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Stability characteristics and airworthiness requirements of blended wing body aircraft with podded engines

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Chinese journal of Aeronautics 2022年第6期35卷 77-86页

作者： Lixin WANG Ning zHANG Hailiang liu Ting YUE School of Aeronautics Science and Engineering Beihang UniversityBeijing 100083China

Blended-Wing-Body(BWB)aircraft have a relatively short fuselage and no horizontal tail,and they usually adopt podded engines and a V tail instead of a vertical ***,BWB aircraft have decreased longitudinal and directional static stability and *** this paper,the three-axis static and dynamic stability characteristics of an example BWB aircraft with podded engines are *** to the differences in flight characteristics of BWB aircraft and conventional aircraft,the different airworthiness requirements for BWB aircraft are analyzed:first,based on current airworthiness regulations and transport aircraft flying quality specification,the relaxation requirement of longitudinal static stability for BWB aircraft is studied;second,the influences of podded engines on longitudinal trim,attitude and trajectory responses and maximum directional control power requirement of BWB aircraft are analyzed;third,the changes in the proportional relationships between the takeoff characteristic speeds of the example BWB aircraft are *** view of these variations in directional control power requirement and relationships between takeoff characteristic speeds,new recommendations for airworthiness evaluation are proposed for BWB *** conclusions of this paper are helpful references for configuration design,flight control law design and airworthiness evaluation of BWB aircraft.

关键词： Airworthiness Blended wing body Podded engine Relaxed static stability Stability characteristics

Principal coordinates and principal velocity gradient tensor decomposition

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journal of Hydrodynamics 2020年第3期32卷 441-453页

作者： Yifei Yu Pushpa Shrestha Charles Nottage Chaoqun liu Department of Mathematics University of Texas at ArlingtonArlington 76019USA

Helmholtz velocity decomposition and Cauchy-Stokes tensor decomposition have been widely accepted as the foundation of fluid kinematics for a long ***,there are some problems with these decompositions which cannot be ***,Cauchy-Stokes decomposition itself is not Galilean invariant which means under different coordinates,the stretching(compression)and deformation are quite *** problem is that the anti-symmetric part of the velocity gradient tensor is not the proper quantity to represent fluid *** show these two drawbacks,two counterexamples are given in this ***“principal coordinate”and“principal decomposition”are introduced to solve the problems of Helmholtz *** easy way is given to find the Principal decomposition which has the property of Galilean invariance.

关键词： Velocity decomposition Helmholtz Cauchy-Stokes liutex principal coordinate

Assessment and improvement of k-ω-γ model for separation-induced transition prediction

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Chinese journal of Aeronautics 2022年第11期35卷 219-234页

作者： Yatian zHAO jianqiang CHEN Rui zHAO Hongkang liu School of Aeronautics and Astronautics Central South UniversityChangsha 41083China State Key Laboratory of Aerodynamics China Aerodynamics Research and Development CenterMianyang 621000China Computational Aerodynamics Institute China Aerodynamics Research and Development CenterMianyang 621000China School of Aerospace Engineering Bejing Institute of TechnologyBeijing 100081China Key Laboratory of Traffic Safety on Track of Ministry of Education School of Traffic&Transportation EngineeringCentral South UniversityChangsha 410075China

The purpose of this work is to improve the k-ω-γtransition model for separationinduced transition *** fundamental cause of the excessively small separation bubble predicted by k-ω-γmodel is scrutinized from the perspective of model *** the basis,three rectifications are conducted to improve the k-ω-γmodel for separation-induced ***,a damping function is established via comparing the molecular diffusion timescale with the rapid pressure-strain *** damping function is applied to prevent the effective length scale from incorrect distribution near the leading edge of the separation ***,the pressure gradient parameterλζ,is proposed as an indicator for local susceptibility to the separation ***,λζ,-based separation intermittencyγsep is constructed to accelerate the substantial growth of turbulent kinetic energy after flow *** improved model appropriate for both low-and high-speed flow has been calibrated against a variety of diverse and challenging experiments,including the subsonic T3L plate,Aerospatial A airfoil,transonic NLR-7301 airfoil and deformed hypersonic inflatable aerodynamic decelerator *** improved model is strictly based on local variables and Galilean ***,the proposed improvement for k-ω-γmodel can be fairly convenient to incorporate into other existing intermittency-based transition models.

关键词： Boundary layer transition Intermittency Local variables Separation bubble Transition model

Numerical analysis on propulsive efficiency and pre-deformated optimization of a composite marine propeller

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Science China(Technological Sciences) 2020年第12期63卷 2562-2574页

作者： zHANG jing WU Qin WANG GuoYu liu TaoTao School of Mechanical Engineering Beijing Institute of TechnologyBeijing 100081China

The objectives of this paper are to numerically investigate the performance of a composite propeller through bidirectional FSI algorithm combining CFD and FEM,and to improve its propulsive efficiency by a pre-deformated method. Numerical results are presented for the composite propeller which has been modeled by unidirectionally stacking with glass-fiber reinforced composites. The propulsive efficiency of the composite and rigid propellers with different advance coefficients j has been *** results show that the efficiency of the composite propeller is obviously higher than that of the rigid propeller when j≤0.8,which is attributed to the decrease of pitch angle caused by the bend-twist coupling effects. But for the design condition j=0.851 and the cases with j>0.851,the efficiency of the composite propeller is significantly lower than that of the rigid propeller,which is because the angle of attack αcomposite is deviated from the optimal angle of attack αdesign more than that for the rigid case α*** on the optimization by the proposed pre-deformated method,the efficiency improvement of the composite propeller at the conditions with j≥0.851 could be obtained,and the composite material used in this work can meet the strength requirement of the designed propellers.

关键词： marine propeller computational fluid dynamic(CFD) propulsive efficiency pre-deformated optimization fluid-structure interaction(FSI)

A modified active disturbance rejection control for a wastewater treatment process

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Chinese journal of Chemical Engineering 2020年第10期28卷 2607-2619页

作者： Wei Wei Pengfei Xia zaiwen liu Min zuo Beijing Technology and Business University Beijing 100048China National Engineering Laboratory for Agri-product Quality TraceabilityBeijing Technology and Business UniversityBeijing 100048China Beijing Key Laboratory of Big Data Technology for Food SafetyBeijing 100048China

Waste water treatment process(WWTP)control has been attracting more and more ***,various undesired factors,such as disturbance,uncertainties,and strong nonlinear couplings,propose big challenges to the control of a *** order to improve the control performance of the closed-loop system and guarantee the discharge requirements of the effluent quality,rather than take the model dependent control approaches,an active disturbance rejection control(ADRC)is *** on the control signal and system output,a phase optimized ADRC(POADRC)is designed to control the dissolved oxygen and nitrate concentration in a *** phase advantage of the phase optimized extended state observer(POESO),convergence of the POESO,and stability of the closed-loop system are analyzed from the theoretical point of ***,a commonly accepted benchmark simulation model no.1.(BSM1)is utilized to test the POESO and *** active disturbance rejection control(LADRC)and the suggested proportion-integration(PI)control are taken to make a comparative *** system responses and performance index values confirm the advantage of the POADRC over the LADRC and the suggested PI *** results show that,as a result of the leading phase of the total disturbance estimation,the POESO based POADRC is an effective and promising way to control the dissolved oxygen and nitrate concentration so as to ensure the effluent quality of a WWTP.

关键词： Wastewater treatment process BSM1 Dissolved oxygen Nitrate concentration Active disturbance rejection control Phase optimization extended state observer

Role of glycine on sulfuric acid-ammonia clusters formation:Transporter or participator

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journal of Environmental Sciences 2020年第3期32卷 125-135页

作者： Danfeng Li Dongping Chen Fengyi liu Wenliang Wang Key Laboratory for Macromolecular Science of Shaanxi Province School of Chemistry and Chemical EngineeringShaanxi Normal UniversityXi’an 710119China

Glycine(Gly) is ubiquitous in the atmosphere and plays a vital role in new particle formation(NPF).However,the potential mechanism of its on sulfuric acid(SA)-ammonia(A)clusters formation under various atmospheric conditions is still ***,a(Gly)x·(SA)y·(A)z(z≤x+y≤3) multicomponent system was investigated by using density functional theory(DFT) combined with Atmospheric Cluster Dynamics Code(ACDC) at different temperatures and precursor *** results show that Gly,with one carboxyl(-COOH) and one amine(-NH2) group,can interact strongly with SA and A in two directions through hydrogen bonds or proton *** the relevant range of atmospheric concentrations,Gly can enhance the formation rate of SA-A-based clusters,especially at low temperature,low [SA],and median [A].The enhancement(R) of Gly on NPF can be up to 340 at T=218.15 K,[SA]=10^4,[A]=10^9,and [Gly]=107 molecules/cm^*** addition,the main growth paths of clusters show that Gly molecules participate into cluster formation in the initial stage and eventually leave the cluster by evaporation in subsequent cluster growth at low [Gly],it acts as an important "transporter" to connect the smaller and larger *** the increase of [Gly],it acts as a "participator" directly participating in NPF.

关键词： New particle formation(NPF) Glycine Atmospheric cluster Atmospheric cluster dynamics code Enhancement mechanism

Electronic properties and photodegradation ability of Nd-TiO_(2)for phenol

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journal of Rare Earths 2022年第7期40卷 1063-1072页

作者： zhimin zhao jinjia liu Gala Sa Aiju Xu Inner Mongolia Key Laboratory of Green Catalysis College of Chemistry and Environmental ScienceInner Mongolia Normal UniversityHohhot 010022China State Key Laboratory of Coal Conversion Institute of Coal Chemistry Chinese Academy of SciencesTaiyuan 030001China National Energy Center for Coal to Clean Fuels Synfuels China Co.Ltd.Beijing 101400China

In this study,the photocatalytic activity of Nd-TiO_(2)photocatalysts obtained by common hydrothermal method was evaluated by practical experiments and theoretical calculations based on density functional theory(DFT).The synthesized photocatalysts were characterized by X-ray diffraction(XRD),N_(2)adsorption-desorption,Fourier transform infrared spectroscopy(FT-IR),high resolution transmission electron microscopy(HRTEM),X-ray photoelectron spectroscopy(XPS),UV-Vis diffuse reflectance spectroscopy(DRS),and photoluminescence(PL)to study their physical/chemical prope *** the same time,the photoelectronic performance was also *** photodegradation ability of asprepared photocatalysts and the effect of Nd doped amount and photocatalysts dosage were investigated by the photodegradation of phenol(30 mg/L)under 400 W metal halide lamp(UV-Vis).The effect of Nd on electronic properties of TiO_(2)and adsorption ability of phenol were *** show the red-shift wavelength of 0.5 mol%Nd-TiO_(2),indicating that its absorption capacity is stronger than pristine TiO_(2)in the same wavelength *** result of DFT calculations demonstrates that the optical bandgap of Nd-TiO_(2)is profoundly reduced,thus the light absorption ability is promoted,which will be responsible for the enhanced photocatalytic performance of Nd-TiO_(2).0.5 mol%Nd is an optimum value for photodegradation phenol,and phenol can be completely degraded by 0.5 mol%Nd-TiO_(2)for 210 min,the higher catalytic performance is derived from the efficient separation of e-/h+***,the adsorption energy calculations of phenol on TiO_(2)(101)and Nd-TiO_(2)(101)demonstrate that the Nd doping can significantly enhance the adsorption ability of phenol on catalyst surfaces because of the formation of Nd-O *** last,the stability measurement through four recycles exhibits that 0.5 mol%Nd-TiO_(2)possesses excellent stability.

关键词： TiO_(2) Hydrothermal method Density functional theory Phenol Photodegradation Rare earths

Indirect approach for predicting cutting force coefficients and power consumption in milling process

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Advances in Manufacturing 2022年第1期10卷 101-113页

作者： Kai-Ning Shi Ning liu Cong-Le liu jun-Xue Ren Shan-Shan Yang Wei Chit Tan Key Laboratory of High Performance Manufacturing for Aero Engine Department of Mechanical EngineeringMinistry of Industry and Information TechnologyNorthwestern Polytechnical UniversityXi’an 710072People’s Republic of China Engineering Research Centre of Advanced Manufacturing Technology for Aero Engine Department of Mechanical EngineeringMinistry of EducationNorthwestern Polytechnical UniversityXi’an 710072People’s Republic of China Virtual Manufacturing Group Smart Manufacturing DivisionAdvanced Remanufacturing and Technology Centre3 Cleantech Loop#01-01CleanTech TwoSingapore 637143Singapore

Accurate energy consumption modeling is an essential prerequisite for sustainable ***,cutting-power-based models have garnered significant attention,as they can provide more comprehensive information regarding the machining energy consumption ***,their implementation is challenging because new cutting force coefficients are typically required to address new workpiece ***,cutting force coefficients are calculated at a high operation cost as a dynamometer must be ***,a novel indirect approach for estimating the cutting force coefficients of a new tool-workpiece pair is proposed *** key idea is to convert the cutting force coefficient calculation problem into an optimization problem,whose solution can be effectively obtained using the proposed simulated annealing ***,the cutting force coefficients for a new tool-workpiece pair can be estimated from a pre-calibrated energy consumption *** experiments performed using different machine tools clearly demonstrate the effectiveness of the developed *** studies with measured cutting force coefficients reveal the decent accuracy of the approach in terms of both energy consumption prediction and instantaneous cutting force *** proposed approach can provide an accurate and reliable estimation of cutting force coefficients for new workpiece materials while avoiding operational or economic problems encountered in traditional force monitoring methods involving ***,this study may significantly advance the development of sustainable manufacturing.

关键词： Sustainable manufacturing Cutting force coefficients Energy consumption Machining processSimulated annealing

Optimization of fixed aviation support resource station configuration for aircraft carrier based on aircraft dispatch mission scheduling

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Chinese journal of Aeronautics 2023年第2期36卷 127-138页

作者： Yujie liu Wei HAN Xichao SU Rongwei CUI Aeronautical Foundation College Naval Aviation UniversityYantai 264001China Aeronautical Operations College Naval Aviation UniversityYantai 264001China

Before the dispatch of the carrier-based aircraft,a series of pre-flight preparation operations need to be completed on the flight *** deck fixed aviation support resource station configuration has an important impact on operation efficiency and sortie ***,the resource station configuration is determined during the aircraft carrier design phase and is rarely modified as required,which may not be suitable for some pre-flight preparation *** order to solve the above defects,the joint optimization of flight deck resource station configuration and aircraft carrier pre-flight preparation scheduling is studied in this paper,which is formulated as a two-tier optimization decision-making *** improved variable neighborhood search algorithm with four original neighborhood structures is *** mission experiment and algorithm performance comparison experiment are carried out in the computational experiment *** correlation between the pre-flight preparation time(makespan)and flight deck cabin occupancy percentage is given,and advantages of the proposed algorithm in solving the mathematical model are verified.

关键词： Carrier-based aircraft Multi-objective optimization Resource configuration Scheduling Variable neighborhood search