Blade Surface Research Articles

Mangrove plants are promising bioindicator of coastal atmospheric microplastics pollution

Plastics are commonly used by society and their break down into millimeter-sized bits known as microplastics (MPs). Due to the possibility of exposure, reports of them in atmospheric deposition, indoor, and outdoor air have sparked worry for public health. In tropical and subtropical regions all throughout the world, mangroves constitute a distinctive and significant type of coastal wetlands. Mangrove plants are considered to have the effect of accumulating sediment MPs, but the sedimentation of atmospheric MPs has not been reported. In this study, we illustrated the characteristics, abundance and spatial distribution of MPs in different species of mangrove leaves along the Seagull Island in Guangzhou. MPs samples from leaves in five species showed various shapes, colors, compositions, sizes and abundance. Acanthus ilicifolius had an average fallout rate of 1223 items/m2/day which has the highest abundance of MPs in all samples. Four shapes of MPs were found in all leaves surfaces including fiber, fragment, pellet, and film, with fiber is the most. The dominant types of MPs in all leaves were cellulose and rayon. Most of the total MPs size were smaller than 2 mm. Clearly, the microstructures of each species leaf surfaces had an impact on its ability to retain MPs. The plants rough blade surfaces and big folds or gullies caused more particles to accumulate and had a higher MPs retention capacity. Overall, our study contributes to a better knowledge of the condition of MPs pollution in atmosphere and the connection between leaves structure and the retention of MPs, which indicates that mangrove plants are promising bioindicator of coastal atmospheric MPs pollution.

Simulation of particle deposition on high temperature turbine film cooling blade surface with dynamic mesh morphing

Particles carried by gas and impurities in the operation environment can deposit on turbine blades. The deposition of particles on high temperature turbine blade can seriously damage aerodynamic efficiency and cooling characteristic. Numerical simulations are utilized to investigate particle deposition and the influence of deposition on cooling performance of high temperature turbine blade. The Euler Lagrangian method is chosen to track particles. Firstly, a deposition model is developed to estimate particle deposition by User Defined Function (UDF) of Fluent. On the basis of it, dynamic mesh morphing is used to simulate the blade surface changes caused by deposition. It is mainly explored the differences in the number, thickness, and distribution of particle deposition with different particle sizes and blowing ratios. The effect of particle deposition on film cooling effectiveness is also taken into account. The result shows that particle deposition is more likely to occur at the leading edge of the blade and near the trailing edge of pressure side. Deposition on the pressure side near the leading edge can make a positive effect on cooling effectiveness. For different particle diameters, the deposition number of 10 μm particles is highest, the maximum deposit thickness of 20 μm even exceeds 2 mm. For different blowing ratios, the influence of particle deposition is mainly reflected in the middle of the pressure side. The cooling effectiveness loss can reach 30%.

A de-icing experimental investigation of blade airfoil for wind turbines based on external hot air method

Wind turbines operating in cold and wet climates are prone to icing on the surface of their blades. It is necessary to develop effective de-icing methods for wind turbine blades. The commonly used blade de-icing method is heating, which includes the blade internal hot air method and the surface heating method. Recently, the use of external heat sources for blade de-icing has also received attention, such as the use of steam, infrared, and hot air, etc. In this research, the external hot air de-icing method for wind turbine blade was studied by experiments. A de-icing experimental system based on external hot air method was designed and established. The de-icing test was carried out on a blade segment with NACA0018 airfoil. The initial ice shape of blade airfoil was obtained by using an icing wind tunnel. The de-icing experiments were set up with four hot air temperatures and four hot air velocities. The deicing process was recorded by a high-speed camera, and the temperature changes on the blade surface are measured by an infrared thermal instrument. Furthermore, the de-icing time, de-icing area, de-icing rate and de-icing energy efficiency under different conditions were calculated and analyzed. According to the results, the external hot air method can effectively perform blade de-icing. The temperature and speed of the hot air have a significant impact on the de-icing process. Under the condition of this test, the maximum de-icing energy efficiency reached as 6.33 % at hot air temperature of 35 °C and velocity of 9 m/s. This study can provide a reference for solving the wind turbine blade icing problem by using external hot air de-icing method.

Blade aerodynamic force and tip region vortex spatial-temporal evolution study of a compressor cascade

This paper utilized a numerical simulation method to get the vortex structure and aerodynamic force in a low-speed compressor cascade at 5-deg incidence with a hybrid unsteady Reynolds averaged Navier-Stokes/large eddy simulation (URANS/LES) turbulence model. The aerodynamic force, tip leakage vortex (TLV), and the mainstream flow interaction, especially in the blade tip region, are well analyzed. The instant flow pattern showed that the tip secondary leakage vortex and trailing edge backflow radial vortex occur by turning in the tip region. The spanwise flow pattern analysis exhibited that the dilation item dominates the tip region flow instability. The integral aerodynamic force at different spans showed that the tip region aerodynamic forces are far greater than that of mid-span and root-span. The correlation analysis between the aerodynamic force peak and the vortex structure showed that the float in and out of the trailing edge radial vortex closely relates to the aerodynamic force peak value change. The proper orthogonal decomposition (POD) mode results showed that the static pressure on the blade surface refers closely to the leakage vortex structures. The POD time coefficient curves and the aerodynamic force wave results showed that the tip secondary leakage vortex and the radial vortex at the trailing edge in the tip region dominate the aerodynamic force in the tip region. This research found a correlation between the POD mode time coefficient and blade aerodynamic force.

Experimental studies of screw drill with frozen soil interaction

Introduction. The process of formation of wells in frozen soils is one of the complex processes of excavation. A drilling tool of a new geometric shape forms a well by brittle destruction of the rock. The purpose of the conducted experimental studies was to determine the effect on the energy intensity of the drilling process and on the well diameter coefficient of the angle of rotation of the radius of the screw blade, at which its increment occurs on the destructive part and the angle of inclination of the forming upper surface of the screw blade to the axis of rotation.Materials and methods. The article describes a methodology for conducting laboratory experiments to study the interaction of a drilling tool of a new geometric shape with frozen soils. The ranges of values of the studied factors are determined. The matrix of the complete factorial experiment is constructed.Results. As a result of laboratory experiments, the influence of the geometric parameters of the drilling tool on the energy intensity of the drilling process and on the well diameter coefficient was determined. The dependencies of the torque and the well diameter coefficient on the angle of rotation of the radius of the helical blade, at which its increment occurs on the destructive part, the angle of inclination of the forming upper surface of the helical blade to the axis of rotation and the angle of elevation of the middle helical line of the helical blade are established.Discussions and conclusion. It is established that the drilling tool carries out the formation of a well due to the brittle destruction of the well, which makes it possible to achieve more efficient drilling. And also the dependences of the rational values of the investigated geometric parameters of the drilling tool of a new geometric shape are determined.

Study on the Influence of Tip Clearance on Cavitation Performance and Entropy Production of an Axial Flow Pump

The clearance existing between the impeller rim and the adjacent shroud within the pump configuration establishes conducive circumstances for the initiation of cavitation. The bubbles generated by cavitation will flow forward with the water, blocking the channel, and result in the degradation of the pump performance. When the cavitation is severe, vibration and noise will be generated. The impact formed by the collapse of the bubbles will seriously erode the blades and form pits on the blade surfaces. Drawing upon the outcomes derived from numerical simulations, this paper investigates the relationship between tip clearance and cavitation in an axial flow pump, with a specific focus on energy dissipation characteristics. The principal findings indicate that the dimensions of the tip clearance predominantly influence the spatial distribution of the tip leakage vortex (TLV) cavitation. The entropy production rate distribution at the tip correlates with both the cavitation level of the pump and the extent of the tip clearance. The shedding phenomenon of the TLV becomes more evident when analyzing the distribution of entropy production rates. During cavitation, an increased tip clearance is associated with a reduction in the dissipation of viscous entropy production within the impeller domain, and the entropy production resulting from turbulent dissipation significantly surpasses that arising from viscous dissipation.

Adaptive positioning technology of film cooling holes in hollow turbine blades

Film cooling technology is widely used in hollow turbine blades of aero-engine with a high thrust-to-weight ratio. The positioning accuracy of film cooling holes directly affects the uniformity and adhesion of the cooling film on blade surfaces. Two main factors affect the positioning accuracy of film cooling holes, i.e., the profile deformation of the blades during manufacturing and the blade clamping error in computer numerical control equipment. The positioning technology of film cooling holes has rarely been investigated. In this study, an adaptive positioning method is proposed to provide a reference for innovative research in this field. First, this study proposes a method for measuring and compensating blade clamping error based on the point cloud data of the entire blade surface obtained with optical scanning equipment by combining the rigid-body transformation theory and three-dimensional point cloud matching method. Second, owing to the complex overall deformation of the blade surface, this study innovatively focuses on the deformation of each slice from a local perspective. Furthermore, the deformation of each slice is decomposed into bending, torsion, and uneven shrinkage. The bending and torsion deformations are compensated based on the two-dimensional rigid-body matching method, while the remaining uneven shrinkage deformation is compensated by the position mapping method. The effectiveness and accuracy of the proposed method are qualitatively and quantitatively verified by the adaptive positioning results of film cooling holes in actual and test blades. The maximum spatial position and angle deviations are 0.0561 mm and 0.6946°, respectively.

Controlling the flow loss of a supersonic compressor rotor using the blade slotting method

The flow loss in the blade passage of a supersonic compressor rotor mainly comes from the boundary layers on the blade surface and end wall, the shock wave, the shock wave/boundary layer interaction, and tip leakage flow; the instability is mainly caused by the shock wave near the rotor blade tip exiting the blade passage. This paper adopts an internal slot in the blade, with the inlet of the slot located at the leading edge of the blade and the outlet located on the suction surface of the blade, by using the momentum of the incoming flow to form a high-velocity jet to control the flow loss and improve the stall margin of the supersonic rotor. The mechanism of reducing flow loss by a slotting jet was studied, and a genetic algorithm optimization platform was further used for the coupled optimization design of the slot and blade. The numerical calculation results showed that the slotting jet can effectively suppress the development of the boundary layer on the suction surface while reducing the intensity of the shock wave, thereby reducing the loss of the boundary layer and shock wave, significantly improving the peak efficiency of the rotor, and increasing the mass flow rate at the peak efficiency point. The slotting jet can cause the shock wave in the passage to move downstream, thereby improving the stall margin of the rotor. Due to the strong shock wave in the blade passage near the blade tip, the slot outlet should be near and upstream of the shock wave; the shock wave in the middle and root regions of the blade is weaker, and the slot outlet should be located downstream of the shock wave.

Numerical investigation of wind turbine wake characteristics using a coupled CFD-CSD method considering blade and tower flexibility

With the increase in wind turbine sizes, careful investigation into wind turbine wake effect is crucial for operational safety. This study proposes a two-way fluid-structure interaction (FSI) model combining large eddy simulation (LES) and computational structural dynamics (CSD) to investigate wind turbine wake characteristics. Examining the effect of blade and tower flexibility and inflow conditions, the study reveals negligible influence of blade and tower flexibility on mean velocity deficit under both inflow conditions. However, they significantly impact turbulence intensity under uniform inflow condition. The tower motion produces a maximum increase of approximately 45% while the blade flap-wise motion has the second-largest impact, increasing the maximum turbulence intensity by approximately 33% when compared with the fully rigid case. Additionally, the study quantitatively examines wake vortex inclination based on the inclination angle of the second-circle wake vortex structure. Finally, the study concludes that the streamline near the blade tip follows the blade surface, while the flow separation occurs near the blade root, generating two vortices on the suction side. As the tower motion is considered, the larger vortex exhibits alternate vortex shedding while the smaller vortex remains stable in both uniform and turbulent winds.

Application of CVD Coatings on the Inner Surfaces of Cooled GTE Blades

Application of CVD Coatings on the Inner Surfaces of Cooled GTE Blades

Computational Approach to Geometric Modeling of Plow Bodies

In this article, a detailed analysis of modern research and publications on the selected subject was carried out related to the computer-variant geometric modeling of the working surfaces of the plow blades. Based on this, a new method of proper design was proposed. The performed scientific investigations aimed to create a flexible, productive, and universal approach for the automated shaping of tillage tools. The accentuated effectiveness of geometric modeling was achieved using a developed special mathematical apparatus adapted for use in the environment of current computer information systems of an engineering profile. The implementation was based on such parametric lines as heterogeneous rational B-splines, which are acceptable in automated design systems. The specified geometric models were characterized by the coverage of a sufficiently large range of plow heads. The indicated means of forming could conveniently adapt to the changing conditions of designing tillage tools suggested by theoretical calculations and practical experiments. The given facts contributed to the multifaceted clarification of the specified information. They also ensured the appropriate integration and the possibility of determining the most rational options among the studied varieties of plow dumps. Simultaneously, the most common group of dumps with cylindrical and other plow working surfaces was considered. The significant role of geometric models for qualitative coordination and the effective combination of many other models (e.g., strength, manufacturing technology, and operation conditions) was emphasized. This was aimed at comprehensive optimization throughout their life cycle, in this case of plows. The proper solution to the presented problems contributed to a successful solution to the actual scientific and applied problem of improving the quality of machinery.

Enhancing the performance of Savonius rotor using tiered-height zigzag patterns in concave surface

A technique to reduce CO2 emissions from the use of fossil fuels is to use clean energy. One of them is wind energy, which is generated by a wind turbine. Savonius, a type of vertical axis wind turbine, is a small-scale energy conversion device suitable for low wind speeds, such as those characteristic of Indonesian wind speed. The objective of the current study was to analyze the impact of implementing a tiered-height zigzag pattern on the concave surface of the Savonius blade. The zigzag angle operates to direct the wind toward the reverse blade, consequently augmenting the pressure on the reverse blade. In addition, the tiered-height zigzag pattern in the concave surface increases the area of the turbine that is in contact with the wind, which in turn generates more energy. This study used an open-type wind tunnel to conduct experiments as the primary technique of investigation. Its performance was assessed in terms of power and torque coefficients. Additionally, experiments were conducted with other standard semi-circular blades to get a direct comparison. According to the findings of the experiments, incorporating a tiered-height zigzag pattern into a concave surface may produce a power coefficient (Cp) that is 16 % higher than that of a semi-circular. The highest Cp was 0.286 at a TSR of 0.55 and U = 6 m/s. In this case, the Savonius wind turbine's ability may be elevated by including a tiered-height zigzag pattern in the Savonius concave surface.

Influence of tip clearance on internal energy loss characteristics of axial flow pumps under different operating conditions

Axial flow pumps possess a unique structure where there must be clearances between the impeller and the piping wall, usually not exceeding 0.1% of the impeller diameter. Despite the small size of the clearance, the internal micro-vortex structures have a non-negligible impact on the main flow field of the impeller. Under the action of the pressure difference between the suction and pressure surfaces of blades, some fluids form high-energy jets in the tip clearance area, known as tip leakage vortices (TLVs). TLV interacts with the flow of the main flow field, exerting a significant impact on the internal flow state, energy loss, and hydraulic performance of the pump. To identify the influence of TLVs on the internal flow field and energy loss of axial flow pumps, this work uses a modified partially averaged Navier–Stokes (PANS) model to perform full flow field numerical calculations for a certain axial flow pump and conducts a comparative analysis of the internal flow field energy dissipation, unsteady vortex structures, energy loss, and other characteristics under three different tip clearances: 0.2 mm (0.05%D), 0.6 mm (0.15%D), and 1.0 mm (0.25%D) based on the energy transport theory. The results indicate that at optimal operating conditions, the internal energy distribution of the fluid in each flow passage is uniform, and the energy loss is primarily caused by axial backflow in the tip area; under critical rotating stall conditions, clearance size affects the distribution state of enstrophy in the guide vane flow passage, leading to average enstrophy being highest at the rim area and the most uneven distribution of enstrophy, inducing larger energy loss in the impeller; during deep stall conditions, the unevenness of internal energy distribution is stronger than that under critical stall conditions, but the overall energy loss within the impeller flow area is lower than that under critical stall conditions, while energy unevenness is mitigated as the tip clearance size increases.

Research on Intelligent Detection System for Visualization of Saw Blade Surface Defects Based on Deep Learning

Research on Intelligent Detection System for Visualization of Saw Blade Surface Defects Based on Deep Learning

Experimental study and modeling of water film thickness in aero-engine under air–water mist flow

The water film not only plays an important role in the mass, momentum, and energy transfer between the air–water-surface but also determines the on-wing washing effect of the aero-engine. In view of this, air–water mist flow visualization experiments have been conducted at different gas velocities and water-to-air ratios in a compressor cascade, and the microscopic water film images have been analyzed to extract the transient water film thickness data by the Matlab code. It was found that the transient water film thickness fluctuation has no obvious association with the gas velocity, and the water film fluctuation is more affected by the water-to-air ratio. As the water-to-air ratio increases, the fluctuation magnitude of the water film thickness increases. The average water film thickness has been studied in relation to gas velocity and water flow rate, i.e., the average thickness of water film decreases with increasing gas velocity and increase with the increasing water flow rate. On the basis of the water film flow equation and taking the droplet collection efficiency into account, i.e., from the perspective of the physical mechanism of water film formed, a new model for predicting the water film thickness of a compressor blade surface under the air–water mist flow condition was proposed and validated. This model predicted, with a root mean square error and the mean absolute percentage error of 11.6% and 9.15%, respectively, under the present experimental flow conditions.

A cooled turbine blade design and optimization method considering the cooling structure influence

This study introduces a multidisciplinary design methodology tailored for enhancing the performance of cooled turbine blades by amalgamating thermal and aerodynamic calculation modules. The approach is unique in terms of its integration of a multi-objective optimization platform, aimed at refining aerodynamic performance and gauging the heat transfer capabilities during the preliminary aerodynamic design phase. To accomplish this objective, a one-dimensional pipe-network calculation tool was incorporated into the thermal module to quickly evaluate the heat transfer performance of the blades under different conditions. This tool also provides more realistic film hole inlet boundary conditions essential for three-dimensional aerodynamic calculations. Implementing this platform in optimizing a high-pressure turbine blade revealed a Pareto-optimal front, comprising −η1 and η2 (representing optimization objectives for aerodynamic and heat transfer performance, respectively), showcasing a constrained relationship. Upon scrutinizing three optimization cases against the prototype, optimization case 1 demonstrates the most significant enhancements in aerodynamic performance, showing a 0.2015% improvement in aerodynamic efficiency relative to the prototype. Conversely, optimization case 3 displays a comparatively modest augmentation in aerodynamic performance but excels notably in heat transfer performance, showcasing a 7.61% reduction in the maximum temperature of the blade surface compared to the prototype. Through adept optimization strategies and meticulous variable selection, we maintained a relatively stable mainstream mass flow across the optimization cases (less than 0.05% variation). These findings underscore the efficacy of our multidisciplinary design approach for cooled turbine blades, promising efficiency improvements in current design practices and potential reductions in project duration.

Impact of microgeometric parameters on the sliding cutting behavior of macaroni products

The primary objectives of the food industry sectors in the Republic of Uzbekistan are to intensify and optimize technological processes, adopt new progressive equipment for efficient processing modes, reduce energy costs and raw material losses, and improve product quality. Accordingly, this article presents a solution to one of the problems and provides an analysis of the cutting ability of the tool based on the investigated set of blade microgeometry parameters. The research aims to determine the numerical values of the microgeometry parameters for lamellar knife blades, obtained through various formation methods, and to identify the nature of their changes during operation. Additionally, the study explores the possibility of achieving such blade microgeometry parameters during sharpening, which were obtained through the optimization of the cutting ability objective function. The system described in the article has been implemented using the method of microscopic examination of lamellar knives, which allows for the photography of the blade surface and facets, contributing to the visual control of the cutting-edge condition immediately after its formation and during operation.

A Numerical Study on the Energy Dissipation Mechanisms of a Two-Stage Vertical Pump as Turbine Using Entropy Generation Theory

Utilizing a two-stage vertical pump as turbine (TVPAT) is an economically method for constructing small-scale pumping and storage hydropower stations at high head-low discharge sites, such as underground coal mines. The energy dissipation mechanisms in flow passages are theoretically important for performance prediction and geometric parameter optimization. In this paper, the energy dissipation within the TVPAT has been studied using entropy generation theory, which can be applied to visual, locate and quantify energy dissipation. The numerical solution of entropy dissipation components was extracted on turbine modes in different flow rates using the steady-state single-phase SST k-ω turbulence model. The numerical results show that the energy dissipation in TVPAT mainly comes from turbulent fluctuation (43.6%-72.1%) and blade surface friction (27.8%-58.2%). The runners are the main source of turbulent entropy (SD′ ) generation (47.2%-83.3%). The contribution of the return channel and spiral case to the generation under overload conditions is significant, accounting for 33.6% and 14.3 at 1.3QBEP, respectively. Flow field analysis reveals that high generation within a runner are located in the striking flow region of the leading edge, the flow squeezing region in the blade channel, and the wake region of tailing edge. The mismatch between the placement angle of the blades or guide vanes and the liquid flow angle is an important incentive for SD′ generation. Moreover, hydraulic energy is consumed through the interaction between mainstream and local inferior flows such as separation and vortices, as well as the striking and friction between local fluid and wall surfaces.

Numerical study on cooling performance and thermal stress characteristic of an f-class gas turbine stator blade

In this study, a coupled numerical computation approach integrating aerothermal and thermomechanical effects was employed to investigate the cooling efficiency and thermal stress characteristics of gas turbine stator blades. A comprehensive analysis was conducted considering varying turbulence intensities in the coolant flow (spanning from 0.05 to 0.15) and different coolant media configurations, including pure air, dual-medium mixture of air and steam, and pure steam. The distributional traits of cooling efficiency and thermal stress on the stator blade surface under these conditions were meticulously examined. Furthermore, quantitative assessments were performed to determine the extentto which coolant turbulence intensity and coolant type affect the average cooling efficiency and maximum equivalent thermal stress of turbine stator blades, thereby revealing the influence laws. The results reveal that the minimum cooling efficiency on the stator blade surface predominantly occurs at the position of channel 4 on the pressure surface, while the highest cooling efficiency is generally found near the leading edge of the suction surface. Regions of elevated thermal stress were consistently concentrated around the stator blade tip and root areas. When the coolant turbulence intensity increased from 0.05 to 0.15, the average cooling efficiency on the stator blade surface improved by 2.06%, accompanied by a reduction of 1.12% in the maximum thermal stress. In comparison to pure air cooling, dual-medium (air and steam) cooling and pure steam cooling lead to respective enhancements in the average cooling efficiency of approximately 3.3% and 13.2%, with corresponding decreases in the maximum thermal stress of 2.18% and 10.2%.

ASSESSMENT OF THE CURRENT AGROBIOLOGICAL STATE OF THE PROTECTED FOREST STRIPS OF THE RIGHT BANK FOREST STEPPE

ASSESSMENT OF THE CURRENT AGROBIOLOGICAL STATE OF THE PROTECTED FOREST STRIPS OF THE RIGHT BANK FOREST STEPPE