and the HMnS substrate were investigated at room temperature using an erosion testing machine. SEM/EDS, XRD, EPMA, and microhardness analyses were used to characterize the cross sections of the coating and matrix, as well as the morphology, phase composition, and microhardness of the eroded surface. The phase composition, orientation characteristics, and grain size of the eroded surfaces of both the coating and substrate were examined by using the EBSD technique. The erosion mechanism under different erosion angles was revealed. By analyzing the plastic deformation behavior of the subsurface of the HMnS coating, the impact hardening mechanism of the high-manganese steel coating during the erosion process was investigated. The results demonstrated that the HMnS coating, prepared through laser wire feeding cladding, exhibited excellent metallurgical bonding with the substrate, featuring a dense microstructure without any cracks. The erosion rate of the coatings was lower than that of the substrate at different erosion angles, with the maximum erosion rate occurring at 35° and 50°. The damage to the coating and substrate under low-angle erosion was primarily attributed to the micro-cutting of erosion particles and a minor amount of hammering. At the 90° angle, the dominant factor was hammering. After erosion, the microhardness of both the coating and substrate sublayer increased to 380HV0.3 and 359HV0.3, respectively. Dendrite segregation, refined grains, low-angle grain boundaries, and localized dislocations, generated by laser wire feeding cladding, contributed to the deformation process of HMnS. These factors collectively enhance the hardening behavior of HMnS coatings, thereby providing excellent erosion resistance.

Investigation of erosion wear performance and mechanism of mold materials

Abstract The surface of an injection mold is prone to erosion and wear under the impact of the filler during plastics injection molding, which leads to premature failure of the mold. The mechanism of erosion and wear of a filler on the mold has not been clarified yet. A numerical technique was employed to simulate the erosion and wear process, and the influence of environmental parameters and particle characteristics, such as erosion velocity, erosion angle, temperature, and particle shape were studied. The results showed that the erosion velocity and erosion angle are important factors that affect erosion and wear. Finally, the relationship between change of particle energy and erosion and wear of the material is studied from the perspective of energy.

Experimental and simulation analysis of erosion law of crude gas production channel in underground coal gasification production wellhead

In underground coal gasification, crude gas carrying coal ash and cinder has a serious significant erosion effect on the gas extraction area of a wellhead device. To study the erosion of the wellhead device, based on the gas-solid two-phase flow theory, this study uses the discrete phase model to describe the kinematics and trajectories of discrete solid particles and uses the Reynolds-averaged Navier-Stokes equation to calculate the fluid dynamics of the continuous phase. This study determines the main erosion position and the maximum erosion angle range of the wellhead device through numerical analysis, as well as the influence of the changes in solid particle size, particle mass flow rate, and crude gas flow rate on the erosion rate, and predicts the service lifetime of the small four-way and side valve I. The gas-solid erosion experiment verified the maximum erosion angle of the wellhead device. The experimental results were consistent with the numerical analysis results. This study also proposes an optimization method of surfacing to reduce the erosion of gas-solid two-phase flow on wellhead devices. The results show that the inner walls of the small four-way and side valve I are the most eroded. Factors such as particle size, particle mass flow rate, and crude gas flow rate have a greater impact on the erosion rate of the device, and the particle size has the greatest impact. Surfacing the severely eroded area of the wellhead device can effectively reduce the erosion and wear of the wellhead device caused by the gas-solid two-phase flow. This study provides guidance for the reasonable prediction and effective protection of severe erosion areas of wellhead devices.

Numerical simulation of particle erosion in the internal flow field of solid rocket motor nozzle using Rocstar

Solid composite propellants often contain metal particles, such as aluminum particles, and the internal flow field in a solid rocket motor is a typical gas–solid two-phase flow field. In this study, to address the problem of the erosion of particles on the wall during the working process of an engine, a particle erosion model was established based on the interaction mechanism between the particles and the wall. From the perspective of particle dynamics, the interaction mechanism between the moving particles and the wall was analyzed. The force of the particles on the wall surface was obtained, and a formula for solving the particle erosion rate was deduced by using the strength theory and the energy conservation principle. It was combined with Hertz’s contact theory to analyze the factors influencing the erosion rate. In this paper, the particle erosion experiments revealed not only the relationship between erosion rate and erosion angle but also the correlativity between erosion rate and particle concentration. In addition, the experimental results are consistent with the deduced results, which proves the reliability of the model established in this paper. The multiphysics simulation program Rocstar, developed by the Center for Simulation of Advanced Rockets at the University of Illinois, was used to perform a numerical simulation of the two-phase flow in the Jet Propulsion Laboratory nozzle. The results agreed well with the literature and the experimental data. The feasibility and accuracy of the calculation of the gas-phase and two-phase flow fields of the solid rocket motor nozzle were confirmed, laying the foundation for the numerical simulation of the entire process of the full flow field of the engine.

Influence of axial clearance on solid particle erosion and efficiency of governing stage in ultra-supercritical steam turbine based on rebound effect

• Solid particle erosion (SPE) are analyzed combined with rebound effect. • Erosion degree caused by rebound is less than that caused by particle first impact. • When the axial clearance increases, erosion area extends to the front of rotor blade, but erosion degree decreases. • Influence trend of axial clearance on SPE and stage efficiency is different. Based on the steam-solid two-phase flow model combined with rebound effect, the influence of axial clearance on the solid particle erosion (SPE) characteristics and efficiency in ultra-supercritical steam turbine governing stage was analyzed. The results show that the erosion damage degree caused by rebound is less than that caused by the particle first impact. With the increase of axial clearance, the number of particles rebounding back to the trailing edge of the suction surface(SS) in nozzle decreases. When the axial clearance increases, the large size particle impact velocity and impact angle move towards the leading edge of rotor blade, and the erosion area extends to the middle and front of the pressure surface (PS), resulting in the increase of erosion area. However, the particle impact angle deviates from the serious erosion angle, and the erosion degree decreases. The axial clearance has different influence trends on SPE and stage efficiency. With the increase of axial clearance, the erosion rate density decreases continuously, about 59.2%, but the stage efficiency increases first and then decreases. So the influence of SPE and stage efficiency should be comprehensively considered for the selection of axial clearance.

Solid Particle Erosion Behavior of La2Ce2O7/YSZ Double-Ceramic-Layer and Traditional YSZ Thermal Barrier Coatings at High Temperature

Thermal barrier coatings (TBC) used for turbine blades are indispensable for the most advanced aero-engines due to their excellent thermal insulation performance. Solid particle erosion (SPE) at high temperatures is one of the most critical factors in TBC failure. The high-temperature SPE failure behavior of TBC on circular sheets and turbine blades was investigated in this paper at erosion angles 60° and 90°. The high-temperature thermal shock behavior of TBC was also studied as the control group. The SPE failure mechanism of TBC is attributed to the spallation and thickness decrease of TBC. The formation of thermally grown oxide is the main reason for the TBC spallation, while the thickness decrease of TBC is due to the impaction of solid particles by near-surface cracking. The erosion angle is critical to the failure behavior of TBC, and TBC is more susceptible to SPE at an erosion angle of 60° than that at 90° because of the additional shear stress. Furthermore, a La2Ce2O7/YSZ double-ceramic-layer TBC was designed and deposited on turbine blades. The experimental results indicate that this type of double-layer TBC has more excellent performance under SPE than traditional YSZ TBC.