We present an Euler-Lagrange method for the simulation of wood gasification in a bubbling fluidized bed. The gas phase is modeled as a continuum using the 2D Navier-Stokes equations and the solid phase is modeled by a...We present an Euler-Lagrange method for the simulation of wood gasification in a bubbling fluidized bed. The gas phase is modeled as a continuum using the 2D Navier-Stokes equations and the solid phase is modeled by a Discrete Element Method （DEM） using a soft-sphere approach for the particle collision dynamic. Turbulence is included via a Large-Eddy approach using the Smagorinsky sub-grid model. The model takes into account detailed gas phase chemistry, zero-dimensional modeling of the pyrolysis and gasification of each individual particle, particle shrinkage, and heat and mass transfer between the gas phase and the particulate phase. We investigate the influence of wood feeding rate and compare exhaust gas compositions and temperature results obtained with the model against experimental data of a laboratory scale bubbling fiuidized bed reactor.展开更多
The present research on moulded case circuit breaker（MCCB） focuses on the enhancement of current-limiting interrupting performance during short circuit, overload, under voltage and phase failure, involving electrics...The present research on moulded case circuit breaker（MCCB） focuses on the enhancement of current-limiting interrupting performance during short circuit, overload, under voltage and phase failure, involving electrics, magnetic, mechanics, thermal, material, friction, arc extinguishing, impact vibration, skin effect, etc. The rigid-flexible coupling of the parts and components of the metamorphic manipulating mechanism in multi-fields leads to the non-rigid, high frequency, high damping, singularity of the Euler-Lagrange equations which represents the multi-body dynamics. The small step iteration which is used for obtaining the instantaneous and short time critical interrupting performance of metamorphic mechanism appears inaccuracy. It is difficult to realize top-down design by existing CAD systems. Therefore, a metamorphic manipulating mechanism design method for MCCB using index reduced iteration（IRI） is put forward. The metamorphic manipulating mechanism of MCCB is decomposed into three mechanisms： main switch connector mechanism, electromagnet-drawbar-jump buckle mechanism, and bimetallic strip-drawbar mechanism, which is respectively described by electro-dynamic force, electromagnet force, and bimetallic strip force. The dummy part（virtual rigid） without moment of inertia and mass is employed as intermediate to join the flexible body and rigid body. The model of rigid-flexible coupling metamorphic mechanism multi-body dynamics is built. The differential algebraic equations（DAEs） of the multibody dynamics model are converted to pure ordinary differential equations（ODEs） by coordinate partition. Order reduced integration with multi-step and variable step-size is preceded based on IRI. The non-linear algebraic equations are solved in each integration step by Newton-Rapson iteration. There is no ill-condition and singularity of Jacobian matrix when step size reduces to zero. The independent prototype design system using ACIS R13, HOOPS V11.0 and Visual C＋＋.NET 2003 has been developed, whi展开更多
A transient three-dimensional（3 D） model was established to understand the bubble motion in an industrial electrolytic process. An anode with a new design was tested. It incorporates two slots that allow an efficien...A transient three-dimensional（3 D） model was established to understand the bubble motion in an industrial electrolytic process. An anode with a new design was tested. It incorporates two slots that allow an efficient removal of gas bubbles. The electromagnetic fields were described by solving Maxwell＇s equations. The bubble movement was studied with two-way coupling Euler-Lagrange approach. The interplay of current density and bubble nucleation rate was included. The collision and coalescence of bubbles were considered. Random walk module was invoked for involving the chaotic effect of the turbulence. The numerical results were validated by experimental measurements. The results indicate that the current distribution and the bubble nucleation periodically change. Due to the slot, the bubble elimination heavily increases. The contribution of the slot to the bubble removal exceeds 50% in the case of three currents, and the promotion of the slot decays with increasing the current.展开更多
Ultra-fine grained TA5 titanium alloy was fabricated by friction stir processing(FSP).Temperature distribution and material flow were simulated by the coupled Euler−Lagrange(CEL)method.The microstructure and mechanica...Ultra-fine grained TA5 titanium alloy was fabricated by friction stir processing(FSP).Temperature distribution and material flow were simulated by the coupled Euler−Lagrange(CEL)method.The microstructure and mechanical properties of TA5 alloy were characterized by optical and scanning electron microscope,Vickers hardness,and tensile tests.The processed alloy was composed of ultra-fine grained and equiaxed grains due to dynamic recrystallization.The microstructure recrystallized through grain boundary rotation and dislocation accumulation.The grain size reached the minimum on the advancing side of the stir zone with the highest grain misorientation.Ultimate tensile strength was promoted to over 830 MPa after FSP at a rotating speed of 200 r/min,whereas elongation varied a little.The specimens all fractured on the retreating side of the stir zone and smaller dimples were depicted from the fracture morphologies of FSP specimens.展开更多
Euler-Lagrange coupling method is used to establish the fluid-structure interaction model for tires with different tread patterns by obtaining the grounding mark and normal contact force between tire and the road surf...Euler-Lagrange coupling method is used to establish the fluid-structure interaction model for tires with different tread patterns by obtaining the grounding mark and normal contact force between tire and the road surface during tire rolling.The altering of load force,tire pressure,and water film thickness in relation to the effect on tire-road force during both constant speed and critical hydroplaning speed was analyzed.Results show that the critical hydroplaning speed and normal contact force between tire and the road surface are positively correlated with vehicle load and tire pressure and negatively correlated with water film thickness.Python language is used to develop the pre-processing plug-ins to achieve parametric modeling and rapid creation of Finite Element Analysis(FEA)model to reduce time costs,and the effectiveness of the plug-ins is verified through comparative tests.展开更多
文摘We present an Euler-Lagrange method for the simulation of wood gasification in a bubbling fluidized bed. The gas phase is modeled as a continuum using the 2D Navier-Stokes equations and the solid phase is modeled by a Discrete Element Method （DEM） using a soft-sphere approach for the particle collision dynamic. Turbulence is included via a Large-Eddy approach using the Smagorinsky sub-grid model. The model takes into account detailed gas phase chemistry, zero-dimensional modeling of the pyrolysis and gasification of each individual particle, particle shrinkage, and heat and mass transfer between the gas phase and the particulate phase. We investigate the influence of wood feeding rate and compare exhaust gas compositions and temperature results obtained with the model against experimental data of a laboratory scale bubbling fiuidized bed reactor.
基金supported by National Basic Research Program of China(973 Program, Grant No. 2011CB706506)National S&T Great Special of China(Grant Nos. 2012ZX04010011, 2011ZX04014-131)+1 种基金National Science Foundation for Young Scholars of China(Grant No. 51005204)Postdoctoral Fund of China(Grant No. 20100471000)
文摘The present research on moulded case circuit breaker（MCCB） focuses on the enhancement of current-limiting interrupting performance during short circuit, overload, under voltage and phase failure, involving electrics, magnetic, mechanics, thermal, material, friction, arc extinguishing, impact vibration, skin effect, etc. The rigid-flexible coupling of the parts and components of the metamorphic manipulating mechanism in multi-fields leads to the non-rigid, high frequency, high damping, singularity of the Euler-Lagrange equations which represents the multi-body dynamics. The small step iteration which is used for obtaining the instantaneous and short time critical interrupting performance of metamorphic mechanism appears inaccuracy. It is difficult to realize top-down design by existing CAD systems. Therefore, a metamorphic manipulating mechanism design method for MCCB using index reduced iteration（IRI） is put forward. The metamorphic manipulating mechanism of MCCB is decomposed into three mechanisms： main switch connector mechanism, electromagnet-drawbar-jump buckle mechanism, and bimetallic strip-drawbar mechanism, which is respectively described by electro-dynamic force, electromagnet force, and bimetallic strip force. The dummy part（virtual rigid） without moment of inertia and mass is employed as intermediate to join the flexible body and rigid body. The model of rigid-flexible coupling metamorphic mechanism multi-body dynamics is built. The differential algebraic equations（DAEs） of the multibody dynamics model are converted to pure ordinary differential equations（ODEs） by coordinate partition. Order reduced integration with multi-step and variable step-size is preceded based on IRI. The non-linear algebraic equations are solved in each integration step by Newton-Rapson iteration. There is no ill-condition and singularity of Jacobian matrix when step size reduces to zero. The independent prototype design system using ACIS R13, HOOPS V11.0 and Visual C＋＋.NET 2003 has been developed, whi
基金Project(51434005) supported by the National Natural Science Foundation of China
文摘A transient three-dimensional（3 D） model was established to understand the bubble motion in an industrial electrolytic process. An anode with a new design was tested. It incorporates two slots that allow an efficient removal of gas bubbles. The electromagnetic fields were described by solving Maxwell＇s equations. The bubble movement was studied with two-way coupling Euler-Lagrange approach. The interplay of current density and bubble nucleation rate was included. The collision and coalescence of bubbles were considered. Random walk module was invoked for involving the chaotic effect of the turbulence. The numerical results were validated by experimental measurements. The results indicate that the current distribution and the bubble nucleation periodically change. Due to the slot, the bubble elimination heavily increases. The contribution of the slot to the bubble removal exceeds 50% in the case of three currents, and the promotion of the slot decays with increasing the current.
基金The authors are grateful for the financial support from the National Natural Science Foundation of China(51974100).
文摘Ultra-fine grained TA5 titanium alloy was fabricated by friction stir processing(FSP).Temperature distribution and material flow were simulated by the coupled Euler−Lagrange(CEL)method.The microstructure and mechanical properties of TA5 alloy were characterized by optical and scanning electron microscope,Vickers hardness,and tensile tests.The processed alloy was composed of ultra-fine grained and equiaxed grains due to dynamic recrystallization.The microstructure recrystallized through grain boundary rotation and dislocation accumulation.The grain size reached the minimum on the advancing side of the stir zone with the highest grain misorientation.Ultimate tensile strength was promoted to over 830 MPa after FSP at a rotating speed of 200 r/min,whereas elongation varied a little.The specimens all fractured on the retreating side of the stir zone and smaller dimples were depicted from the fracture morphologies of FSP specimens.
基金the Major Special Programs of Science and Technology in Tongling City(No.20200101005).
文摘Euler-Lagrange coupling method is used to establish the fluid-structure interaction model for tires with different tread patterns by obtaining the grounding mark and normal contact force between tire and the road surface during tire rolling.The altering of load force,tire pressure,and water film thickness in relation to the effect on tire-road force during both constant speed and critical hydroplaning speed was analyzed.Results show that the critical hydroplaning speed and normal contact force between tire and the road surface are positively correlated with vehicle load and tire pressure and negatively correlated with water film thickness.Python language is used to develop the pre-processing plug-ins to achieve parametric modeling and rapid creation of Finite Element Analysis(FEA)model to reduce time costs,and the effectiveness of the plug-ins is verified through comparative tests.
