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Theoretical Investigation of Operation Modes of MHD Generators for Energy-bypass Engines

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Journal of Thermal Science 2014年第6期23卷 580-585页

作者： Jingfeng Tang Nan Li daren yu Harbin Institute of Technology

A MHD generator with different arrangements of electromagnetic fields will lead the generator working in three modes.A quasi-one-dimensional approximation is used for the model of the MHD generator to analyze the inner mechanism of operation *** the MHD generator with a uniform constant magnetic field,a specific critical electric field E_(cr) is required to decelerate a supersonic entrance flow into a subsonic exit ***,the generator works in a steady mode with a larger electric field than E_(cr) in which a steady supersonic flow is provided at the exit,or the generator works in a choked mode with a smaller electric field than E_(cr) in which the supersonic entrance flow is choked in the *** detailed flow field characteristics in different operation modes are discussed,demonstrating the relationship of operation modes with electromagnetic fields.

关键词： Energy-bypass engines MHD generators Operation modes

Catastrophe,hysteresis and bifurcation of mode transition in scramjet engines and its model

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Science China(Technological Sciences) 2009年第6期52卷 1543-1550页

作者： yu daren CUI Tao BAO Wen Harbin Institute of Technology Harbin 150001China

This paper describes a class of nonlinear phenomena existing in the hypersonic flow and supersonic combustion process of scramjet engines:catastrophe,hysteresis and bifurcation,and further finds out the general rules(topological invariance)for the stability boundaries of mode transition in scramjet *** this topological invariance,a topological approach is put forward to model the stability boundaries,which may contribute to a complexity reduction of high-dimensional modeling when con-sidering more perturbation parameters,and help to explore the physical laws of the nonlinear ***,this paper interprets the characteristic of combustion mode transition based on the cusp topological model in singular theories,and observes the bifurcation characteristic in com-bustion mode ***,a modeling approach is proposed to mathematically describe the stability boundaries of combustion mode transition in scramjet engines,and the model has high ac-curacy comparing to the simulation data,which proves the validation of the basic ideas proposed in this ***,future research directions are proposed.

关键词： scramjet engine catastrophe bifurcation model

Gain Scheduling Control of Nonlinear Shock Motion Based on Equilibrium Manifold Linearization Model

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Chinese Journal of Aeronautics 2007年第6期20卷 481-487页

作者： Cui Tao yu daren Bao Wen Yang Yongbin College of Energy Science and Engineering Harbin Institute of Technology Harbin 150001 China

The equilibrium manifold linearization model of nonlinear shock motion is of higher accuracy and lower complexity over other models such as the small perturbation model and the piecewise-linear model. This paper analyzes the physical significance of the equilibrium manifold linearization model, and the self-feedback mechanism of shock motion is revealed. This helps to describe the stability and dynamics of shock motion. Based on the model, the paper puts forwards a gain scheduling control method for nonlinear shock motion. Simulation has shown the validity of the control scheme.

关键词： shock motion equilibrium manifold linearization gain scheduling control

Magnet stage optimization of 5 kW multi-cusped field thruster

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Plasma Science and Technology 2020年第9期22卷 128-138页

作者： Peng HU daren yu Yan SHEN Beijing Institute of Control Engineering Beijing 100094People's Republic of China Lab of Advanced Space Propulsion Beijing 100094People’s Republic of China Beijing Engineering Research Center of Efficient and Green Aerospace Propulsion Technology Beijing 100094People’s Republic of China Plasma Propulsion Laboratory of Harbin Institute of Technology Harbin 150001People's Republic of China School of Aeronautics and Astronautics Sun Yat-sen UniversityGuangzhou 510006People's Republic of China

The multi-cusped field thruster is a unique electric thruster device,which has many advantages such as long lifetime,large-range thrust throttling ability,high thrust density,and low *** thruster employs several alternating polarity permanent magnets to create a periodic magnetic field with several *** studies have indicated that the basic ionization and acceleration processes are directly related to the electron motion behavior,which mainly depends on the magnetic field *** magnet number and magnet stage length are two key magnetic field parameters that have important effects on the thruster *** this paper,both the magnet number and magnet stage length parameters are studied for the optimization of a 5 k W multi-cusped field *** results indicate that the three-stage thruster has a better electron confinement than the two-stage *** has lower ion energy loss at the wall,and shows a higher ionization ***,the three-stage magnetic field is a superior magnetic field ***,the three-stage magnetic field simulation results indicate that an optimal accelerating electric field distribution and ionization region distribution could be obtained when the magnet length ratio is 78:25:20.

关键词： multi-cusped field magnet number magnet length performance optimization

Impact of exterior electron emission on the self-sustaining margin of hollow cathode discharge

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Plasma Science and Technology 2020年第9期22卷 2-11页

作者： Tianhang MENG Zhongxi NING daren yu Harbin Institute of Technology Harbin 150001.People's Republic of China

Hollow cathode researches used to focus on the inner cavity or downstream plume,however,rarely on the gap between the throttling orifice plate and the keeper plate(T-K gap),which was found to impact the self-sustaining margin of hollow cathode discharge in this *** the lower margin,the main power deposition and electron emission and ionization regions would migrate from inner cavity and downstream plume to the T-K gap,in which case,the source and destination of each m A current therein matter for the self-sustaining *** the metal surfaces in the T-K gap with emissive materials proved effective in lowering the lower margin by supplementing auxiliary thermionic emission,compensating electron loss on cold absorbing walls and suppressing discharge *** doing so,the lower margin of a 4 A hollow cathode was lowered from 1 to 0.1-0.2 A,enabling it to couple with low power Hall thruster without extra keeper current.

关键词： hollow cathode self-sustained discharge secondary electron emission ionization oscillations thermionic emission

Swallowtail model for predicting the global bifurcation behavior of CO oxidation reactions

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Science China Chemistry 2011年第7期54卷 1072-1077页

作者： CUI Tao TANG ShunLin ZHANG Lei yu daren School of Energy Science and Engineering Harbin Institute of Technology Harbin 150001 China Pharmaceutical College Heilongjiang University of Chinese Medicine Institution Harbin 150040 China

Catalytic CO oxidation on platinum group metals exhibits nonlinear phenomena such as hysteresis and *** of the nonlinear mechanisms is important for catalyst design and control of reaction *** studies have offered initial insights into the local bifurcation behavior of CO ***,since the bifurcation behavior of CO oxidation is determined by multiple parameters such as temperature,total flux,and CO fraction,it is difficult to predict the global bifurcation behavior in the resulting high-dimensional parameter *** is for this reason that the observed nonlinear phenomena reflect just the local bifurcation features of CO *** this paper,an elementary chemical law(topological invariance) concerning the bifurcation behavior of CO oxidation on platinum group metals such as Pd(111) is found from a topological *** the elementary law,we put forward a topological approach to model the critical criteria for the reaction hysteresis and *** model may be applied to predict the global bifurcation behavior of CO oxidation in the high-dimensional parameter *** topological approach and the model results may be useful as a guide in thinking about the complex reaction mechanism,designing reaction routes,and actively controlling the bifurcation behavior of the CO oxidation reaction.

关键词： CO oxidation bifurcation hysteresis

Diagnostic and modelling investigation on the ion acceleration and plasma throttling effects in a dualemitter hollow cathode micro-thruster

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Chinese Journal of Aeronautics 2021年第12期34卷 85-98页

作者： Zhongxi NING Chenguang LIU Ximing ZHU Yanfei WANG Bingjian AN daren yu Plasma Propulsion Laboratory Harbin Institute of TechnologyHarbin 150001China

Hollow cathode discharges are widely used as neutralizers for the electric propulsion systems and recently developed into micro-thrusters for the small *** this work,a dualemitter hollow cathode thruster is developed,which can be operated in two different modes—the neutralizer mode and the micro-thruster *** characterizing this kind of new device,the Langmuir probe,Faraday probe,and retarding potential analyzer are used to determine the electron temperature,electron density,ion flux,and ion energy distribution *** operating parameters,including the thrust,and specific impulse,are also measured.A two-dimensional self-consistent extended fluid model is employed to calculate the spatial distribution of plasma parameters and the fluid field of electrons in the region around the *** comparing the diagnostic and modelling results,it is found that the change in the electric field and ionization zone is the essential reason for the different performances of the device in the neutralizer and micro-thruster *** in the electric field leads to an ion acceleration effect in the micro-thruster mode;moving of the ionization zone raises the plasma pressure in the orifice region of the hollow cathode,and thus leads to enhanced plasma throttling and gas expanding *** analyzing the above mechanisms,the possible methods for improving this kind of hollow cathode micro-thruster are discussed.

关键词： Extended fluid model Hollow cathodes Micro-thruster Plasma contactor Plasma throttling effect

Investigating the impacts of spatial-temporal variation features of air density on assessing wind power generation and its fluctuation in China

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Science China(Technological Sciences) 2023年第6期66卷 1797-1814页

作者： REN GuoRui WANG Wei WAN Jie HONG Feng YANG Ke yu daren School of Control and Computer Engineering North China Electric Power UniversityBeijing 102206China School of Electrical Engineering and Automation Harbin Institute of TechnologyHarbin 150001China Xi’an Thermal Power Research Institute Co. Ltd.Xi’an 710054China School of Energy Science and Engineering Harbin Institute of TechnologyHarbin 150001China

Air density plays an important role in assessing wind *** density significantly fluctuates both spatially and *** literature typically used standard air density or local annual average air density to assess wind *** present study investigates the estimation errors of the potential and fluctuation of wind resource caused by neglecting the spatial-temporal variation features of air density in *** air density at 100 m height is accurately calculated by using air temperature,pressure,and *** spatial-temporal variation features of air density are firstly *** the wind power generation is modeled based on a 1.5 MW wind turbine model by using the actual air density,standard air densityρst,and local annual average air densityρsite,***ρstoverestimates the annual wind energy production(AEP)in 93.6%of the study *** significantly affects AEP in central and southern China *** more than 75%of the study area,the winter to summer differences in AEP are underestimated,but the intra-day peak-valley differences and fluctuation rate of wind power are ***ρsitesignificantly reduces the estimation error in *** AEP is still overestimated(0-8.6%)in summer and underestimated(0-11.2%)in *** for southwest China,it is hard to reduce the estimation errors of winter to summer differences in AEP by usingρ***ρsitedistinctly reduces the estimation errors of intra-day peak-valley differences and fluctuation rate of wind power,but these estimation errors cannot be ignored as *** impacts of air density on assessing wind resource are almost independent of the wind turbine types.

关键词： air density spatial-temporal variation power curve wind resource assessment fluctuation ERA-5

Thermodynamic analysis for a chemically recuperated scramjet

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Science China(Technological Sciences) 2012年第11期55卷 3204-3212页

作者： QIN Jiang BAO Wen ZHANG SiLong SONG yuFei yu daren Harbin Institute of Technology Harbin 150001China

Endothermic hydrocarbon fuel is regarded as an optimal fuel for a scramjet with regenerative cooling,which provides extra cooling through endothermic chemical conversion to avoid the severly limited cooling capacity when conventional fuels are adopted for *** endothermic cooling is proposed from the view point that the heat sink of a conventional fuel is insufficient,the heat-absorbing through endothermic chemical reaction is actually a chemical recuperation process because the wasted heat dissipated from the engine thermal structure is recovered through the endothermic chemical ***,the working process of a scramjet with endothermic hydrocarbon fuel cooling is a chemical recuperative *** analyze the chemical recuperative cycle of a chemically recuperated scramjet engine,we defined physical and chemical recuperation effectivenesses and heating value increment rate,and derived engine performance parameters with chemical *** heat value benefits from both physical and chemical recuperations,and it increases with the increase in recuperation *** scramjet performance parameters also increase with the increase in chemical recuperation *** increase in chemical recuperation effectiveness improves both the performances of the fuel cooling system and the combustion *** results of analysis prove that the existence of a chemical recuperation process greatly improves the performance of the whole scramjet.

关键词： scramjet endothermic hydrocarbon fuel chemical recuperation regenerative cooling chemical reaction