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High-dimensional aerodynamic data modeling using a machine learning method based on a convolutional neural network

Advances in aerodynamics 2022年第1期4卷 845-875页

作者： Bo-Wen Zan Zhong-Hua Han Chen-Zhou Xu Ming-Qi Liu Wen-Zheng Wang Institute of Aerodynamic and Multidisciplinary Design Optimization National Key Laboratory of Science and Technology On Aerodynamic Design and ResearchSchool of AeronauticsNorthwestern Polytechnical UniversityXi’an710072China Aircraft Swarm Intelligent Sensing and Cooperative Control Key Laboratory of Sichuan Province School of Aeronautics and AstronauticsUniversity of Electronic Science and Technology of ChinaChengdu611731China

Modeling high-dimensional aerodynamic data presents a significant challenge in aero-loads prediction, aerodynamic shape optimization, flight control, and simulation. This article develops a machine learning approach based on a convolutional neural network (CNN) to address this problem. A CNN can implicitly distill features underlying the data. The number of parameters to be trained can be significantly reduced because of its local connectivity and parameter-sharing properties, which is favorable for solving high-dimensional problems in which the training cost can be prohibitive. A hypersonic wing similar to the Sanger aerospace plane carrier wing is employed as the test case to demonstrate the CNN-based modeling method. First, the wing is parameterized by the free-form deformation method, and 109 variables incorporating flight status and aerodynamic shape variables are defined as model input. Second, more than 7000 sample points generated by the Latin hypercube sampling method are evaluated by performing computational fluid dynamics simulations using a Reynolds-averaged Navier-Stokes flow solver to obtain an aerodynamic database, and a CNN model is built based on the observed data. Finally, the well-trained CNN model considering both flight status and shape variables is applied to aerodynamic shape optimization to demonstrate its capability to achieve fast optimization at multiple flight statuses.

关键词： aerodynamic data modeling High-dimensional problem Machine learning Convolutional neural network Computational fluid dynamics

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Effect of longitudinal lift distribution on sonic boom of a canard-wing-stabilator-body configuration

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Chinese Journal of Aeronautics 2023年第6期36卷 92-108页

作者： Liwen ZHANG Zhonghua HAN Jianling QIAO Wenping SONG Yulin DING Xuehe WANG Institute of Aerodynamic and Multidisciplinary Design Optimization School of AeronauticsNorthwestern Polytechnical UniversityXi'an 710072China National Key Laboratory of Science and Technology on Aerodynamic Design and Research School of AeronauticsNorthwestern Polytechnical UniversityXi'an 710072China Research Center for Environment-friendly Supersonic Civil Transport Northwestern Polytechnical UniversityXi'an 710072China

After the last flight of the Concorde in 2003,sonic boom has been one of the obstacles to the return of a supersonic transport aircraft to *** reduce the sonic boom intensity to an acceptable level,it is of great significance to study the effect of lift distribution on far-field sonic boom,since lift is one of the most important contributors to an intense sonic *** studies on the longitudinal lift distribution used low-fidelity methods,such as Whitham theory,and in turn,only preliminary conclusions were obtained,such as that extending the lift distribution can reduce sonic *** paper uses a newly developed high-fidelity prediction method to quantitatively study the effect of longitudinal lift distribution on the sonic boom of a Canard-Wing-Stabilator-Body(CWSB)*** high-fidelity prediction method combines near-feld CFD simulation with far-field propagation by solving the augmented Burgers equation.A multipole analysis method is employed for the extraction of near-field waveform in order to reduce computational *** configurations with the same total lift but different distributions are studied,and the quantitative relationship between the longitudinal lift distribution and far-field sonic boom intensity is *** is observed that a small lift generated by the stabilator can prevent aft-stabilator and aft-fuselage shocks from merging,while the balanced lift generated by the canard and wing can effectively keep the corresponding shocks further apart,which is beneficial for reducing both the on-track and off-track sonic *** turn,the acoustic level perceived at the ground can be reduced by 5.9 PLdB on-track and 5.4 PLdB off-track,on average.

关键词： Computational fluid dynamics Longitudinal lift distribution Sonic boom Sonic boom reduction Supersonic transport

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Reconstruction of particle distribution for tomographic particle image velocimetry based on unsupervised learning method

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Particuology 2024年第10期93卷 349-363页

作者： Duanyu Zhang Haoqin Huang Wu Zhou Mingjun Feng Dapeng Zhang Limin Gao School of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai200093China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer for Power Engineering University of Shanghai for Science and TechnologyShanghai200093China National Key Laboratory of Aerodynamic Design and Research Northwestern Polytechnical UniversityXi'an710072China

The development of deep learning has inspired some new methods to solve the 3D reconstruction problem for Tomographic Particle Image Velocimetry (Tomo-PIV). However, the supervised learning method requires a large number of data with ground truth as training information, which is very difficult to gather from experiments. Although synthetic datasets can be used as alternatives, they are still not exactly the same with the real-world experimental data. In this paper, an Unsupervised Reconstruction Technique based on U-net (UnRTU) is proposed to reconstruct volume particle distribution explicitly. Instead of using ground truth data, a projection function is used as an unsupervised loss function for network training to reconstruct particle distribution. The UnRTU was compared with some traditional algebraic reconstruction algorithms and supervised learning method using synthetic data under different particle density and noise level. The results indicate that UnRTU outperforms these traditional approaches in both reconstruction quality and noise robustness, and is comparable to the supervised learning methods AI-PR. For experimental tests, particles dispersed in cured epoxy resin are moved by an electric rail with a certain speed to obtain the ground truth data of particle velocity. Compared with other algorithms, the reconstructed particle distribution by UnRTU has the best reconstruction fidelity. And the accuracy of the 3D velocity field estimated by UnRTU is 12.9% higher than that from the traditional MLOS-MART algorithm. It demonstrates significant potential and advantages for UnRTU in 3D reconstruction of particle distribution. Finally, UnRTU was successfully applied to the high-speed planar cascade airflow field, demonstrating its applicability for measuring complex fluid flow fields at higher particle density.

关键词： Tomographic particle image velocimetry 3D reconstruction Unsupervised learning Convolutional neural network

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Influence of leading edge with real manufacturing error on aerodynamic performance of high subsonic compressor cascades

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Chinese Journal of Aeronautics 2021年第6期34卷 220-232页

作者： Chi MA Limin GAO Haohao WANG Ruiyu LI Baohai WU School of Power and Energy Northwestern Polytechnical UniversityXi’an 710129China The National Key Laboratory of Aerodynamic Design and Research Xi'an 710129China Key Laboratory of Contemporary Design and Integrated Manufacturing Technology of Ministry of Education Northwestern Polytechnical UniversityXi'an 710072China

To investigate the influence of real leading-edge manufacturing error on aerodynamic performance of high subsonic compressor blades,a family of leading-edge manufacturing error data were obtained from measured compressor *** the limited samples,the leadingedge angle and leading-edge radius distribution forms were evaluated by Shapiro-Wilk test and quantile–quantile *** statistical characteristics provided can be introduced to later related *** parameterization design method B-spline and Bezier are adopted to create geometry models with manufacturing error based on leading-edge angle and leading-edge *** influence of real manufacturing error is quantified and analyzed by self-developed non-intrusive polynomial chaos and Sobol’*** mechanism of leading-edge manufacturing error on aerodynamic performance is *** results show that the total pressure loss coefficient is sensitive to the leading-edge manufacturing error compared with the static pressure ratio,especially at high ***,manufacturing error of the leading edge will influence the local flow acceleration and subsequently cause fluctuation of the downstream *** aerodynamic performance is sensitive to the manufacturing error of leading-edge radius at the design and negative incidences,while it is sensitive to the manufacturing error of leading-edge angle under the operation conditions with high incidences.

关键词： aerodynamic performance Compressor cascade Limited measurement data Manufacturing error Uncertainty analysis

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design strategy and relevant flow mechanisms of highly loaded 3D compressor tandem cascades

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Chinese Journal of Aeronautics 2024年第7期37卷 220-235页

作者： Xiaochen MAO Yunyu WANG Zhihua DING Hao CHENG Bo LIU School of Power and Energy Northwestern Polytechnical UniversityXi’an 710129China The National Key Laboratory of Science and Technology on Aerodynamic Design and Research Xi’an 710129China Xi’an Thermal Power Research Institute Co.Ltd Xi’an 710072China

To investigate the design strategy of highly loaded tandem cascades at both the midspan and endwall,the overall performance and flow mechanisms of four typical tandem cascades based on the optimization were analyzed from multiple perspectives *** results show that the interference effects on the Front Blade(FB)and Rear Blade(RB)should not be overlooked during the design phase,and the design strategies at the midspan and endwall are completely *** the midspan,the optimization aims to increase the interference effects and the strength of the gap jet while maintaining the same load on the FB and ***,the endwall optimal airfoil exhibits weakening interference effects,advancement of the gap jet location,and load transfer from the FB to *** further analysis of flow characteristics,the midspan optimal airfoil is beneficial for inhibiting the low-energy fluid from interacting with the suction surface of RB under the design condition,but results in earlier occurrence of corner *** endwall optimal airfoil helps suppress the development of the secondary flow and delay the onset of corner ***,by combining the benefits of these two design approaches,additional forward sweep effects are achieved,further enhancing the performance of the tandem cascade.

关键词： Tandem cascade Interference effect Vortex structure Load split Compressor

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ANALYSIS AND CONTROL OF DYNAMIC STALL CHARACTERISTICS OF S809 AIRFOIL 32

ANALYSIS AND CONTROL OF DYNAMIC STALL CHARACTERISTICS OF S80...

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32nd Congress of the International Council of the Aeronautical sciences, ICAS 2021

作者： Hao, Li-Shu Gao, Yong-Wei Wei, Bin-Bin Hu, Bao National Key Laboratory of Science and Technology on Aerodynamic Design and Research Northwestern Polytechnical University Xi'an710072 China

ISBN: (纸本)9783932182914

With the development of renewable energy, the utilization of wind power has made remarkable progress and the wind power become the main clean energy. In this work, the effects of different parameters on the dynamic stall of S809 airfoil were studied by using time-resolved pressure measurement technique, including mean angle of attack (AoA), reduced frequency and Reynolds number. In addition, the control effect of Gurney flap on the dynamic stall characteristics of S809 airfoil was also studied. The results showed that the reduced frequency had a significant effect on the dynamic stall characteristics of the airfoil. With the reduced frequency increasing, the hysteresis effect of aerodynamic characteristics increased gradually in the dynamic stall phase. Gurney flap had a significant control effect on the dynamic stall characteristics of the airfoil. With the increase of flap height, the normal force coefficient of airfoil moves up and the pitching moment coefficient moves down, which played a significant effect of lift increase. © 2021 32nd Congress of the International Council of the Aeronautical sciences, ICAS 2021. All rights reserved.

关键词： Airfoils

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FAST METHOD AND AN INTEGRATED CODE FOR SONIC BOOM PREDICTION OF SUPERSONIC COMMERCIAL AIRCRAFT 32

FAST METHOD AND AN INTEGRATED CODE FOR SONIC BOOM PREDICTION...

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32nd Congress of the International Council of the Aeronautical sciences, ICAS 2021

作者： Ding, Yu-Lin Han, Zhong-Hua Qiao, Jian-Ling Song, Wen-Ping Song, Bi-Feng Institute of Aerodynamic and Multidisciplinary Design Optimization National Key Laboratory of Science and Technology on Aerodynamic Design and Research School of Aeronautics Northwestern Polytechnical University Xi'an710072 China

ISBN: (纸本)9783932182914

Sonic boom prediction plays a significant role in the preliminary design of next-generation supersonic commercial aircraft. There is an enormous demand of sonic boom evaluations in a preliminary design stage, during which a suitable configuration needs to be determined through extensive modifications and evolutions. Therefore, it is of great interest to develop a robust, efficient and reasonably accurate sonic boom prediction method. A modified linear method is developed for sonic boom prediction to address the enormous computational cost associated with preliminary design. Aiming at improving prediction accuracy, a more reasonable method for calculating equivalent area distribution is applied. To be specific, calculation method of equivalent area distribution due to volume and lift is presented, which can improve the accuracy of the prediction. An integrated code named FA-Boom for fast sonic boom prediction is developed and its accuracy and efficiency is validated by comparison with high-fidelity result as well as experimental data. © 2021 32nd Congress of the International Council of the Aeronautical sciences, ICAS 2021. All rights reserved.

关键词： Forecasting

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High-order mesh generation using RBFs based on geometrical similarity 10

High-order mesh generation using RBFs based on geometrical s...

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10th International Conference on Computational Fluid Dynamics, ICCFD 2018

作者： Zhao, Zi-Hao Song, Wen-Ping Song, Ke National Key Laboratory of Science and Technology on Aerodynamic Design and Research Northwestern Polytechnical University Xi'an710072 China

This paper proposes a method to generate high-order curvilinear mesh using compact radial basis function (RBF) interpolation with optimized support radius. We start with an initial high-order linear mesh, and relocate the boundary nodes to their true positons on the true curved geometry. Then the rest mesh nodes are moved using RBF interpolation based on boundary nodes displacement. However, if one assigns identical support radius to all control points, the interpolation might result in poor-quality or even invalid mesh elements. In this article, we present an optimization process to determine a proper set of support radius. Additionally, a novel and fast curved mesh quality estimation based on geometrical similarity between linear and curvilinear mesh element is used to speed up the optimization process. A number of examples including highly stretched boundary layer meshes of complex geometries are tested, the results illustrate that our method is able to produce high quality curved meshes with low computational cost. © ICCFD 2018.

关键词： Mesh generation

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Optimal design Criteria of Tandem Configuration for High-Load Compressor Cascades

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Journal of Thermal science 2024年第6期33卷 2047-2058页

作者： MAO Xiaochen JIAO Yingchen CHENG Hao ZHANG Botao LIU Bo School of Power and Energy Northwestern Polytechnical UniversityXi'an 710129China The National Key Laboratory of Science and Technology on Aerodynamic Design and Research Xi'an 710129China Xi'an Thermal Power Research Institute Co. Ltd.Xi'an 710072China

Axial overlap(AO)and percent pitch(PP)are considered as key position configuration parameters that affect the tandem cascade *** objective of the current study is to investigate the optimal design criteria for these two parameters in tandem cascades of subsonic highly-loaded two-dimensional *** that,the influence mechanisms of AO and PP are explored *** results show that higher PP is beneficial for decreasing rear blade(RB)load,but an invalidity of gap flow occurs when it approaches *** change in AO has an influence on the adverse pressure gradient of the front blade(FB),and it also affects the gap flow strength and FB wake ***,the optimal design criteria for AO and PP are obtained in a large design space,which clarifies the matching relationship of the two parameters at different operating *** best global range of AO is about-0.05 to 0.05 while PP is between 0.85 to 0.92,and PP should be smaller to avoid performance degradation as AO *** to the fault tolerance in practical applications,PP should be closer to the lower bound to ensure that the deterioration boundary is wide enough.

关键词： axial compressor tandem cascade axial overlap percent pitch optimal design criteria

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Numerical investigation of flow over multielement airfoils with lift-enhancing tabs

Numerical investigation of flow over multielement airfoils w...

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28th Congress of the International Council of the Aeronautical sciences 2012, ICAS 2012

作者： Zhang, Zhenhui Li, Dong National Key Laboratory of Science and Technology on Aerodynamic Design and Research Northwestern Polytechnical University Xi'an 710072 China

ISBN: (纸本)9781622767540

The flow over multi-element airfoils with flatplate lift-enhancing tabs placed near the trailing edge of main element or/and flap was numerically investigated for different flap riggings. The 2D unsteady Reynolds-Averaged Navier-Stokes (RANS) equations together with the two-equation SST k-ω turbulence model were applied to this numerical simulation utilizing the multi-block structured grids of C-H type. The effects of local grid near the liftenhancing tabs on computational results and also various tabs were studied for McDonnell Douglas Aerospace three-element airfoils consisting of a slat and single-slotted flap. Numerical results showed that the impact of liftenhancing tabs on the performance of multielement airfoils depended on the location and height of tabs and multi-element configurations. The cove tab could reduce the amount of separated flow on the flap being in nonoptimum position, whereas the flap tab could substantially increase the lift of multi-element airfoils for different configurations, and the combination tab was approximately a linear combination of the changes caused by the individual tabs.

关键词： Turbulence models

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