The aerodynamic and centrifugal loads acting on the rotating blade make the blade configuration deformed comparing to its shape at rest. Accurate prediction of the running blade configuration plays a significant role ...The aerodynamic and centrifugal loads acting on the rotating blade make the blade configuration deformed comparing to its shape at rest. Accurate prediction of the running blade configuration plays a significant role in examining and analyzing turbomachinery performance. Considering nonlinear stiffness and loads, a reconstruction method is presented to address transformation of a rotating blade from cold to hot state. When calculating blade deformations, the blade stiffness and load conditions are updated simultaneously as blade shape varies. The reconstruction procedure is iterated till a converged hot blade shape is obtained. This method has been employed to determine the operating blade shapes of a test rotor blade and the Stage 37 rotor blade. The calculated results are compared with the experiments. The results show that the proposed method used for blade operating shape prediction is effective. The studies also show that this method can improve precision of finite element analysis and aerodynamic performance analysis.展开更多
Comprehensive information on geographic patterns of leaf morphological traits in Chinese forests is still scarce.To explore the spatial patterns of leaf traits,we investigated leaf area(LA),leaf thickness(LT),specific...Comprehensive information on geographic patterns of leaf morphological traits in Chinese forests is still scarce.To explore the spatial patterns of leaf traits,we investigated leaf area(LA),leaf thickness(LT),specific leaf area(SLA),and leaf dry matter content(LDMC) across 847 species from nine typical forests along the North-South Transect of Eastern China(NSTEC) between July and August 2013,and also calculated the community weighted means(CWM) of leaf traits by determining the relative dominance of each species.Our results showed that,for all species,the means(± SE) of LA,LT,SLA,and LDMC were 2860.01 ± 135.37 mm2,0.17 ± 0.003 mm,20.15 ± 0.43 m2 kg–1,and 316.73 ± 3.81 mg g–1,respectively.Furthermore,latitudinal variation in leaf traits differed at the species and community levels.Generally,at the species level,SLA increased and LDMC decreased as latitude increased,whereas no clear latitudinal trends among LA or LT were found,which could be the result of shifts in plant functional types.When scaling up to the community level,more significant spatial patterns of leaf traits were observed(R2 = 0.46–0.71),driven by climate and soil N content.These results provided synthetic data compilation and analyses to better parameterize complex ecological models in the future,and emphasized the importance of scaling-up when studying the biogeographic patterns of plant traits.展开更多
A rotating cantilever sandwich-plate model with a pre-twisted and pre-set angle has been developed to investigate the vibrational behavior of an aero-engine turbine blade with thermal barrier coating(TBC) layers. The ...A rotating cantilever sandwich-plate model with a pre-twisted and pre-set angle has been developed to investigate the vibrational behavior of an aero-engine turbine blade with thermal barrier coating(TBC) layers. The classic von Karman plate theory and the first-order shear deformation theory are applied to derive the energy equations of the rotating TBC blade, in which the geometric shapes, the work ambient temperature, and the TBC material properties are considered. The Chebyshev-Ritz method is used to obtain the nature frequency of the rotating TBC blade. For static frequency and modal analysis, the finite-element method(FEM)is also applied to compare and validate the results from the Chebyshev-Ritz method. A good agreement is found among these kinds of methods. For dynamic frequency, the results are analyzed in detail concerning the influence of system parameters such as the thickness of the TBC layer, the working temperature, and the pre-twisted and pre-set angle. Finally, the Campbell diagram is demonstrated to analyze the resonance property of the cantilever sandwich TBC blade model.展开更多
基金supported by National Natural Science Foundation of China,Grant No.51606023 and 51436002Natural Science Foundation of Liaoning Province,Grant No.2015020130Fundamental Research Funds for the Central Universities,Grant No.3132017015
文摘The aerodynamic and centrifugal loads acting on the rotating blade make the blade configuration deformed comparing to its shape at rest. Accurate prediction of the running blade configuration plays a significant role in examining and analyzing turbomachinery performance. Considering nonlinear stiffness and loads, a reconstruction method is presented to address transformation of a rotating blade from cold to hot state. When calculating blade deformations, the blade stiffness and load conditions are updated simultaneously as blade shape varies. The reconstruction procedure is iterated till a converged hot blade shape is obtained. This method has been employed to determine the operating blade shapes of a test rotor blade and the Stage 37 rotor blade. The calculated results are compared with the experiments. The results show that the proposed method used for blade operating shape prediction is effective. The studies also show that this method can improve precision of finite element analysis and aerodynamic performance analysis.
基金National Natural Science Foundation of China,No.31290221,No.31470506Chinese Academy of Sciences Strategic Priority Research Program,No.XDA05050702Program for Kezhen Distinguished Talents in Institute of Geographic Sciences and Natural Resources Research,CAS,No.2013RC102
文摘Comprehensive information on geographic patterns of leaf morphological traits in Chinese forests is still scarce.To explore the spatial patterns of leaf traits,we investigated leaf area(LA),leaf thickness(LT),specific leaf area(SLA),and leaf dry matter content(LDMC) across 847 species from nine typical forests along the North-South Transect of Eastern China(NSTEC) between July and August 2013,and also calculated the community weighted means(CWM) of leaf traits by determining the relative dominance of each species.Our results showed that,for all species,the means(± SE) of LA,LT,SLA,and LDMC were 2860.01 ± 135.37 mm2,0.17 ± 0.003 mm,20.15 ± 0.43 m2 kg–1,and 316.73 ± 3.81 mg g–1,respectively.Furthermore,latitudinal variation in leaf traits differed at the species and community levels.Generally,at the species level,SLA increased and LDMC decreased as latitude increased,whereas no clear latitudinal trends among LA or LT were found,which could be the result of shifts in plant functional types.When scaling up to the community level,more significant spatial patterns of leaf traits were observed(R2 = 0.46–0.71),driven by climate and soil N content.These results provided synthetic data compilation and analyses to better parameterize complex ecological models in the future,and emphasized the importance of scaling-up when studying the biogeographic patterns of plant traits.
基金supported by the National Natural Science Foundation of China(Grant Nos.11272016&11290152)the Beijing Municipal Commission of Educationthe Ri-Xin Talents Project of Beijing University of Technology
文摘A rotating cantilever sandwich-plate model with a pre-twisted and pre-set angle has been developed to investigate the vibrational behavior of an aero-engine turbine blade with thermal barrier coating(TBC) layers. The classic von Karman plate theory and the first-order shear deformation theory are applied to derive the energy equations of the rotating TBC blade, in which the geometric shapes, the work ambient temperature, and the TBC material properties are considered. The Chebyshev-Ritz method is used to obtain the nature frequency of the rotating TBC blade. For static frequency and modal analysis, the finite-element method(FEM)is also applied to compare and validate the results from the Chebyshev-Ritz method. A good agreement is found among these kinds of methods. For dynamic frequency, the results are analyzed in detail concerning the influence of system parameters such as the thickness of the TBC layer, the working temperature, and the pre-twisted and pre-set angle. Finally, the Campbell diagram is demonstrated to analyze the resonance property of the cantilever sandwich TBC blade model.
