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H2/CO/air premixed and partially premixed flame structure at different pressures based on reaction limit analysis

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Science Bulletin 2018年第19期63卷 1260-1266页

作者： Zaigang Liu Wenjun Kong Jean-Louis Consalvi wenhu Han Key Laboratory of Light-Duty Gas-Turbine Institute of Engineering Thermophysics Chinese Academy of Sciences Beijing 100190 China School of Engineering Sciences. University of Chinese Academy of Sciences Beijing 100049 China IUSTI UMR 7343 Aix-Marseille Universite CNRS Marseille 13453 France

Premixed and partially premixed flames (PPFs) of H2/CO/air syngas are studied numerically to investigate the effect of pressure on syngas PPF structure. Chemical characteristics of the syngas flame at different pressures are investigated based on reaction limit analysis using a one-dimensional configuration. The results show that CO affects the syngas reaction limits through both physical effects that consist mainly in dilution and chemical effects that are related to both R23 (CO+OH=CO2+H) and HCO pathway. In particular, the HCO pathway weakens the flame at low pressures due to the chain-terminating effect of R25 (HCO+O2=CO+HO2) and R26 (HCO+H=CO+H2), and enhances the flame at high pressures because of the contribution of R25 to the HO2chain-branching process. These CO chemical characteristics are also observed in the premixed zone of 50%H2+50%CO syngas PPFs whereas only R23 is important in the non-premixed zone.

关键词： Syngas Partially premixed flame Pressure effect Reaction limit Flame structure

Wave localization in randomly disordered periodic layered piezoelectric structures

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Acta Mechanica Sinica 2006年第6期22卷 559-567页

作者： Fengming Li Yuesheng Wang Chao Hu wenhu Huang Department of Aerospace Science and Mechanics Harbin Institute of Technology Harbin 150001 China Institute of Engineering Mechanics Beijing Jiaotong University Beijing 100044 China School of Aerospace Engineering and Mechanics TongJi University Shanghai 200092 China Department of Aerospace Engineering and Mechanics Harbin Institute of Technology Harbin 150001 China

Considering the mechnoelectrical coupling, the localization of SH-waves in disordered periodic layered piezoelectric structures is studied. The waves propagating in directions normal and tangential to the layers are considered. The transfer matrices between two consecutive unit cells are obtained according to the continuity conditions. The expressions of localization factor and localization length in the disordered periodic structures are presented. For the disordered periodic piezoelectric structures, the numerical results of localization factor and localization length are presented and discussed. It can be seen from the results that the frequency passbands and stopbands appear for the ordered periodic structures and the wave localization phenomenon occurs in the disordered periodic ones, and the larger the coefficient of variation is, the greater the degree of wave localization is. The widths of stopbands in the ordered periodic structures are very narrow when the properties of the consecutive piezoelectric materials are similar and the intervals of stopbands become broader when a certain material parameter has large changes. For the wave propagating in the direction normal to the layers the localization length has less dependence on the frequency, but for the wave propagating in the direction tangential to the layers the localization length is strongly dependent on the frequency.

关键词： Disordered periodic layered piezoelectric structures Transfer matrix Lyapunov exponent Localization factor Localization length

A wall-thickness compensation strategy for wax pattern of hollow turbine blade

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Chinese Journal of Aeronautics 2019年第8期32卷 1982-1993页

作者： Kang CUI wenhu WANG Ruisong JIANG Dezhong ZHAO Key Laboratory of Contemporary Design and Integrated Manufacturing Technology Ministry of EducationNorthwestern Polytechnical University

As an important index affecting the aerodynamic performance and the structural strength of hollow turbine blades, the wall-thickness precision of the blade is mainly inherited from the positional relationship between the corresponding wax pattern and the internal ceramic ***, due to locating errors, the actual position of ceramic core is always deviated from the ideal position, which makes it difficult to guarantee the wall-thickness precision of the wax *** solve this problem, a wall-thickness compensation strategy is proposed in this paper. Firstly,based on the industrial computed tomography(ICT) technique and curve matching algorithms, a model reconstruction method is developed, with which the 3D model of a trial wax pattern can be easily constructed. After that, focusing on eliminating the wall-thickness errors of the trial wax pattern, an optimization method for the pose of the ceramic core in the wax pattern is proposed. Then, by mapping the optimal pose of the ceramic core to length adjustments of the locating rods, the wall-thickness errors of the wax pattern can be greatly reduced. A case study is also given to illustrate the effectiveness of the proposed compensation strategy.

关键词： Hollow turbine blade Locating compensation Model reconstruction Pose optimization Wax pattern Wall-thickness error

Impact of lubricant traction coefficient on cage's dynamic characteristics in high-speed angular contact ball bearing

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Chinese Journal of Aeronautics 2017年第2期30卷 827-835页

作者： Zhang wenhu Deng Sier Chen Guoding Cui Yongcun School of Mechatronics Engineering Northwestern Polytechnical University Xi'an 710071 China School of Mechatronics Engineering Henan University of Science and Technology Luoyang 471003 China Collaborative Innovation Center of Major Machine Manufacturing in Liaoning Dalian 116024 China

In this paper,the formulas of elasto-hydrodynamic traction coefficients of three Chinese aviation lubricating oils,4109,4106 and 4050,were obtained by a great number of elastohydrodynamic traction *** nonlinear dynamics differential equations of high-speed angular contact ball bearing were built on the basis of dynamic theory of rolling bearings and solved by Gear Stiff（GSTIFF） integer algorithm with variable *** impact of lubricant traction coefficient on cage＇s dynamic characteristics in high-speed angular contact ball bearing was investigated,and Poincare map was used to analyze the impact of three types of aviation lubricating oils on the dynamic response of cage＇s mass *** then,the period of dynamic response of cage＇s mass center and the slip ratio of cage were used to assess the stability of cage under various working *** results of this paper provide the theoretical basis for the selection and application of aviation lubricating oil.

关键词： Dynamic characteristic High-speed angular contact ball bearing Lubricant traction coefficient Poincare map Stability

Quantitative sufficient conditions for adiabatic approximation

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Science China(Physics,Mechanics & Astronomy) 2013年第7期56卷 1401-1407页

作者： CAO HuaiXin GUO ZhiHua CHEN ZhengLi WANG wenhu College of Mathematics and Information Science Shaanxi Normal University

Two linear In this letter, we prove the following conclusions by introducing a function Fn（t）：（1） If a quantum system S with a time-dependent non-degenerate Hamiltonian H（t） is initially in the n-th eigenstate of H（0）, then the state of the system at time t will remain in the n-th eigenstate of H（t） up to a multiplicative phase factor if and only if the values Fn（t） for all t are always on the circle centered at 1 with radius 1; （2） If a quantum system S with a time-dependent Hamiltonian H（t） is initially in the n-th eigenstate of H（0）, then the state of the system at time t will remain c-uniformly approximately in the n-th eigenstate of H（t） up to a multiplicative phase factor if and only if the values F,（t） for all t are always outside of the circle centered at 1 with radius 1-ε. Moreover, some quantitative sufficient conditions for the state of the system at time t to remain ε-uniformly approximately in the n-th eigenstate of H（t） up to a multiplicative phase factor are established. Lastly, our results are illustrated by a spin-half particle in a rotating magnetic field.

关键词： quantitative condition adiabatic approximation uniformly slowly evolving 6-uniformly slowly evolving

Bifurcation and chaos of the bladed overhang rotor system with squeeze film dampers

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Science China(Technological Sciences) 2009年第3期52卷 709-720页

作者： CAO DengQing WANG LiGang CHEN YuShu HUANG wenhu School of Astronautics Harbin Institute of TechnologyHarbin 150001China

To study the nonlinear dynamic behavior of the bladed overhang rotor system with squeeze film damper (SFD), a blade-overhang rotor-SFD model is formulated using the lumped mass method and the Lagrange approach. The cavitated short bearing model is employed to describe the nonlinear oil force of the SFD. To reduce the scale of the nonlinear coupling system, a set of orthogonal transformations is employed to decouple the one nodal diameter equations of blades, which are coupled with the dy- namical equations of the rotor, with other equations of blades. In this way, the original system with 16+4n (n≥3) degrees of freedom (DoF) is reduced to a system with 24 DoF only. Then the parametric excitation terms in the blade-overhang rotor-SFD model are simplified in terms of periodic transforma- tions. The coupling equations are numerically solved and the solutions are used to analyze the dy- namic behavior of the system in terms of the bifurcation diagram, whirl orbit, Poincaré map and spec- trum plot. A variety of motion types are found such as multi-periodic, quasi-periodic, and chaotic mo- tions. Moreover, the typical nonlinear dynamic evolutions including the periodic-doubling bifurcation and reverse bifurcation are noted. It is noticed that there exist apparent differences in the dynamic behavior between the blade-overhang rotor-SFD models without and with considering the effect of blades.

关键词： bladed overhang rotor system squeeze film damper bifurcation chaos

Experimental study on impact of roller imbalance on cage stability

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Chinese Journal of Aeronautics 2021年第10期34卷 248-264页

作者： Yongcun CUI Sier DENG Kaiwen DENG Hui LIAO wenhu ZHANG School of Information Engineering Henan University of Science ami TechnologyLuoyang 471003China Post-Doctoral Workstation Bcihucm Technology Group Co..LtdTaizhou 318000China School of Mcchatronics Engineering Henan University of Science and TechnologyLuoyang 471003China School of Mechanical Engineering Northwestern Po/ytechnical UniversityXi'an 710071China

This study presents a method for measuring the imbalance in a small-sized cylindrical *** roller imbalance was calibrated on the built static-pressure-air flotation measurement *** impact of the roller imbalance on the dynamic characteristics of a cage were then studied on the aero-bearing test *** displacement spectrums with different roller imbalance of the obtained cage orbits under various bearing speed and radial load were used to evaluate the cage *** results show that the cage cannot form a stable operating state at a lower bearing speed with or without the unbalanced *** cage with balanced rollers gradually develops stable motion with the increase of the bearing *** existence of a small roller imbalance causes the stability of the cage to *** an increase in the bearing speed and radial load,the cage with the unbalanced rollers runs unsteadily accompanied by a high-frequency vibration when the roller imbalance is large *** vibration amplitude of the cage in the horizontal direction is greater than that in the vertical direction during an unstable operation,which is similar in the stable status.

关键词： Cage orbits Cage stability Experimental study High-speed cylindrical roller bearing Roller imbalance Spectrum Vibration

SCATTERING OF ELASTIC WAVES IN AN ELASTIC MATRIX CONTAINING AN INCLUSION WITH INTERFACES

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Acta Mechanica Solida Sinica 2002年第3期15卷 270-276页

作者： Li Fengming Hu Chao Huang wenhu Harbin Inst Technol Dept Aerosp Engn & Mech Harbin 150001 Peoples R China

Based on the theory of elastic dynamics, the scattering of elasticwaves and dynamic stress concentration of fiber-reinforced compositewith interfaces are studied. Analytical expressions of elastic wavesin different medium areas are presented and an analytic method ofsolving this problem is established. The mode coefficients aredetermined by means of the continuous conditions of displacement andstress on the boundary of the interfaces. The influence of materialproperties and structural size on the dynamic stress con- centrationfactors near the interfaces is analyzed.

关键词： fibre-reinforced composite interfaces scattering of elastic waves dynamicstress concen- tration

Synergistic effect of various elements in Fe_(41)Co_(7)Cr_(15)Mo_(14)C_(15)B_(6)Y_(2) amorphous alloy hollow ball on catalytic degradation of methylene blue

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Journal of Rare Earths 2022年第4期40卷 605-615,I0004页

作者： wenhu Luo Qingjun Chen Li Ji Xinyuan Peng Guosheng Huang School of Materials Science and Engineering Nanchang Hongkong UniversityNanchang 330063China State Key Laboratory for Marine Corrosion and Protection Luoyang Ship Material Research Institute(LSMRI)Qingdao 266237China

Metallic glasses have recently attracted great attention in terms of degrading dyes and other organic pollutants as an environmentally friendly material for wastewater ***,we report a new type of amorphous catalyst Fe_(41)Co_(7)Cr_(15)Mo_(14)C_(15)B_(6)Y_(2) hollow *** demonstrate that the catalyst can still completely decolorize the 20 mg/L methylene blue(MB)solution after reused for 50 times under conditions of pH=5,catalyst content 0.5 g/L,and temperature 80°*** catalyst is easily broken during degradation,so the inner surface also provides additional active *** Fe_(41)Co_(7)Cr_(15)Mo_(14)C_(15)B_(6)Y_(2) amorphous alloy hollow balls were characterized by energy dispersive X-ray specroscopy(EDS),scanning electron microscopy(SEM)and X-ray photoelectron spectroscopy(XPS),*** elements in the catalytic system have a synergistic catalytic *** cycle Fe^(2+)/Fe^(3+),Co^(2+)/Co^(3+)and Mo^(4+)/Mo^(6+) promote mutual conversion and accelerate the catalytic process of their reaction with H_(2)O_(2),forming a self-stable redox cycle *** them,Fe^(2+)promotes the conversion of Co^(3+)to Co^(2+),and Mo^(4+) promotes the conversion of Fe^(3+)to Fe^(2+),mainly Fe^(2+)and Co^(2+)react with H_(2)O_(2) to generate•*** and Cr elements form MoO_(2) and Cr_(2)O_(3) plasma compounds on the surface,which act as a protective film to make the catalyst more stable and be repeated used more frequently.

关键词： Metallic glasses Methylene blue degradation Synergistic catalytic Repeatability Hollow ball Rare earths