The accumulation of defects on wind turbine blade surfaces can lead to irreversible damage,impacting the aero-dynamic performance of the blades.To address the challenge of detecting and quantifying surface defects on ...The accumulation of defects on wind turbine blade surfaces can lead to irreversible damage,impacting the aero-dynamic performance of the blades.To address the challenge of detecting and quantifying surface defects on wind turbine blades,a blade surface defect detection and quantification method based on an improved Deeplabv3+deep learning model is proposed.Firstly,an improved method for wind turbine blade surface defect detection,utilizing Mobilenetv2 as the backbone feature extraction network,is proposed based on an original Deeplabv3+deep learning model to address the issue of limited robustness.Secondly,through integrating the concept of pre-trained weights from transfer learning and implementing a freeze training strategy,significant improvements have been made to enhance both the training speed and model training accuracy of this deep learning model.Finally,based on segmented blade surface defect images,a method for quantifying blade defects is proposed.This method combines image stitching algorithms to achieve overall quantification and risk assessment of the entire blade.Test results show that the improved Deeplabv3+deep learning model reduces training time by approximately 43.03%compared to the original model,while achieving mAP and MIoU values of 96.87%and 96.93%,respectively.Moreover,it demonstrates robustness in detecting different surface defects on blades across different back-grounds.The application of a blade surface defect quantification method enables the precise quantification of dif-ferent defects and facilitates the assessment of risk levels associated with defect measurements across the entire blade.This method enables non-contact,long-distance,high-precision detection and quantification of surface defects on the blades,providing a reference for assessing surface defects on wind turbine blades.展开更多
An investigation made on the rotor blade tip vortex through use of a Three Dimensional Laser Doppler Velocimetry(3D LDV) is described. The experiment is conducted with a 2 m in diameter model helicopter rotor. By a ...An investigation made on the rotor blade tip vortex through use of a Three Dimensional Laser Doppler Velocimetry(3D LDV) is described. The experiment is conducted with a 2 m in diameter model helicopter rotor. By a series of measurements near blade tip, the velocity field near blade tip is documented, and through which, the tip vortex rollup and development are presented. The radial distribution of instantaneous velocities at various levels above and under the rotor disc is also measured in this investigation. Using this distribution, the influence of the tip vortex from the preceding blade on the follow up blade is discussed.展开更多
The double blade pump is widely used in sewage treatment industry,however,the research on the internal flow characteristics of the double blade pump with particle image velocimetry（PIV） technology is very little at ...The double blade pump is widely used in sewage treatment industry,however,the research on the internal flow characteristics of the double blade pump with particle image velocimetry（PIV） technology is very little at present.To reveal inner flow characteristics in double blade pump impeller under off-design and design conditions,inner flows in a double blade pump impeller,whose specific speed is 111,are measured under the five off-design conditions and design condition by using 3D PIV test technology.In order to ensure the accuracy of the 3D PIV test,the external trigger synchronization system which makes use of fiber optic and equivalent calibration method are applied.The 3D PIV relative velocity synthesis procedure is compiled by using Visual C＋＋ 2005.Then absolute velocity distribution and relative velocity distribution in the double blade pump impeller are obtained.Test results show that vortex exists in each condition,but the location,size and velocity of vortex core are different.Average absolute velocity value of impeller outlet increases at first,then decreases,and then increases again with increase of flow rate.Again average relative velocity values under 0.4,0.8,and 1.2 design condition are higher than that under 1.0 design condition,while under 0.6 and 1.4 design condition it is lower.Under low flow rate conditions,radial vectors of absolute velocities at impeller outlet and blade inlet near the pump shaft decrease with increase of flow rate,while that of relative velocities at the suction side near the pump shaft decreases.Radial vectors of absolute velocities and relative velocities change slightly under the two large flow rate conditions.The research results can be applied to instruct the hydraulic optimization design of double blade pumps.展开更多
Diamond tools with orderly arrangements of diamond grits have drawn considerable attention in the machining field owing to their outstanding advantages of high sharpness and long service life.This diamond super tool,a...Diamond tools with orderly arrangements of diamond grits have drawn considerable attention in the machining field owing to their outstanding advantages of high sharpness and long service life.This diamond super tool,as well as the manufacturing equipment,has been unavailable to Chinese enterprises for a long time due to patents.In this paper,a diamond blade segment with a 3D lattice of diamond grits was additively manufactured using a new type of cold pressing equipment(AME100).The equipment,designed with a rotary working platform and 16 molding stations,can be used to additively manufacture segments with diamond grits arranged in an orderly fashion,layer by layer;under this additive manufacturing process,at least 216000 pcs of diamond green segments with five orderly arranged grit layers can be produced per month.The microstructure of the segment was observed via SEM and the diamond blade fabricated using these segments was compared to other commercial cutting tools.The experimental results showed that the 3D lattice of diamond grits was formed in the green segment.The filling rate of diamond grits in the lattice could be guaranteed to be above 95%;this is much higher than the 90%filling rate of the automatic array system(ARIX).When used to cut stone,the cutting amount of the blade with segments made by AME100 is two times that of ordinary tools,with the same diamond concentration.When used to dry cut reinforced concrete,its cutting speed is 10%faster than that of ARIX.Under wet cutting conditions,its service life is twice that of ARIX.By applying the machine vision online inspection system and a special needle jig with a negative pressure system,this study developed a piece of additive manufacturing equipment for efficiently fabricating blade segments with a 3D lattice of diamond grits.展开更多
The 3D inverse design method, which methodology is far superior to the conventional design method that based on geometrical description, is gradually applied in pump blade design. However, no complete description abou...The 3D inverse design method, which methodology is far superior to the conventional design method that based on geometrical description, is gradually applied in pump blade design. However, no complete description about the method is outlined. Also, there are no general rules available to set the two important input parameters, blade loading distribution and stacking condition. In this sense, the basic theory and the mechanism why the design method can suppress the formation of secondary flow are summarized. And also, several typical pump design cases with different specific speeds ranging from centrifugal pump to axial pump are surveyed. The results indicates that, for centrifugal pump and mixed pump or turbine, the ratio of blade loading on the hub to that on the shroud is more than unit in the fore part of the blade, whereas in the aft part, the ratio is decreased to satisfy the same wrap angle for hub and shroud. And the choice of blade loading type depends on the balancing of efficiency and cavitation. If the cavitation is more weighted, the better choice is aft-loaded, otherwise, the fore-loaded or mid-loaded is preferable to improve the efficiency. The stacking condition, which is an auxiliary to suppress the secondary flow, can have great effect on the jet-wake outflow and the operation range for pump. Ultimately, how to link the design method to modem optimization techniques is illustrated. With the know-how design methodology and the know-how systematic optimization approach, the application of optimization design is promising for engineering. This paper summarizes the 3D inverse design method systematically.展开更多
A three-dimensional model of the Logone Birni Basin (LBB) is presented by combining gravity and magnetic data and constrained by broad seismic profiles. The 3-D model has revealed the distribution of the stratigraphic...A three-dimensional model of the Logone Birni Basin (LBB) is presented by combining gravity and magnetic data and constrained by broad seismic profiles. The 3-D model has revealed the distribution of the stratigraphic formations as well as the top basement variation. Detailed structure of different stratigraphic sequences is presented for the first time for this basin and some of the sequences correlate with established sequences of the neighboring basins. The sediments pill consists of six sedimentary units dating from the Neocomian to the Quartenary. The Makary subbasin or Northern Logone Birni Basin (NLBB) is the deepest part of the basin and may hold good prospect for hydrocarbon generation and accumulation. However, the limited presence of faults and intrusive bodies decreases the possibility of thermal degeneration, contrary to the Central Logone Birni Basin (CLBB) where conditions seem to be fulfilled for possible hydrocarbon generation and maturity. The complexity of the structural pattern of the model is further enhanced by the presences of volcanic bodies, some of which lay directly on basement or interbedded with the sediments layers mainly in the CLBB.展开更多
The blade precision forging process is a forming process with high temperature and large plastic deformation. Interaction of deformation and heat conduction leads to large uneven distribution of temperature. The uneve...The blade precision forging process is a forming process with high temperature and large plastic deformation. Interaction of deformation and heat conduction leads to large uneven distribution of temperature. The unevenness of temperature distribution has a great effect on mechanical properties and the microstracture of materials. So it is necessary to consider the influence of temperature on the precision forging process of blades. Taking a blade with a tenon into consideration, a 3D mechanical model in precision forging is built up. The distribution laws of temperature field and the influence of the temperature on the equivalem stress in the process are obtained by using 3-D coupled thermo-mechanical FEM code developed by the authors Theresuits obtained illustrate that the influence of the temperature field on the blade forging process is considerable. The achievements of predicting microstructure and mechanical properties for forged blades is significant.展开更多
A systematic method was developed for ice-class propeller modeling,performance estimation,strength and integrity evaluation and optimization.To estimate the impact of sea ice on the propeller structure,URI3 rules,esta...A systematic method was developed for ice-class propeller modeling,performance estimation,strength and integrity evaluation and optimization.To estimate the impact of sea ice on the propeller structure,URI3 rules,established by the International Association of Classification Societies in 2007,were applied for ice loading calculations.An R-class propeller(a type of ice-class propeller)was utilized for subsequent investigations.The propeller modeling was simplified based on a conventional method,which expedited the model building process.The propeller performance was simulated using the computational fluid dynamics(CFD)method.The simulation results were validated by comparison with experimental data.Furthermore,the hydrodynamic pressure was transferred into a finite element analysis(FEA)module for strength assessment of ice-class propellers.According to URI3 rules,the ice loading was estimated based on different polar classes and working cases.Then,the FEA method was utilized to evaluate the propeller strength.The validation showed that the simulation results accorded with recent research results.Finally,an improved optimization method was developed to save the propeller constituent materials.The optimized propeller example had a minimum safety factor of 1.55,satisfying the safety factor requirement of≥1.5,and reduced the design volume to 88.2%of the original.展开更多
基金supported by the National Science Foundation of China(Grant Nos.52068049 and 51908266)the Science Fund for Distinguished Young Scholars of Gansu Province(No.21JR7RA267)Hongliu Outstanding Young Talents Program of Lanzhou University of Technology.
文摘The accumulation of defects on wind turbine blade surfaces can lead to irreversible damage,impacting the aero-dynamic performance of the blades.To address the challenge of detecting and quantifying surface defects on wind turbine blades,a blade surface defect detection and quantification method based on an improved Deeplabv3+deep learning model is proposed.Firstly,an improved method for wind turbine blade surface defect detection,utilizing Mobilenetv2 as the backbone feature extraction network,is proposed based on an original Deeplabv3+deep learning model to address the issue of limited robustness.Secondly,through integrating the concept of pre-trained weights from transfer learning and implementing a freeze training strategy,significant improvements have been made to enhance both the training speed and model training accuracy of this deep learning model.Finally,based on segmented blade surface defect images,a method for quantifying blade defects is proposed.This method combines image stitching algorithms to achieve overall quantification and risk assessment of the entire blade.Test results show that the improved Deeplabv3+deep learning model reduces training time by approximately 43.03%compared to the original model,while achieving mAP and MIoU values of 96.87%and 96.93%,respectively.Moreover,it demonstrates robustness in detecting different surface defects on blades across different back-grounds.The application of a blade surface defect quantification method enables the precise quantification of dif-ferent defects and facilitates the assessment of risk levels associated with defect measurements across the entire blade.This method enables non-contact,long-distance,high-precision detection and quantification of surface defects on the blades,providing a reference for assessing surface defects on wind turbine blades.
文摘An investigation made on the rotor blade tip vortex through use of a Three Dimensional Laser Doppler Velocimetry(3D LDV) is described. The experiment is conducted with a 2 m in diameter model helicopter rotor. By a series of measurements near blade tip, the velocity field near blade tip is documented, and through which, the tip vortex rollup and development are presented. The radial distribution of instantaneous velocities at various levels above and under the rotor disc is also measured in this investigation. Using this distribution, the influence of the tip vortex from the preceding blade on the follow up blade is discussed.
基金supported by National Outstanding Young Scientists Founds of China (Grant No. 50825902)National Key Technology R&D Program of China (Grant No. 2008BAF34B15)+2 种基金National Natural Science Foundation of China (Grant No. 51079062)Jiangsu Provincial 333 High-level Personal Training Project of ChinaJiangsu Provincial Six Talent Peak of China
文摘The double blade pump is widely used in sewage treatment industry,however,the research on the internal flow characteristics of the double blade pump with particle image velocimetry（PIV） technology is very little at present.To reveal inner flow characteristics in double blade pump impeller under off-design and design conditions,inner flows in a double blade pump impeller,whose specific speed is 111,are measured under the five off-design conditions and design condition by using 3D PIV test technology.In order to ensure the accuracy of the 3D PIV test,the external trigger synchronization system which makes use of fiber optic and equivalent calibration method are applied.The 3D PIV relative velocity synthesis procedure is compiled by using Visual C＋＋ 2005.Then absolute velocity distribution and relative velocity distribution in the double blade pump impeller are obtained.Test results show that vortex exists in each condition,but the location,size and velocity of vortex core are different.Average absolute velocity value of impeller outlet increases at first,then decreases,and then increases again with increase of flow rate.Again average relative velocity values under 0.4,0.8,and 1.2 design condition are higher than that under 1.0 design condition,while under 0.6 and 1.4 design condition it is lower.Under low flow rate conditions,radial vectors of absolute velocities at impeller outlet and blade inlet near the pump shaft decrease with increase of flow rate,while that of relative velocities at the suction side near the pump shaft decreases.Radial vectors of absolute velocities and relative velocities change slightly under the two large flow rate conditions.The research results can be applied to instruct the hydraulic optimization design of double blade pumps.
基金Supported by Scientific Research Funds of Guangdong Province of China(Grant No.2017B090922008)the Scientific Project of Chaozhou of China(Grant No.2018ZD10).
文摘Diamond tools with orderly arrangements of diamond grits have drawn considerable attention in the machining field owing to their outstanding advantages of high sharpness and long service life.This diamond super tool,as well as the manufacturing equipment,has been unavailable to Chinese enterprises for a long time due to patents.In this paper,a diamond blade segment with a 3D lattice of diamond grits was additively manufactured using a new type of cold pressing equipment(AME100).The equipment,designed with a rotary working platform and 16 molding stations,can be used to additively manufacture segments with diamond grits arranged in an orderly fashion,layer by layer;under this additive manufacturing process,at least 216000 pcs of diamond green segments with five orderly arranged grit layers can be produced per month.The microstructure of the segment was observed via SEM and the diamond blade fabricated using these segments was compared to other commercial cutting tools.The experimental results showed that the 3D lattice of diamond grits was formed in the green segment.The filling rate of diamond grits in the lattice could be guaranteed to be above 95%;this is much higher than the 90%filling rate of the automatic array system(ARIX).When used to cut stone,the cutting amount of the blade with segments made by AME100 is two times that of ordinary tools,with the same diamond concentration.When used to dry cut reinforced concrete,its cutting speed is 10%faster than that of ARIX.Under wet cutting conditions,its service life is twice that of ARIX.By applying the machine vision online inspection system and a special needle jig with a negative pressure system,this study developed a piece of additive manufacturing equipment for efficiently fabricating blade segments with a 3D lattice of diamond grits.
基金Supported by National Basic Research Program of China(973 Program,Grant No.2009CB724302)
文摘The 3D inverse design method, which methodology is far superior to the conventional design method that based on geometrical description, is gradually applied in pump blade design. However, no complete description about the method is outlined. Also, there are no general rules available to set the two important input parameters, blade loading distribution and stacking condition. In this sense, the basic theory and the mechanism why the design method can suppress the formation of secondary flow are summarized. And also, several typical pump design cases with different specific speeds ranging from centrifugal pump to axial pump are surveyed. The results indicates that, for centrifugal pump and mixed pump or turbine, the ratio of blade loading on the hub to that on the shroud is more than unit in the fore part of the blade, whereas in the aft part, the ratio is decreased to satisfy the same wrap angle for hub and shroud. And the choice of blade loading type depends on the balancing of efficiency and cavitation. If the cavitation is more weighted, the better choice is aft-loaded, otherwise, the fore-loaded or mid-loaded is preferable to improve the efficiency. The stacking condition, which is an auxiliary to suppress the secondary flow, can have great effect on the jet-wake outflow and the operation range for pump. Ultimately, how to link the design method to modem optimization techniques is illustrated. With the know-how design methodology and the know-how systematic optimization approach, the application of optimization design is promising for engineering. This paper summarizes the 3D inverse design method systematically.
文摘A three-dimensional model of the Logone Birni Basin (LBB) is presented by combining gravity and magnetic data and constrained by broad seismic profiles. The 3-D model has revealed the distribution of the stratigraphic formations as well as the top basement variation. Detailed structure of different stratigraphic sequences is presented for the first time for this basin and some of the sequences correlate with established sequences of the neighboring basins. The sediments pill consists of six sedimentary units dating from the Neocomian to the Quartenary. The Makary subbasin or Northern Logone Birni Basin (NLBB) is the deepest part of the basin and may hold good prospect for hydrocarbon generation and accumulation. However, the limited presence of faults and intrusive bodies decreases the possibility of thermal degeneration, contrary to the Central Logone Birni Basin (CLBB) where conditions seem to be fulfilled for possible hydrocarbon generation and maturity. The complexity of the structural pattern of the model is further enhanced by the presences of volcanic bodies, some of which lay directly on basement or interbedded with the sediments layers mainly in the CLBB.
基金supported by the Aeronautical Science Foundation of China(No.02H53061)the National Science Found of China for Distinguished Young Scholar(No.50225518)the Shaan'xi Provincial Natural Science Foundation of China(No.2001CS0401)
文摘The blade precision forging process is a forming process with high temperature and large plastic deformation. Interaction of deformation and heat conduction leads to large uneven distribution of temperature. The unevenness of temperature distribution has a great effect on mechanical properties and the microstracture of materials. So it is necessary to consider the influence of temperature on the precision forging process of blades. Taking a blade with a tenon into consideration, a 3D mechanical model in precision forging is built up. The distribution laws of temperature field and the influence of the temperature on the equivalem stress in the process are obtained by using 3-D coupled thermo-mechanical FEM code developed by the authors Theresuits obtained illustrate that the influence of the temperature field on the blade forging process is considerable. The achievements of predicting microstructure and mechanical properties for forged blades is significant.
基金The author would like to thank University of Tasmania and Newcastle University for their support。
文摘A systematic method was developed for ice-class propeller modeling,performance estimation,strength and integrity evaluation and optimization.To estimate the impact of sea ice on the propeller structure,URI3 rules,established by the International Association of Classification Societies in 2007,were applied for ice loading calculations.An R-class propeller(a type of ice-class propeller)was utilized for subsequent investigations.The propeller modeling was simplified based on a conventional method,which expedited the model building process.The propeller performance was simulated using the computational fluid dynamics(CFD)method.The simulation results were validated by comparison with experimental data.Furthermore,the hydrodynamic pressure was transferred into a finite element analysis(FEA)module for strength assessment of ice-class propellers.According to URI3 rules,the ice loading was estimated based on different polar classes and working cases.Then,the FEA method was utilized to evaluate the propeller strength.The validation showed that the simulation results accorded with recent research results.Finally,an improved optimization method was developed to save the propeller constituent materials.The optimized propeller example had a minimum safety factor of 1.55,satisfying the safety factor requirement of≥1.5,and reduced the design volume to 88.2%of the original.
