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Spatially resolved investigation of flame particle interaction in a two dimensional model packed bed

Particuology 2024年第2期85卷 167-185页

作者： Mohammadhassan Khodsiani Reza Namdar Fathollah Varnik Frank Beyrau Benoit Fond Institute of Fluid Dynamics and Thermodynamics Universitaetsplatz 2Magdeburg39106Saxony-AnhaltGermany Interdisciplinary Centre for Advanced Materials Simulation(ICAMS) Ruhr-University BochumBochum44801Germany onera The french aerospace lab Department of AerodynamicsAeroelasticity and Acoustics(DAAA)Paris-Saclay UniversityMeudon92190France

This study investigates the interaction between a premixed methane-air flame and particles inside a model packed *** opacity of the spherical packed beds to visible light poses a major barrier to the implementation of highly resolved optical diagnostics,so that no detailed experimental data were so far available for the validation of numerical ***,a two-dimensional cylindrical packed bed design is set up,which enables direct line-of-sight optical measurements without loss of spatial reso-lution over the fluid region between the *** this study,the case of cold metallic cylindrical particles(T=377 K)relevant to start-up of a reactor is investigated using internal particle cooling,which also allows cylinder specific heat transfer rate measurements by differential temperature measurements on the coolant *** two dimensional assumption is first verified by measuring the inflow ve-locity and cylinder temperature profile along the *** imaging is then per-formed using a telecentric lens to observe the position and geometry of the two-dimensional flame front with respect to the surrounding cylinders without loss of ***,the cylinder-specific flame to cylinder heat transfer rates and cylinder surface temperature are *** the flame is closely surrounded by the three cooled cylinders,intense heat transfer is observed in this region corresponding to 25±2.5%of the flame thermal *** were stabilised at different positions depending on inflow velocity and equivalence ratio,and a direct correlation between flame to cylinder stand-off distance and the heat transfer rate normalised to the flame thermal power was found for both top and side ***,sidewall quenching distances to the curved cylinder surfaces were evaluated,and seem to be influenced by the presence of a warm recirculation zone behind the *** investigation provides fully resolved flame front position and heat tra

关键词： Packed beds Flame-particle interaction Optical diagnostics Sidewall quenching

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Multi-point temperature measurements in packed beds using phosphor thermometry and ray tracing simulations

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Particuology 2024年第2期85卷 77-88页

作者： Guangtao Xuan Mirko Ebert Simson Julian Rodrigues Nicole Vorhauer-Huget Christian Lessig Benoit Fond Institute of Fluid Dynamics and Thermodynamics OVGU MagdeburgUniversitaetsplatz 2Magdeburg39106Saxony-AnhaltGermany Institute of Simulations and Graphics OVGU MagdeburgUniversitaetsplatz 2Magdeburg39106Saxony-AnhaltGermany Institute of Process Engineering OVGU MagdeburgUniversitaetsplatz 2Magdeburg39106Saxony-AnhaltGermany onera The French Aerospace LabDepartment of AerodynamicsAeroelasticity and Aeroacoustics(DAAA)Paris-Saclay University8rue des VertugadinsMeudon92190France

Packed bed reactors are commonly found in the process industry,for example in flame-assisted calci-nation for cement *** the heat transfer inside the bed is essential for process control,product quality and energy *** we propose a technique to determine the internal temperature distribution of packed beds based on a combination of lifetime-based phosphor ther-mometry,ray tracing simulations,and assimilation of temperature data using finite element heat transfer *** establish and validate the technique,we considered a reproducible regular packing of 6 mm diameter aluminum spheres,with one of the spheres in the top layer being electrically *** a sphere inside the packing is coated with thermographic phosphors and excitation light is directed to-wards the packing,luminescence from the coated sphere exits the packed bed after multiple reflection and the sphere's temperature can be *** measurements showed that the temper-ature obtained by phosphor thermometry is independent of the luminescent sphere *** imaging the luminescence on a camera,the luminescence distribution in recorded image depended,however,on the position of the ***,in setups with multiple phosphor-coated spheres,their signals can be separated using a least squares *** demonstrate the approach using a setup with three luminescent spheres and validated the temperature readings against thermocouple *** obtain the spatial signatures for individual sphere positions required for the least squares fit,ray tracing simulations were *** provide an efficient alternative to single sphere measurements that are only practical for regular spherical packed ***-point measurements were used as input to a finite element heat transfer simulations to determine parameters such as particle-to-particle air gap *** these,the full temperature distribution inside the bed could be assimilated from the meas

关键词： Packed beds Phosphor thermometry Ray tracing Heat transfer simulation Data assimilation

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Numerical study of convective heat transfer in static arrangements of particles with arbitrary shapes:A monolithic hybrid lattice Boltzmann-finite difference-phase field solver

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Particuology 2024年第2期85卷 186-197页

作者： Reza Namdar Mohammadhassan Khodsiani Hesameddin Safari Tanya Neeraj Seyed Ali Hosseini Frank Beyrau Benoit Fond Dominique Thevenin Fathollah Varnik Interdisciplinary Centre for Advanced Materials Simulation(ICAMS) Ruhr-University BochumBochum44801Germany laboratory of Technical Thermodynamics University of Magdeburg"Otto von Guericke"Magdeburg39106Germany laboratory of Fluid Dynamics and Technical Flows University of Magdeburg"Otto von Guericke"MagdeburgD-39106Germany Department of Mechanical and Process Engineering ETH ZurichZurich8092Switzerland onera The french aerospace lab Department of AerodynamicsAeroelasticity and Acoustics(DAAA)Paris-Saclay UniversityMeudon92190France

A compressible lattice Boltzmann-finite difference method is extended by the phase-field approach into a monolithic scheme to study fluid flow and heat transfer through regular arrangements of solid bodies of circular,elliptical and irregular *** advantage of using the phase-field method is demon-strated both in its simplicity of accounting for flow and thermal boundary conditions at solid surfaces with irregular shapes and in the capability of generating such complex-shaped *** an array of discs,numerical results for the overall solid-to-gas heat transfer rate are validated via experiments on flow through arrays of hot *** thus validated compressible LB-FD-PF hybrid scheme is used to study the dependence of heat transfer on flow and thermal boundary conditions(Reynolds number,temperature difference between the hot solid bodies and the inlet gas),porosity as well as on the shape of solid *** are rationalized in terms of the residence time of the gas close to the solid body and downstream variations of gas velocity and *** for further applications of the proposed methodology are also discussed.

关键词： Lattice Boltzmann method Finite difference scheme Convective heat transfer Diffuse interface Thermal compressible flow

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Space truss construction modeling based on on-orbit assembly motion feature

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Chinese Journal of Aeronautics 2024年第3期37卷 365-379页

作者： Changjie ZHAO Weizhong GUO Meng CHEN Jiaxing HU Youcheng HAN Rongfu LIN State Key lab of Mechanical System and Vibration Shanghai Jiao Tong UniversityShanghai 200240China Institute of aerospace System Engineering Shanghai Shanghai 201109China

More space truss construction has been planned to develop and utilize space *** trusses are designed in the way of large-scale,complex,modular,and on-orbit *** meet the upcoming challenge of large-scale space infrastructure construction,it is necessary to study space truss automation design and robotic *** paper proposes an ordinal finite screw adjacency matrix model(OFSAMM),focusing on the relationship between assembly motions,to express and compute a space truss *** this model,a space truss is abstracted as a set of ordered assembly motions,each of which is recorded as a finite screw as the basic element of the truss and its *** operation of truss transformation is also derived under this ***,the truss configuration,the assembly sequence,the truss sub-assembly,the truss components,and the on-orbit assembly task can be expressed and calculated in a unified model,which is calculated and stores the truss topology and assembly with the minimum storage *** the end of this paper,we introduce how to synthesize and optimize space truss design through two *** study will help to improve design ***,it provides a theoretical basis for the automatic construction of space truss structures,especially in the next stage.

关键词： Adjacency matrix Finite screw On-orbit construction modeling Space applications Space trusses Topology design

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Impact Force Localization and Reconstruction via ADMM-based Sparse Regularization Method

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Chinese Journal of Mechanical Engineering 2024年第3期37卷 170-188页

作者： Yanan Wang Lin Chen Junjiang Liu Baijie Qiao Weifeng He Xuefeng Chen National Key lab of aerospace Power System and Plasma Technology Xi’an Jiaotong UniversityXi’an 710049China School of Mechanical Engineering Xi’an Jiaotong UniversityXi’an 710049China

In practice,simultaneous impact localization and time history reconstruction can hardly be achieved,due to the illposed and under-determined problems induced by the constrained and harsh measuring *** l_(1) regularization can be used to obtain sparse solutions,it tends to underestimate solution amplitudes as a biased *** address this issue,a novel impact force identification method with l_(p) regularization is proposed in this paper,using the alternating direction method of multipliers(ADMM).By decomposing the complex primal problem into sub-problems solvable in parallel via proximal operators,ADMM can address the challenge *** mitigate the sensitivity to regularization parameters,an adaptive regularization parameter is derived based on the K-sparsity ***,an ADMM-based sparse regularization method is developed,which is capable of handlingl_(p) regularization with arbitrary p values using adaptively-updated *** effectiveness and performance of the proposed method are validated on an aircraft skin-like composite ***,an investigation into the optimal p value for achieving high-accuracy solutions vial_(p) regularization is *** turns out that?_(0.6)regularization consistently yields sparser and more accurate solutions for impact force identification compared to the classicl_(1) regularization *** impact force identification method proposed in this paper can simultaneously reconstruct impact time history with high accuracy and accurately localize the impact using an under-determined sensor configuration.

关键词： Impact force identification Non-convex sparse regularization Alternating direction method of multipliers Proximal operators

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Airfoil friction drag reduction based on grid-type and super-dense array plasma actuators

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Plasma Science and Technology 2024年第2期26卷 94-103页

作者：方子淇宗豪华吴云梁华苏志 School of aerospace Engineering Xi'an Jiaotong UniversityXi'an 710049People's Republic of China School of Mechanical Engineering Xi'an Jiaotong UniversityXi'an 710049People's Republic of China National Key lab of aerospace Power System and Plasma Technology Air Force Engineering UniversityXi'an 710038People's Republic of China

To improve the cruise flight performance of aircraft, two new configurations of plasma actuators(grid-type and super-dense array) were investigated to reduce the turbulent skin friction drag of a low-speed airfoil. The induced jet characteristics of the two actuators in quiescent air were diagnosed with high-speed particle image velocimetry(PIV), and their drag reduction efficiencies were examined under different operating conditions in a wind tunnel. The results showed that the grid-type plasma actuator was capable of producing a wall-normal jet array(peak magnitude: 1.07 m/s) similar to that generated in a micro-blowing technique, while the superdense array plasma actuator created a wavy wall-parallel jet(magnitude: 0.94 m/s) due to the discrete spanwise electrostatic forces. Under a comparable electrical power consumption level,the super-dense array plasma actuator array significantly outperformed the grid-type configuration,reducing the total airfoil friction drag by approximately 22% at a free-stream velocity of 20 m/*** magnitude of drag reduction was proportional to the dimensionless jet velocity ratio(r), and a threshold r = 0.014 existed under which little impact on airfoil drag could be discerned.

关键词： plasma actuator flow control drag reduction airfoil

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Numerical simulation of liquid sloshing in a spherical tank by MPS method

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Journal of Hydrodynamics 2024年第2期36卷 232-240页

作者： Cong-yi Huang Ji-fei Wang Wei-wen Zhao De-cheng Wan Computational Marine Hydrodynamic lab(CMHL) School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai200240China Shanghai aerospace System Engineering Institute Shanghai201109China

This paper investigates the sloshing phenomena in a spherical liquid tank using the moving particle semi-implicit(MPS)method,a crucial study in fluid *** from previous research focused on rectangular or LNG tanks,this work explores the unique motion patterns inherent to spherical *** accuracy of our in-house MPS solver MLParticle-SJTU is validated against experimental data and finite volume method(FVM).And the MPS method reveals a closer alignment with experimental outcomes,which suggests that MPS method is particularly effective for modeling complex,non-linear fluid *** the fluid’s response to excitation at its natural frequency is simulated,showcasing vigorous sloshing and rotational *** analyses of the fluid motion are conducted by drawing streamline diagrams,velocity vector diagrams,and vorticity *** fluid’s motion response is explored using both time-domain and frequency-domain curves of the fluid centroid,as well as the sloshing force.

关键词： Moving particle semi-implicit(MPS)method spherical tank liquid sloshing model experiment

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Rotor cross-tilt optimization for yaw control improvement of multi-rotor eVTOL aircraft

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Chinese Journal of Aeronautics 2024年第3期37卷 153-167页

作者： Xufei YAN Ye YUAN Yanqin ZHAO Renliang CHEN Zhejiang lab Hangzhou 311100China Department of aerospace Engineering Swansea UniversitySwanseaWales SA28PPUK National Key laboratory of Rotorcraft Aeromechanics Nanjing University of Aeronautics and AstronauticsNanjing 210016China

Manned multi-rotor electric Vertical Takeoff and Landing(eVTOL)aircraft is prone to actuator saturation due to its weak yaw control *** address this inherent problem,a rotor cross-tilt configuration is applied in this paper,with an optimization method proposed to improve the overall control efficiency of the ***,a flight dynamics model of a 500-kg manned multi-rotor eVTOL aircraft is *** accuracy of the co-axial rotor model is verified using a single arm test bench,and the accuracy of the flight dynamics model is verified by the flight test ***,an optimization method is designed based on the flight dynamics model to calculate an optimal rotor cross-tilt mounting angle,which not only improves the yaw control efficiency,but also basically maintains the efficiency of other control *** ideal rotor cross-tilt mounting angle for the prototype is determined by comprehensively considering the optimal results with different payloads,forward flight speeds,and rotor mounting angle ***,the feasibility of the rotor cross-tilt mounting angle is proved by analyzing the control derivatives of the flight dynamics model,the test data of a ground three Degree-of-Freedom(3DOF)platform,and the actual flight data of the *** results show that a fixed rotor cross-tilt mounting angle can achieve ideal yaw control effectiveness,improving yaw angle tracking and hold ability,increasing endurance time,and achieving good yaw control performance with different payloads and forward speeds.

关键词： Multi-rotor eVTOL Control efficiency Flight dynamics model Cross-tilt optimization Endurance time

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Improving flight performance of UAVs by ice shape modulation

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Chinese Journal of Aeronautics 2024年第8期37卷 49-62页

作者： Jiajun ZHANG Xuecheng LIU Hua LIANG Like XIE Biao WEI Haohua ZONG Yun WU Yinghong Li National Key lab of aerospace Power System and Plasma Technology Air Force Engineering UniversityXi’an 710038China Institute of Aero-Engine School of Mechanical EngineeringXi’an Jiaotong UniversityXi’an 710049China

Aircraft icing poses a great threat to flight *** response to the characteristics of high-power consumption,large volume,and heavy weight of traditional anti-/de-icing technologies,the concept of ice shape modulation is proposed,which is called ice tolerant ***,the flight performance of Unmanned Aerial Vehicle(UAV)was compared in three states:no ice,full ice,and modulated ice through flight *** was found that ice shape modulation has a significant improvement effect on the aerodynamic performance of aircraft under icing *** the three modulated ice shape conditions in this experiment,the lift coefficient of the UAV under different ice shape modulation conditions increased by 18%–33%,and the stalling angle was delayed by 3°-5°.Subsequently,the pressure distribution,streamlines in the flow field,and detached vortex distribution of the UAV model in these three states were obtained through numerical simulation,to study the mechanism of ice shape modulation on the aerodynamic performance of *** simulation found that the reason for the improvement of the wings effect after ice shape modulation is that the modulated area forms a leading-edge protrusion structure similar to a vortex *** structure prolongs the mixed flow region on the wings surface and reduces the trend of flow separation,which plays a role in increasing lift and reducing drag for UAVs under icing ***,a reverse reachable set that can be used for unexpected state recovery is used as the definition of flight safety boundaries,and an aircraft dynamics model is established to obtain flight safety boundaries for different *** has found that the flight safety boundary of the UAV in a no ice state is greater than that in a modulated ice state,and the safety boundary in a modulated ice state is greater than that in a full ice *** with the full ice state,the flight safety boundary after modulation has expanded by 27.0%.The sch

关键词： Ice shape modulation Aerodynamic performance Reachable set Flight safety UAV

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Combination of classifiers with incomplete frames of discernment

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Chinese Journal of Aeronautics 2022年第5期35卷 145-157页

作者： Zhunga LIU Jingfei DUAN Linqing HUANG Jean DEZERT Yongqiang ZHAO School of Automation Northwestern Polytechnical UniversityXi’an 710072China onera–the french aerospace lab Palaiseau 91761France

The methods for combining multiple classifiers based on belief functions require to work with a common and complete(closed)Frame of Discernment(Fo D)on which the belief functions are defined before making their *** theoretical requirement is however difficult to satisfy in practice because some abnormal(or unknown)objects that do not belong to any predefined class of the Fo D can appear in real classification *** classifiers learnt using different attributes information can provide complementary knowledge which is very useful for making the classification but they are usually based on different Fo *** order to clearly identify the specific class of the abnormal objects,we propose a new method for combination of classifiers working with incomplete frames of discernment,named CCIF for *** is a progressive detection method that select and add the detected abnormal objects to the training data *** one pattern can be considered as an abnormal object by one classifier and be committed to a specific class by another one,a weighted evidence combination method is proposed to fuse the classification results of multiple *** new method offers the advantage to make a refined classification of abnormal objects,and to improve the classification accuracy thanks to the complementarity of the *** experimental results are given to validate the effectiveness of the proposed method using real data sets.

关键词： Abnormal object Belief functions Classifier fusion Evidence theory Detection

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