检索结果-南通市图书馆

Supervised learning with probability interpretation in airfoil transition judgment

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2023年第1期36卷 91-104页

作者： Binbin WEI yongwei gao Dong LI Lei DENG School of Aeronautics Northwestern Polytechnical UniversityXi’an 710072China

Transition prediction has always been a frontier issue in the field of aerodynamics.A supervised learning model with probability interpretation for transition judgment based on experimental data was developed in this *** solved the shortcomings of the point detection method in the experiment,that which was often only one transition point could be obtained,and comparison of multi-point data was ***,the Variable-Interval Time Average(VITA)method was used to transform the fluctuating pressure signal measured on the airfoil surface into a sequence of states which was described by Markov chain ***,a feature vector consisting of one-step transition matrix and its stationary distribution was ***,the Hidden Markov Model(HMM)was used to pre-classify the feature vectors marked using the traditional Root Mean Square(RMS)***,a classification model with probability interpretation was established,and the cross-validation method was used for model *** research results show that the developed model is effective and reliable,and it has strong Reynolds number generalization *** developed model was theoretically analyzed in depth,and the effect of parameters on the model was studied in *** with the traditional RMS criterion,a reasonable transition zone can be obtained using the developed classification *** addition,the developed model does not require comparison of multi-point *** developed supervised learning model provides new ideas for the transition detection in flight experiments and other experiments.

关键词： Classification model Hidden Markov model Markov chain model Supervised learning Transition judgment

Variable slip window technology in transition detection on pitching airfoil

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2020年第4期33卷 1166-1180页

作者： Binbin WEI yongwei gao Dong LI Lei DENG School of Aeronautics Northwestern Polytechnical UniversityXi'an 710072China

In the pitching motion,the unsteady transition and relaminarization position plays an important role in the dynamic characteristics of the *** order to facilitate the computer to automatically and accurately calculate the position of the transition and relaminarization,a Variable Slip Window Technology(VSWT)suitable for airfoil dynamic data processing was developed using the S809 airfoil experimental data in this paper and two calculation strategies,i.e.,global strategy and single point strategy,were proposed:global strategy and single point *** core of the VSWT is the selection of the window function h and the parameters setting in the h *** effect of the VSWT was evaluated using the dimensionless pulse strength value(INB),which can be used to evaluate the signal characteristics,of the root mean square(RMS)value of the fluctuating *** is found that:the h function characteristics have a significant influence on the *** suitable functions are Hn function constructed in this paper and step *** the left boundary of the magnified area,the step function can obtain the largest INB value,but the robustness is not *** H1 function(Gaussian-like function,n=1)can show higher robustness while ensuring a large INB *** two computing strategies,which are single point strategy and global strategy,have their own advantages and *** former strategy,that is the single point strategy,can achieve a higher INB value,but the RMS magnification at the feature position needs to be known in *** the INB value obtained by the latter strategy,that is the global strategy,is slightly smaller than the calculation results of the former strategy,it is not necessary to know the RMS magnification at the feature position in *** the global strategy has better *** experimental data of NACA0012 airfoil was used to further validate the developed VSWT in this paper,and the results show that the VSWT develope

关键词： Data processing Dynamic characteristics Pitching airfoil Transition and relaminarization Variable slip window technology(VSWT)

Experimental and numerical study on dynamic stall under a large Reynolds number

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Advances in Aerodynamics 2023年第1期5卷 312-331页

作者： Binbin Wei yongwei gao Shuling Hu School of Aerospace Engineering Xi’an Jiaotong UniversityXi’an 710049China School of Aeronautics Northwestern Polytechnical UniversityXi’an 710072China

Dynamic stall under large Reynolds numbers and large reduced frequencies has a significant effect on the performance of the wind turbine blades,helicopter rotors,*** the dynamic stall physics of the NACA0012 airfoil under a large Reynolds number of Re=1.5×10^(6) was studied using experimental and numerical *** reduced frequency range was k=*** unsteady flow field in dynamic stall was studied in detail by using the transient pressure measurement and the numerical simulation based on the unsteady Reynolds-averaged Navier-Stokes(URANS)*** the time-frequency characteristics of the dynamic stall were studied using the wavelet *** study showed that the aerodynamic performance during the dynamic stall was dominated by the shear layer vortex(SLV)and the leading edge vortex(LEV),and the phase difference between the SLV and the LEV was the key factor in the exist-ence of the bimodal characteristics of the aerodynamic force/*** was a significant linear correlation between the negative peak of the vortex-induced Cp and the Cn in the reduced frequency range studied in this *** the convection of the near-wall LEV to the trailing edge,the high-frequency features firstly decay,and the multi-scale structures of the LEV become more significant as the reduced frequency gradually increases.

关键词： Dynamic stall Dynamic stall vortex(DSV) Leading edge vortex(LEV) Time-frequency analysis Wavelet analysis

Experimental study on transition of dynamic airfoil in pitching oscillation

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Advances in Aerodynamics 2023年第1期5卷 212-228页

The transition characteristics of dynamic airfoil have significant effects on the aerodynamic performance of wind turbines,helicopter rotor blades,jet engine compressor blades,*** time domain and time-frequency domain characteristics of transition on a NACA0012 airfoil during its pitching oscillation were experimentally studied using wall pressure measurement technology with high time accuracy in this *** vari-able slip window technology was used to detect the transition position,and the proper orthogonal decomposition(POD)method and wavelet analysis were combined to perform the time-frequency *** the gradual forward movement of the transi-tion,the low-frequency instability is gradually enhanced by the main flow and the inverse pressure gradient,and significantly submerges the high-frequency fluctuated *** higher order moments of the wall pressure during dynamic airfoil transi-tion deviate significantly from the Gaussian characteristics,which is caused by the low-frequency instability and high-frequency *** POD method is able to distinguish low-frequency instability from the high-frequency *** reduced frequency had significant effects on the *** the increase of the reduced frequency,the hysteresis effect of the transition became more and more significant,and the fre-quency component of transition was more concentrated and the energy was stronger.

关键词： Transition Dynamic airfoil Fluctuating pressure Wavelet analysis POD

A novel wall interference correction method for airfoil

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Advances in Aerodynamics 2024年第1期6卷 18-38页

作者： Binbin Wei yongwei gao Ruiyang Qiao Shuling Hu School of Aerospace Engineering Xi’an Jiaotong UniversityXi’an 710049China School of Aeronautics Northwestern Polytechnical UniversityXi’an 710072China National Key Laboratory of Aircraft Configuration Design Xi’an 710072China

Corrections for wind tunnel experimental results are crucial when accounting for tun-nel wall *** study introduces a new method,the non-uniform wall pres-sure signature method(NUWPSM),which is designed to address tunnel wall interfer-ence in *** improved wall pressure signature method(WPSM),an enhanced version of the WPSM,is developed to address the velocity disparities and systematic errors in pressure measurements between with and without model ***-thermore,the NUWPSM considers the non-uniformity of the flow induced by the lim-ited far-field effect in wind tunnel *** experimental data from three different scaled models of the WA210 airfoil,the efficacy of both the Improved WPSM and NUWPSM is *** indicate that the Improved WPSM exhibits superior capabilities in simulating the distribution of axial induced velocity along the wall com-pared to the traditional ***,both the Improved WPSM and NUWPSM demonstrate comparable abilities in correcting tunnel wall interference,achiev-ing precise corrections within an angle of attack range of-180°to+180°.Notably,the NUWPSM effectively captures the velocity non-uniformity induced by the limited far-field effect,thereby extending its applicability to a broader range of ***,the NUWPSM showcases enhanced robustness by eliminating human intervention in the singularity quantity and distribution.

关键词： Wind tunnel experiment Wall interference Wall interference correction Airfoil Non-uniform wall pressure signature method

Effect of vortex generator spanwise height distribution pattern on aerodynamic characteristics of a straight wing

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Advances in Aerodynamics 2023年第1期5卷 68-82页

作者： Lishu Hao Bao Hu yongwei gao Binbin Wei School of Aeronautics Northwestern Polytechnical UniversityXi’an 710072China School of Aerospace Engineering Xi’an Jiaotong UniversityXi’an 710049China

Vortex generator(VG)is a passive flow control technology,which can effectively inhibit flow ***,significant research efforts have been devoted to the study on the application of VG in airfoil,wing/blade and aircraft flow separation ***,the research on the variable height distribution of VG along the wingspan still *** study focuses on the experimental investigation of the influence of variable height distribution of ramp VG on aerodynamic ***,VG was designed,such that it was composed of two parts,one fixed region and one deformed region,which allowed for height *** height of VGs along the wingspan presented equal-height,triangular and trapezoidal distribution,forming a total of 15 VG ***,the connection mode of the model,the change of angle of attack and the collection and processing of aerodynamic data were ***,a wind tunnel experiment was performed to investigate the influence of height distribution of VG on aerodynamic characteristics of *** experimental results show that:(1)the height distribution of the three types of VGs could inhibit the stall flow and improve the aerodynamic performance of the wing;(2)“Triangular translation 3”and“Trapezoi-dal translation 2”were the best layouts,both of which could increase the maximum lift coefficient,delay stall,and significantly increase the lift-to-drag ratio at high angle of attack;(3)the influence of VG height and position factors on wing stall characteristics was analyzed by using the rough set theory,and the key position information of VG arrangement was *** study indicates that the variable height distribution is obviously better than the equal height distribution,which can provide ideas and refer-ences for the active control of variable height distribution of VGs.

关键词： Vortex generator Flow control Rough set theory Wind tunnel experiment

A conceptual design for deflection device in VTDP system

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Advances in Aerodynamics 2021年第1期3卷 29-48页

作者： yongwei gao Jianming Zhang Long Wang Bingzhen Chen Binbin Wei School of Aeronautics Northwestern Polytechnical University127 West Youyi RoadBeilin DistrictXi’anShaanxi 710072People’s Republic of China

The effectiveness of the Vectored Thrust Ducted Propeller(VTDP)system is not high currently,especially the lateral force is not large ***,a conceptual design for a deflection device of a VTDP system was proposed to achieve effective hovering *** magnitude of the lateral force that was applied to maintain balance while hovering was examined.A comparison between the experimental and numerical results for the 16H-1 was made to verify the numerical simulation *** deflection devices of the X-49 and the proposed design were analyzed using numerical *** results indicated that a larger lateral force and lower power consumption were presented in the proposed *** results of this article provide a new idea for the design of the VTDP system.

关键词： Vectored thrust ducted propeller Conceptual design Wind tunnel experiment Numerical simulation

深埋复杂条件下钠蒙脱石水化的分子动力学模拟研究

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

岩土工程学报 2025年第3期47卷 599-607页

作者：王跃鹏唐世斌刘向君王培峰高永伟杨赟梁利喜大连理工大学建设工程学院辽宁大连116024 西南石油大学油气藏地质及开发工程国家重点实验室四川成都610500 陕西寒湘能源科技有限公司陕西西安710032 中国石油集团川庆钻探工程有限公司钻采工程技术研究院陕西西安710018

黏土矿物水化作用引发的岩石结构解体现象与边坡滑坡、隧道塌方及钻井井壁坍塌等工程安全问题息息相关。为揭示深埋复杂条件下钠蒙脱石水化机理,运用分子模拟技术,开展了不同埋藏深度条件下钠蒙脱石水化过程的分子动力学模拟实验,验证... 详细信息

黏土矿物水化作用引发的岩石结构解体现象与边坡滑坡、隧道塌方及钻井井壁坍塌等工程安全问题息息相关。为揭示深埋复杂条件下钠蒙脱石水化机理,运用分子模拟技术,开展了不同埋藏深度条件下钠蒙脱石水化过程的分子动力学模拟实验,验证了钠蒙脱石的水化膨胀特性,实现了对其水化过程中关键物理化学参数的定量分析。模拟结果表明,晶层间距随着层间含水率的增加而阶梯型上升,呈现分层现象。随着埋藏深度和层间含水率增加,钠蒙脱石体积增大,而密度相应减小。层间含水率增加,促进氢键增多,并显著提升水分子和Na^(+)离子的自扩散系数。深埋条件下,水分子及Na^(+)离子自扩散系数较常温常压显著增大。随着水分子层数的递增,Na-Ow、Na-Hw、Ow-Hw(水分子间),Ow-Ow以及Os-Hw的主峰峰值,呈现出逐渐减弱的趋势,而在不同埋藏深度条件下,这些主峰峰值则表现出差异性。随着水分子层数的增加,水的聚合程度先增加后有所降低,Na^(+)离子的配位数降低、聚合程度下降、离子水化数和水化半径变小。随着埋藏深度的增加,水的聚合程度差别很小,Na^(+)离子对应水化特征仅有微小降低趋势。该研究成果可用于指导石油钻井、煤层安全开采、边坡稳定性评估及隧道工程开挖等关键领域的理论分析与工程实践。

关键词：钠蒙脱石水化机理分子动力学模拟径向分布函数自扩散系数离子配位数

Aerosol transportation in horizontal channels w让h gravitational effects

维普期刊数据库

同方期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Particuology 2019年第3期17卷 159-168页

作者： yongwei gao Ke Zhong Yanming Kang School of Environmental Science and Engineering Donghua University Shanghai 201620 China School of Physics and Electronic-Electrical Engineering Ningxia University Yinchuan 750021 China

Aerosol particle deposition in a narrow horizontal channel with gravitational effects is studied in the laminar flow regime. A general explic让 solution for predicting the aerosol transportation in the channel is obtained theoretically. The characteristics of the asymmetric concentratio n profiles and their dependence on gravitational settling are analyzed for different settings of the diffusion and sedimentation parameters. Aerosol deposition on the channel walls, which is influenced by a combination of mechanisms, is also analyzed. The results are compared with those from simplified models obtained in previous studies in which only diffusion or gravity was considered. The analysis reveals that the literature results regarding this aspect may be simplified with the present solution under specific conditions.

关键词： Exact solution Combined deposition Gravitational effect Horizontal channel Asymmetric distribution