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Multi-dimensional Modeling of the Application of Catalytic Combustion to Homogeneous Charge Compression Ignition Engine

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Journal of Thermal Science 2006年第4期15卷 371-376页

作者： Wen Zeng maozhao xie Department of Power Engineering Dalian University of Technology Dalian 116024 China

The detailed surface reaction mechanism of methane on rhodium catalyst was analyzed. Comparisons between numerical simulation and experiments showed a basic agreement. The combustion process of homogeneous charge compression ignition （HCCI） engine whose piston surface has been coated with catalyst （rhodium and platinum） was numerically investigated. A multi-dimensional model with detailed chemical kinetics was built. The effects of catalytic combustion on the ignition timing, the temperature and CO concentration fields, and HC, CO and NOx emissions of the HCCI engine were discussed. The results showed the ignition timing of the HCCI engine was advanced and the emissions of HC and CO were decreased by the catalysis.

关键词： catalytic combustion homogeneous charge compression ignition(HCCI) CFD methane detailed chemical kinetics.

Numerical Simulation of Double-diffusive Dynamical Model of a Solar Pond Considering the Effect of Turbidity and Wind

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Journal of Thermal Science 2006年第2期15卷 168-174页

作者： maozhao xie Shaocheng GE Wence SUN Power Engineering Department Dalian University of Technology Dalian 116024 China Department of Resource and Environment Engineering Liaoning Technical University Fuxin 123000China

A solar pond, typical double-diffusive system, is a stable heat source that can collect and store the solar energy. When the thermal stable condition is not satisfied at the interface, the upper and lower convective zone （UCZ and LCZ） will erode the middle non-convective zone （NCZ）, resulting in a drop or even a collapse of the thermal performance of solar pond. Wind strongly affects the erosion of NCZ from the entrainment of UCZ. The double-diffusion of heat and salt plays an important role in the erosion of NCZ from the entrainment of the lower-convective zone （LCZ）. The turbidity of saline water in the pond not only could lower the thermal performance of solar pond, but have effect on the entrainment mechanism. In this paper, based on the double-diffusive model along with the wind-driven turbulent entrainment model, the effects of turbidity and external wind etc. on the thermal performance of solar pond and the entrainment mechanism are analyzed with the numerical simulation.

关键词： solar pond wind double-diffusion turbidity erosion

Numerical study on the compression ignition of a porous medium engine

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Science China(Technological Sciences) 2008年第3期51卷 277-287页

作者： ZHAO ZhiGuo xie maozhao School of Energy and Power Engineering Dalian University of TechnologyDalian 116024China

Homogeneous and stable combustion can be realized in a porous medium (PM) engine where a chemically inert PM is mounted in the combustion chamber. To understand the mechanism of the PM engine, we simulated the working process of a PM engine fueled with natural gas (CH4) using an improved version of KIVA-3V and investigated the effects of the initial PM temperature, the PM structure as well as the fuel injection timing on the compression ignition of the engine. The im- proved version of KIVA-3V was verified by simulating the experiment of Zhdanok et al. for the superadiabatic combustion of CH4-air mixtures under filtration in a packed bed. The numerical results are in good agreement with experimental data for the speed of combustion wave. Computational results for the PM engine show that the initial PM temperature is the key factor in guaranteeing the onset of com- pression ignition of the PM engine at a given compression ratio. The PM structure affects greatly both convective heat transfer between the gas and solid phase in the PM and the dispersion effect of the PM. Pore diameter of the PM is a crucial factor in determining the realization of combustion in the PM engine. Over-late fuel injec- tion timing (near TDC) cannot assure a compression ignition of the PM engine.

关键词： PM engine CH4 KIVA-3V compression ignition numerical simulation

Bifurcation behaviors of catalytic combustion in a micro-channel

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Journal of Thermal Science 2008年第1期17卷 84-89页

作者： Wen Zeng maozhao xie Hongan Ma Wei Xu School of Aero-engine and Energy Engineering Shenyang Institute of Aeronautical Engineering Shenyang 110034China School of Energy and Power Engineering Dalian University of Technology Dalian 116024 China

Bifurcation analysis of ignition and extinction of catalytic combustion in a short micro-channel is carded out with the laminar flow model incorporated as the flow model. The square of transverse Thiele modulus and the residence time are used as bifurcation parameters. The influences of different parameters on ignition and extinction behavior are investigated. It is shown that all these parameters have great effects on the bifurcation behaviors of ignition and extinction in the short micro-channel. The effects of flow models on bifurcation behaviors of combustion are also analyzed. The results show that in comparison with the flat velocity profile model, for the case of the laminar flow model, the temperatures of ignition and extinction of combustion are higher and the unsteady multiple solution region is larger.

关键词： catalytic combustion bifurcation theory short monolith

Experimental study on combustion characteristics of Chinese RP-3 kerosene

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Chinese Journal of Aeronautics 2016年第2期29卷 375-385页

作者： Ma Hongan xie maozhao Zeng Wen Chen Baodong School of Energy and Power Engineering Dalian University of Technology Liaoning Key Laboratory of Advanced Test Technology for Aerospace Propulsion System Shenyang Aerospace University

In order to illustrate the combustion characteristics of RP-3 kerosene which is widely used in Chinese aero-engines, the combustion characteristics of RP-3 kerosene were experimentally inves- tigated in a constant volume combustion chamber. The experiments were performed at four different pressures of 0.1 MPa, 0.3 MPa, 0.5 MPa and 0.7 MPa, and three different temperatures of 390 K, 420 K and 450 K, and over the equivalence ratio range of 0.6-1.6. Furthermore, the laminar combus- tion speeds of a surrogate fuel for RP-3 kerosene were simulated under certain conditions. The results show that increasing the initial temperature or decreasing the initial pressure causes an increase in the laminar combustion speed of RP-3 kerosene. With the equivalence ratio increasing from 0.6 to 1.6, the laminar combustion speed increases initially and then decreases gradually. The highest laminar combustion speed is measured under fuel rich condition （the equivalence ratio is 1.2）. At the same time, the Markstein length shows the same changing trend as the laminar com- bustion speed with modification of the initial pressure. Increasing the initial pressure will increase the instability of the flame front, which is established by decreased Markstein length. However, different from the effects of the initial temperature and equivalence ratio on the laminar combustion speed, increasing the equivalence ratio will lead to a decrease in the Markstein length and the stability of the flame front, and the effect of the initial temperature on the Markstein length is unclear. Further- more, the simulated laminar combustion speeds of the surrogate fuel agree with the corresponding experimental datas of RP-3 kerosene within ~10% deviation under certain conditions.

关键词： Combustion mechanism Combustion stability Laminar combustion speed Markstein length RP-3 kerosene

Numerical study on turbulent two-phase flow in porous medium combustion chamber

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Science China(Technological Sciences) 2009年第6期52卷 1511-1520页

作者： DONG Ming xie maozhao LI SuFen School of Energy and Power Engineering Dalian University of TechnologyDalian 116024China

To understand the working mechanism of the porous medium(PM)internal combustion engine,effects of a porous medium heat regenerator inserted into a combustion chamber on the turbulent flow char-acteristics and fuel-air mixture formation are studied by numerical *** cylindrical chamber has a constant volume,in which a disk-shaped PM insert is fixed.A simplified model for the random structure of the PM is presented,in which the PM is represented by an assembly of a great number of randomly distributed solid *** simulate flows in the PM a microscopic approach is employed,in which computations are performed on a pore-scale mesh and based on the standard k-ε turbulence model.A spray model,in which the effects of drop breakup,collision and coalescence are taken into account,is introduced to describe spray/wall *** computations are performed for the turbulent flows induced by a fuel spray outside and inside of the PM with different structure *** results show that the spray/PM interaction has substantial and positive influ-ences on the fuel-air mixture formation and homogenization in the combustion chamber,which could be very advantageous in engine applications.

关键词： porous media turbulence fuel spray numerical simulation spray/PM interaction

Numerical Investigation on Porous Media Quenching Behaviors of Premixed Deflagrating Flame using RANS/LES Model

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Journal of Thermal Science 2019年第4期28卷 780-788页

作者： WEN Xiaoping SU Tengfei LIU Zhigang xie maozhao WANG Fahui LIU Zhichao School of Mechanical and Power Engineering Henan Polytechnic UniversityJiaozuo 454003China Henan Key Laboratory for Green and Efficient Mining & Comprehensive Utilization of Mineral Resources Henan Polytechnic UniversityJiaozuo 454003China The Boiler & Pressure Vessel Safety Inspection Institute of Henan Province Jiaozuo 454000China School of Energy and Power Engineering Dalian University of TechnologyDalian 116024China

To understand the mechanism of premixed flame quenching by porous media,a zonal hybrid RANS/LES model was employed,in which the LES flow solver was used to resolve the large turbulent structures within the non-porous region,while RANS was applied to porous media *** predicted results were compared with previous experimental *** it was evident that the premixed flame propagation rates and structure as well as quenching behaviors were reproduced by this numerical approach with a better *** to the inherently higher heat transfer coefficients between the solid and gas phases in porous media,the gas phase temperature has been decreased ***,upstream obstacles can cause the flame propagating faster and thus reduce the axial gas temperature gradients,resulting in the invalidity of the operation of premixed flame *** comparison with the case without upstream obstacle,the values of reaction rate attained in the case with three pairs of obstacles are higher,which makes a positive impact on the flame passing through the porous *** addition,the porous media with greater pore density has an excellent flame quenching property mainly owing to both the larger volumetric heat transfer and higher quenching temperature.

关键词： RANS/LES model porous media quenching flame propagation

Large eddy simulation and proper orthogonal decomposition analysis of turbulent flows in a direct injection spark ignition engine:Cyclic variation and effect of valve lift

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Science China(Technological Sciences) 2014年第3期57卷 489-504页

作者： QIN WenJin xie maozhao JIA Ming WANG TianYou LIU DaMing School of Energy and Power Engineering Dalian University of Technology State Key Laboratory of Engines Tianjin University

Large eddy simulation(LES)is used to calculate the in-cylinder turbulent flow field in a direct injection spark ignition(DISI)*** computations are carried out for three different maximum valve lifts(MVL)and throughout 100 consecutive engine *** simulated results as well as corresponding particle image velocimetry(PIV)measurement database are analyzed by the proper orthogonal decomposition(POD)*** a new developed POD quadruple decomposition the instantaneous in-cylinder flow fields are decomposed into four parts,named mean field,coherent field,transition field and turbulent field,*** the in-cylinder turbulent flow characteristics and cycle-to-cycle variations(CCV)are studied separately upon the four part flow *** indicate that each part exhibits its specific characteristics and has close connection with *** mean part contains more than 50%of the total kinetic energy and the energy cascade phenomenon occurs among the four part fields;the coherent field part possesses the highest CCV level which dominates CCV of the bulk *** addition,it is observed that a change in MVL affects significantly the in-cylinder flow behavior including CCV,especially for the coherent ***,the POD analysis demonstrates that at least 25 sample cycles for the mean velocity and 50 sample cycles for the RMS velocity are necessary for obtaining converged and correct results in CCV.

关键词： in-cylinder flow turbulence proper orthogonal decomposition(POD) large eddy simulation cycle-to-cycle variations(CCV)

Numerical study of forward smoldering combustionof polyurethane foam

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Journal of Southeast University(English Edition) 2007年第2期23卷 278-284页

作者：贾宝山解茂昭大连理工大学能源与动力学院

A two-dimensional and two-phase numerical model is presented for the smolder propagation in a horizontal polyurethane foam. The chemical processes considered include endothermic pyrolysis and exotherrnic oxidation degradation of polyurethane foam and exothermic oxidation of char. The governing equations are discretized in space using the finite element method and solved by the software package FEMLAB. Predicted profiles of solid temperature as well as evolutions of solid compositions （including foam, char and ash） are presented at an airflow velocity of 0. 28 cm/s. The computed average smoldering velocity is 0. 021 4 cm/s, and the average maximum temperature is 644. 67 K. Based on the evolutions of solid compositions, the packed bed can be obviously divided into four zones： unreacted zone, fuel pyrolysis and oxidation zone, char oxidation zone and fuel burned-out zone. Simultaneously, the effects of inlet air velocity and fuel properties （including thermal conductivity, specific heat, density and pore diameter） are studied on the smoldering propagation. The results show that the smoldering velocity and temperature have a roughly linear increase with increasing inlet air velocity; the fuel density is the most important factor in determining smoldering propagation; radiation has a non-negligible role on the smoldering velocity for larger pore diameters of porous material. The computational results are compared with the experimental data and a general agreement is reached.

关键词： polyurethane foam forward smoldering porous medium smoldering velocity numerical study