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Investigation of vortical flows over oscillating body using fast Lagrangian vortex method

Baoshan ZHU ,

《能源前沿（英文）》 2009年 第3卷 第3期   页码 297-306 doi: 10.1007/s11708-009-0010-4

摘要： A computational method facilitating long-time and high-resolution unsteady vortical flows is developed with the advantages of the discrete vortex methods. Both the velocity and pressure distribution of the flow field are calculated by integral formulations in combination with a fast summation algorithm. The vorticity field is described by Lagrangian representation, which is well suited to the moving boundary. Viscosity diffusion of the vorticity is considered with the core spreading model corrected by an adaptive splitting and merging algorithm. The effectiveness of the present method is examined by comparing the numerical results of unsteady separated flows which pass a cylinder and a thin cambered blade undergoing rotational oscillations with available experimental results. Interesting results about vortex shedding patterns and lock-in characteristics are provided for the thin cambered blade.

关键词： unsteady vortical flows     fast vortex method     vortex shedding     rotational oscillation     thin cambered blade    

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Hysteretic behavior of cambered surface steel tube damper: Theoretical and experimental research

《结构与土木工程前沿（英文）》 2023年 第17卷 第4期   页码 606-624 doi: 10.1007/s11709-023-0925-6

摘要： A novel cambered surface steel tube damper (CSTD) with a cambered surface steel tube and two concave connecting plates is proposed herein. The steel tube is the main energy dissipation component and comprises a weakened segment in the middle, a transition segment, and an embedded segment. It is believed that during an earthquake, the middle weakened segment of the CSTD will be damaged, whereas the reliability of the end connection is ensured. Theoretical and experimental studies are conducted to verify the effectiveness of the proposed CSTD. Formulas for the initial stiffness and yield force of the CSTD are proposed. Subsequently, two CSTD specimens with different steel tube thicknesses are fabricated and tested under cyclic quasi-static loads. The result shows that the CSTD yields a stable hysteretic response and affords excellent energy dissipation. A parametric study is conducted to investigate the effects of the steel tube height, diameter, and thickness on the seismic performance of the CSTD. Compared with equal-stiffness design steel tube dampers, the CSTD exhibits better energy dissipation performance, more stable hysteretic response, and better uniformity in plastic deformation distributions.

关键词： cambered surface steel tube damper     energy dissipation capacity     finite element model     hysteretic performance     parametric study    

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Vibration analysis of blade-disc coupled structure of compressor

WANG Chunjie, SONG Shunguang, ZONG Xiao

《能源前沿（英文）》 2008年 第2卷 第3期   页码 302-305 doi: 10.1007/s11708-008-0064-8

摘要： While a 3D assembly model of blade-disc structure was established, a finite element model for calculating the vibration characteristics during blade-disc coupling was built by taking into consideration the coupling action of contact stress between the blade and the disc. The vibration characteristics of the blade-disc coupling structure was calculated and analyzed using cycle analysis method with the aid of ANSYS software. The modeling experiment shows that this method is feasible for analyzing the rabbet assembly structure.

关键词： blade-disc coupling     assembly     experiment     vibration     blade-disc structure    

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Full-field dynamic strain reconstruction of an aero-engine blade from limited displacement responses

《机械工程前沿（英文）》 2023年 第18卷 第1期 doi: 10.1007/s11465-022-0731-1

摘要： Blade strain distribution and its change with time are crucial for reliability analysis and residual life evaluation in blade vibration tests. Traditional strain measurements are achieved by strain gauges (SGs) in a contact manner at discrete positions on the blades. This study proposes a method of full-field and real-time strain reconstruction of an aero-engine blade based on limited displacement responses. Limited optical measured displacement responses are utilized to reconstruct the full-field strain. The full-field strain distribution is in-time visualized. A displacement-to-strain transformation matrix is derived on the basis of the blade mode shapes in the modal coordinate. The proposed method is validated on an aero-engine blade in numerical and experimental cases. Three discrete vibrational displacement responses measured by laser triangulation sensors are used to reconstruct the full-field strain over the whole operating time. The reconstructed strain responses are compared with the results measured by SGs and numerical simulation. The high consistency between the reconstructed and measured results demonstrates the accurate strain reconstructed by the method. This paper provides a low-cost, real-time, and visualized measurement of blade full-field dynamic strain using displacement response, where the traditional SGs would fail.

关键词： aero-engine blade     displacement response     dynamic strain reconstruction     mode shape     strain gauge    

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New response surface model and its applications in aerodynamic optimization of axial compressor blade

LIU Xiaojia, NING Fangfei

《能源前沿（英文）》 2008年 第2卷 第4期   页码 541-549 doi: 10.1007/s11708-008-0077-3

摘要： A parametric method for the axial compressor 2D blade profiles is proposed in which the blade geometries are defined with the parameters commonly used for blade definition, which ensures that the geometric significance is clear and an unreasonable blade profile is not generated. Several illustrations are presented to show the fitting precision of the method. A novel response surface model is proposed which regards the objective distribution function in the vicinity of a sample as normal school, and then generates the response surface function in the whole design space by a linear combination of distribution functions of all the samples. Based on this model, a numerical aerodynamic optimization platform for the axial compressor 2D blade profiles is developed, by which aerodynamic optimization of two compressor blade profiles are presented.

关键词： definition     objective distribution     fitting precision     combination     numerical aerodynamic    

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Dynamic characteristics of a shrouded blade with impact and friction

Xumin GUO, Jin ZENG, Hui MA, Chenguang ZHAO, Lin QU, Bangchun WEN

《机械工程前沿（英文）》 2020年 第15卷 第2期   页码 209-226 doi: 10.1007/s11465-019-0566-6

摘要： A simplified computational model of a twisted shrouded blade with impact and friction is established. In this model, the shrouded blade is simulated by a flexible Timoshenko beam with a tip-mass, and the effects of centrifugal stiffening, spin softening, and Coriolis force are considered. Impact force is simulated using a linear spring model, and friction force is generated by a tangential spring model under sticking state and a Coulomb friction model under sliding state. The proposed model is validated by a finite element model. Then, the effects of initial gap and normal preload, coefficient of friction, and contact stiffness ratio (the ratio of tangential contact stiffness to normal contact stiffness) on system vibration responses are analyzed. Results show that resonant peaks become inconspicuous and impact plays a dominant role when initial gaps are large between adjacent shrouds. By contrast, in small initial gaps or initial normal preloads condition, resonant speed increases sharply, and the optimal initial normal preloads that can minimize resonant amplitude becomes apparent. Coefficient of friction affects the optimal initial normal preload, but it does not affect vibration responses when the contact between shrouds is under full stick. System resonant amplitude decreases with the increase of contact stiffness ratio, but the optimal initial normal preload is unaffected.

关键词： twisted shrouded blade     dynamic analysis     impact     friction     separate–stick–slip motion    

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Postprocessor development for ultrasonic cutting of honeycomb core curved surface with a straight blade

《机械工程前沿（英文）》 2023年 第18卷 第1期 doi: 10.1007/s11465-022-0729-8

摘要： When ultrasonically cutting honeycomb core curved parts, the tool face of the straight blade must be along the curved surface’s tangent direction at all times to ensure high-quality machining of the curved surface. However, given that the straight blade is a nonstandard tool, the existing computer-aided manufacturing technology cannot directly realize the above action requirement. To solve this problem, this paper proposed an algorithm for extracting a straight blade real-time tool face vector from a 5-axis milling automatically programmed tool location file, which can realize the tool location point and tool axis vector conversion from the flat end mill to the straight blade. At the same time, for the multi-solution problem of the rotation axis, the dependent axis rotation minimization algorithm was introduced, and the spindle rotation algorithm was proposed for the tool edge orientation problem when the straight blade is used to machine the curved part. Finally, on the basis of the MATLAB platform, the dependent axis rotation minimization algorithm and spindle rotation algorithm were integrated and compiled, and the straight blade ultrasonic cutting honeycomb core postprocessor was then developed. The model of the machine tool and the definition of the straight blade were conducted in the VERICUT simulation software, and the simulation machining of the equivalent entity of the honeycomb core can then be realized. The correctness of the numerical control program generated by the postprocessor was verified by machining and accuracy testing of the two designed features. Observation and analysis of the simulation and experiment indicate that the tool pose is the same under each working condition, and the workpieces obtained by machining also meet the corresponding accuracy requirements. Therefore, the postprocessor developed in this paper can be well adapted to the honeycomb core ultrasonic cutting machine tool and realize high-quality and high-efficient machining of honeycomb core composites.

关键词： honeycomb core     straight blade     ultrasonic cutting     tool pose     postprocessor    

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Nonlinear dynamic behavior of rotating blade with breathing crack

Laihao YANG, Zhu MAO, Shuming WU, Xuefeng CHEN, Ruqiang YAN

《机械工程前沿（英文）》 2021年 第16卷 第1期   页码 196-220 doi: 10.1007/s11465-020-0609-z

摘要： This study aims at investigating the nonlinear dynamic behavior of rotating blade with transverse crack. A novel nonlinear rotating cracked blade model (NRCBM), which contains the spinning softening, centrifugal stiffening, Coriolis force, and crack closing effects, is developed based on continuous beam theory and strain energy release rate method. The rotating blade is considered as a cantilever beam fixed on the rigid hub with high rotating speed, and the crack is deemed to be open and close continuously in a trigonometric function way with the blade vibration. It is verified by the comparison with a finite element-based contact crack model and bilinear model that the proposed NRCBM can well capture the dynamic characteristics of the rotating blade with breathing crack. The dynamic behavior of rotating cracked blade is then investigated with NRCBM, and the nonlinear damage indicator (NDI) is introduced to characterize the nonlinearity caused by blade crack. The results show that NDI is a distinguishable indicator for the severity level estimation of the crack in rotating blade. It is found that severe crack (i.e., a closer crack position to blade root as well as larger crack depth) is expected to heavily reduce the stiffness of rotating blade and apparently result in a lower resonant frequency. Meanwhile, the super-harmonic resonances are verified to be distinguishable indicators for diagnosing the crack existence, and the third-order super-harmonic resonances can serve as an indicator for the presence of severe crack since it only distinctly appears when the crack is severe.

关键词： rotating blade     breathing crack     nonlinear vibration     nonlinear damage indicator    

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Numerical simulation of a new hollow stationary dehumidity blade in last stage of steam turbine

Youmin HOU, Danmei XIE, Wangfan LI, Xinggang YU, Yang SHI, Hanshi QIN

《能源前沿（英文）》 2011年 第5卷 第3期   页码 288-296 doi: 10.1007/s11708-011-0160-z

摘要： As a result of adopting saturation steam and long blade, problems of water erosion of last stage blade for steam turbine become more prominent. In order to improve the operation reliability and efficiency of steam turbine, it is necessary to investigate the nonequilibrium condensing wet steam two phase flow and the dehumidity method. A wet steam model with user defined function based on FLUENT software was investigated to simulate the steam condensing flow in the cascades. The simulation consequences show that the pressure variations in simulation depict a good agreement with the experiment data. On the basis of the discrete phase model simulation results and experiment data, the efficiency of existing dehumidity blade with suction slot was calculated. A new stationary dehumidity blade was designed to elevate the dehumidity efficiency: the efficiency in the suction surface was increased by 21.5%, and that in the pressure surface was increased by 12.2%.

关键词： steam turbine     hollow stationary blade     dehumidity     numerical simulation    

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Mobile platform for hydraulic turbine blade repair robot

GUI Zhongcheng, CHEN Qiang, SUN Zhenguo, ZHANG Wenzeng, LIU Kang

《机械工程前沿（英文）》 2008年 第3卷 第2期   页码 164-169 doi: 10.1007/s11465-008-0035-0

摘要： The wall-climbing mobile platform (MP) of a robot for repairing a hydraulic turbine blade onsite is developed. The MP is equipped with ferromagnetic adhesive devices and can work on a spatial curved surface. The contradiction between mobility and load-bearing ability is analyzed, and the problem of self-adaptation to the curved face is solved using differential-driven wheeled locomotion with ferromagnetic adhesive devices. The platform adheres to the blade surface through the force provided by the ferromagnetic devices, and a certain gap exists between the magnetic devices and the blade’s surface. A mechanism of three revolution degrees of freedom, which connects the magnetic devices with the platform’s chassis, is developed to make the platform self-adapt to the complex curved surface of the turbine blade. A proof-of-principle prototype has been manufactured, and experiments prove the success of the MP. The payload of the zero-turn-radius MP with excellent maneuverability exceeds 80 kg. The platform can automatically adapt to complex spatial surfaces, which satisfy the requirements of a hydraulic turbine blade in-situ repair robot.
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Fixturing technology and system for thin-walled parts machining: a review

《机械工程前沿（英文）》 2022年 第17卷 第4期 doi: 10.1007/s11465-022-0711-5

摘要： During the overall processing of thin-walled parts (TWPs), the guaranteed capability of the machining process and quality is determined by fixtures. Therefore, reliable fixtures suitable for the structure and machining process of TWP are essential. In this review, the key role of fixtures in the manufacturing system is initially discussed. The main problems in machining and workholding due to the characteristics of TWP are then analyzed in detail. Afterward, the definition of TWP fixtures is reinterpreted from narrow and broad perspectives. Fixture functions corresponding to the issues of machining and workholding are then clearly stated. Fixture categories are classified systematically according to previous research achievements, and the operation mode, functional characteristics, and structure of each fixture are comprehensively described. The function and execution mode of TWP fixtures are then systematically summarized and analyzed, and the functions of various TWP fixtures are evaluated. Some directions for future research on TWP fixtures technology are also proposed. The main purpose of this review is to provide some reference and guidance for scholars to examine TWP fixtures.

关键词： thin-walled part (TWP)     fixture     machining     fixture categories     fixture function    

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A zone-layered trimming method for ceramic core of aero-engine blade based on an advanced reconfigurable

《机械工程前沿（英文）》 2022年 第17卷 第2期 doi: 10.1007/s11465-022-0675-5

摘要： Ceramic structural parts are one of the most widely utilized structural parts in the industry. However, they usually contain defects following the pressing process, such as burrs. Therefore, additional trimming is usually required, despite the deformation challenges and difficulty in positioning. This paper proposes an ultrafast laser processing system for trimming complex ceramic structural parts. Opto-electromechanical cooperative control software is developed to control the laser processing system. The trimming problem of the ceramic cores used in aero engines is studied. The regional registration method is introduced based on the iterative closest point algorithm to register the path extracted from the computer-aided design model with the deformed ceramic core. A zonal and layering processing method for three-dimensional contours on complex surfaces is proposed to generate the working data of high-speed scanning galvanometer and the computer numerical control machine tool, respectively. The results show that the laser system and the method proposed in this paper are suitable for trimming complex non-datum parts such as ceramic cores. Compared with the results of manual trimming, the method proposed in this paper has higher accuracy, efficiency, and yield. The method mentioned above has been used in practical application with satisfactory results.

关键词： ceramic parts trimming     computer-aided laser manufacturing     3D vision     reconfigurable laser processing system    

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Probability strength design of steam turbine blade and sensitivity analysis with respect to random parameters

DUAN Wei

《能源前沿（英文）》 2008年 第2卷 第1期   页码 107-115 doi: 10.1007/s11708-008-0018-1

摘要： Many stochastic parameters have an effect on the reliability of a steam turbine blade during practical operation. To improve the reliability of blade design, it is necessary to take these stochastic parameters into account. An equal cross-section blade is investigated and a finite element model is built parametrically. Geometrical parameters, material parameters and load parameters of the blade are considered as input random variables while the maximum deflection and maximum equivalent stress are output random variables. Analysis file of the blade is compiled by deterministic finite element method and applied to be loop file to create sample points. A quadratic polynomial with cross terms is chosen to regress these samples by step-forward regression method and employed as a surrogate of numerical solver to drastically reduce the number of solvers call. Then, Monte Carlo method is used to obtain the statistical characteristics and cumulative distribution function of the maximum deflection and maximum equivalent stress of the blade. Probability sensitivity analysis, which combines the slope of the gradient and the width of the scatter range of the random input variables, is applied to evaluate how much the output parameters are influenced by the random input parameters. The scatter plots of structural responses with respect to the random input variables are illustrated to analyze how to change the input random variables to improve the reliability of the blade. The results show that combination of the finite element method, the response surface method and Monte Carlo method is an ideal way for the reliability analysis and probability strength design of the blade.

关键词： Probability sensitivity     sensitivity analysis     number     cross-section     statistical    

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Centrifugal compressor blade optimization based on uniform design and genetic algorithms

SHU Xinwei, GU Chuangang, XIAO Jun, GAO Chuang

《能源前沿（英文）》 2008年 第2卷 第4期   页码 453-456 doi: 10.1007/s11708-008-0083-5

摘要： An optimization approach to centrifugal compressor blade design, incorporating uniform design method (UDM), computational fluid dynamics (CFD) analysis technique, regression analysis method and genetic algorithms (GA), is presented. UDM is employed to generate the geometric information of trial samples whose performance is evaluated by CFD technique. Then, function approximation of sample information is performed by regression analysis method. Finally, global optimization of the approximative function is obtained by genetic algorithms. Taking maximum isentropic efficiency as objective function, this optimization approach has been applied to the optimum design of a certain centrifugal compressor blades. The results, compared with those of the original one, show that isentropic efficiency of the optimized impeller has been improved which indicates the effectiveness of the proposed optimization approach.

关键词： information     computational     centrifugal compressor     regression analysis     CFD    

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A measurement system for thin elastohydrodynamic lubrication films

WANG Xuefeng, GUO Feng, YANG Peiran

《机械工程前沿（英文）》 2007年 第2卷 第2期   页码 193-196 doi: 10.1007/s11465-007-0032-8

摘要： An elastohydrodynamic lubrication (EHL) film measurement system using multi-beam interferometry is introduced in this paper. The measurement principle and the instrumentation are discussed. A simple and efficient method is suggested to obtain the fringe order of measured points. It is demonstrated that the presented measurement system can provide continuous measurement of lubricating films from nano to micro scales at a nano-level resolution, and can be used to investigate ultra-thin EHL films and tiny variations in EHL films.

关键词： instrumentation     continuous measurement     elastohydrodynamic lubrication     ultra-thin     measurement    

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标题 作者 时间 类型 操作

Investigation of vortical flows over oscillating body using fast Lagrangian vortex method

Baoshan ZHU ,

期刊论文

Hysteretic behavior of cambered surface steel tube damper: Theoretical and experimental research

期刊论文

Vibration analysis of blade-disc coupled structure of compressor

WANG Chunjie, SONG Shunguang, ZONG Xiao

期刊论文

Full-field dynamic strain reconstruction of an aero-engine blade from limited displacement responses

期刊论文

New response surface model and its applications in aerodynamic optimization of axial compressor blade

LIU Xiaojia, NING Fangfei

期刊论文

Dynamic characteristics of a shrouded blade with impact and friction

Xumin GUO, Jin ZENG, Hui MA, Chenguang ZHAO, Lin QU, Bangchun WEN

期刊论文

Postprocessor development for ultrasonic cutting of honeycomb core curved surface with a straight blade

期刊论文

Nonlinear dynamic behavior of rotating blade with breathing crack

Laihao YANG, Zhu MAO, Shuming WU, Xuefeng CHEN, Ruqiang YAN

期刊论文

Numerical simulation of a new hollow stationary dehumidity blade in last stage of steam turbine

Youmin HOU, Danmei XIE, Wangfan LI, Xinggang YU, Yang SHI, Hanshi QIN

期刊论文

Mobile platform for hydraulic turbine blade repair robot

GUI Zhongcheng, CHEN Qiang, SUN Zhenguo, ZHANG Wenzeng, LIU Kang

期刊论文

Fixturing technology and system for thin-walled parts machining: a review

期刊论文

A zone-layered trimming method for ceramic core of aero-engine blade based on an advanced reconfigurable

期刊论文

Probability strength design of steam turbine blade and sensitivity analysis with respect to random parameters

DUAN Wei

期刊论文

Centrifugal compressor blade optimization based on uniform design and genetic algorithms

SHU Xinwei, GU Chuangang, XIAO Jun, GAO Chuang

期刊论文

A measurement system for thin elastohydrodynamic lubrication films

WANG Xuefeng, GUO Feng, YANG Peiran

期刊论文