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Wing aeroelasticity analysis based on an integral boundary-layer method coupled with Euler solver

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Chinese Journal of Aeronautics 2016年第5期29卷 1262-1272页

作者： Ma Yanfeng He Erming Zeng Xianang Li Junjie School of Aeronautics Northwestern Polytechnical University Xi'an Shaanxi 710072 China avic Xi'an aircraft Design and Research institute Xi'an Shaanxi 710089 China

An interactive boundary-layer method, which solves the unsteady flow, is developed for aeroelastic computation in the time domain. The coupled method combines the Euler solver with the integral boundary-layer solver （Euler/BL） in a ＂semi-inverse＂ manner to compute flows with the inviscid and viscous interaction. Unsteady boundary conditions on moving surfaces are taken into account by utilizing the approximate small-perturbation method without moving the computational grids. The steady and unsteady flow calculations for the LANN wing are presented. The wing tip displacement of high Reynolds number aero-structural dynamics （HIRENASD） Project is simulated under different angles of attack. The flutter-boundary predictions for the AGARD 445.6 wing are provided. The results of the interactive boundary-layer method are compared with those of the Euler method and experimental data. The study shows that viscous effects are significant for these cases and the further data analysis confirms the validity and practicability of the coupled method.

关键词： Aeroelasticity Flutter Integral boundary-layer Transonic flow Unsteady flow

Static solution on four-region spherial cavity expansion model in a pressure sensitive medium

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Journal of Harbin institute of Technology(New Series) 2010年第3期17卷 405-408页

作者：于雪梅唐立强杨勇 College of Aerospace and Civil Engineering Harbin Engineering University avic Harbin aircraft Industry Group Co.LTD. Aircraft Design Institute

Spherical cavity expansion model is often used to study the mechanic characteristics of pressure sensitive mediums. The most important one we do in the paper is that we construct a four-region model with σθ≠0 in damage region,which is different from what Satapathy did before and is more reasonable. By adopting this model,different constitutive equations were constructed by different method-elastic mechanics in elastic region,damage mechanics and fracture mechanics in damage region,and macro-micro mechanics theory in plastic region. Then using Durban's self-similarity assumption,the control differential equations with boundary conditions were established,and the static numerical solution of stress field and displacement field in the three different regions of elastic,damage and plastic area were discussed respectively. Results showed that this four-region model can describe precisely the mechanic characteristics of pressure sensitive mediums under initial pressure.

关键词： pressure-sensitive material spherical cavity expansion damage mechanics self-similarity assumption constitutive equation

Modeling and control of a novel electro-hydrostatic actuator with adaptive pump displacement

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Chinese Journal of Aeronautics 2020年第1期33卷 365-371页

作者： Yan WANG Shengrong GUO Hongkang DONG School of Transportation Science and Engineering Beihang UniversityBeijing 100083China Nanjing Engineer institute of aircraft System Jincheng AVICNanjing 211100China

The variable pump displacement and variable motor speed electro-hydrostatic actuator(EHA),one of the three types of EHAs,has advantages such as short response time,flexible speed regulation,and high ***,the nonlinearity of its double-input single-output system poses a great challenge for system *** study proposes a novel EHA with adaptive pump displacement and variable motor speed(EHA-APVM).A closed-loop position is realized using a ***,the displacement varies with the system pressure;thus,the EHA-APVM is a single-input and single-output ***,the working principles of the EHA-APVM and the pump used in the system are ***,a nonlinear mathematical model of the proposed EHA-APVM control system is established,and a feedback back-stepping(FBBS)control algorithm is introduced to transform the complex nonlinear system into a linear system on the basis of the back-stepping control ***,simulation results prove that the EHA-APVM has a quick response and high robustness to variations of the load and the pump *** this work,the size and weight of the motor are significantly reduced because the maximum power requirement is reduced,which is very beneficial for using the actuator in airborne equipment.

关键词： Adaptive displacement pump Back-stepping control Electro-hydrostatic actuator Feedback linearization Robustness

Reflected shock/turbulent boundary layer interaction structure analysis based on large eddy simulation

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Chinese Journal of Aeronautics 2021年第5期34卷 364-372页

作者： Dongdong ZHONG Lixu WANG Ning GE College of Energy and Power Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China Nanjing Engineering institute of aircraft Systems AVICNanjing 210016China

In order to understand the physical phenomenon of the reflected shock/turbulent boundary layer interaction,the Large Eddy Simulation(LES)is conducted to investigate shock wave and turbulent boundary layer interaction in a 12°compression ramp with inlet high Mach number of ***/recycling method is used as inflow turbulence generation technique and validated on a supersonic flat plate turbulent boundary *** flow field of recycling plane in the plate computation domain is obtained to give the inlet boundary condition for the LES *** paper focuses on the reflected shock/turbulent boundary layer interaction region,where the fine flow structure and instantaneous flow field are analyzed in *** is found that the unsteady motion of the shock wave leads to the increase of wall pressure fluctuation.

关键词： Large eddy simulation Reflected STBLI Rescaling/recycling method Shock motion Turbulent

Bayesian uncertainty analysis of SA turbulence model for supersonic jet interaction simulations

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Chinese Journal of Aeronautics 2022年第4期35卷 185-201页

作者： Jinping LI Shusheng CHEN Fangjie CAI Sheng WANG Chao YAN School of Aeronautic Science and Engineering Beihang UniversityBeijing 100083China School of Aeronautics Northwestern Polytechnical UniversityXi'an 710072China avic the first aircraft institute Xi'an 710089China China Academy of Launch Vehicle Technology Beijing 100076China

The Reynolds Averaged Navier-Stokes(RANS) models are still the workhorse in current engineering applications due to its high efficiency and robustness. However, the closure coefficients of RANS turbulence models are determined by model builders according to some simple fundamental flows, and the suggested values may not be applicable to complex flows, especially supersonic jet interaction flow. In this work, the Bayesian method is employed to recalibrate the closure coefficients of Spalart-Allmaras(SA) turbulence model to improve its performance in supersonic jet interaction problem and quantify the uncertainty of wall pressure and separation length. The embedded model error approach is applied to the Bayesian uncertainty analysis. firstly, the total Sobol index is calculated by non-intrusive polynomial chaos method to represent the sensitivity of wall pressure and separation length to model parameters. Then, the pressure data and the separation length are respectively served as calibration data to get the posterior uncertainty of model parameters and Quantities of Interests(Qo Is). The results show that the relative error of the wall pressure predicted by the SA turbulence model can be reduced from 14.99% to 2.95% through effective Bayesian parameter estimation. Besides, the calibration effects of four likelihood functions are systematically evaluated. The posterior uncertainties of wall pressure and separation length estimated by different likelihood functions are significantly discrepant, and the Maximum a Posteriori(MAP) values of parameters inferred by all functions show better performance than the nominal values. Finally, the closure coefficients are also estimated at different jet total pressures. The similar posterior distributions of model parameters are obtained in different cases, and the MAP values of parameters calibrated in one case are also applicable to other cases.

关键词： Bayesian calibration MAP estimation SA turbulence model Supersonic jet interaction Uncertainty quantification

DETERMINATION OF CRACK SURFACE DISPLACEMENTS FOR A RADIAL CRACK EMANATING FROM A SEMI-CIRCULAR NOTCH USING WEIGHT FUNCTION METHOD

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Acta Mechanica Solida Sinica 2015年第3期28卷 305-312页

作者： Dihua Tong Xueren Wu avic Beijing institute of Aeronautical Materials

A radial crack emanating from a semi-circular notch is of significant engineering importance. Accurate determination of key fracture mechanics parameters is essential for damage tolerance design and fatigue crack growth life predictions. The purpose of this paper is to provide an efficient and accurate closed-form weight function approach to the calculation of crack surface displacements for a radial crack emanating from a semi-circular notch in a semi-infinite plate. Results are presented for two load conditions： remote applied stress and uniform stress segment applied to crack surfaces. Based on a correction of stress intensity factor ratio, highly accurate analytical equations of crack surface displacements under the two load conditions are developed by fitting the data obtained with the weight function method. It is demonstrated that the Wu- Carlsson closed-form weight functions are very efficient, accurate and easy-to-use for calculating crack surface displacements for arbitrary load conditions. The method will facilitate fatigue crack closure and other fracture mechanics analyses where accurate crack surface displacements are required.

关键词： radial crack semi-circular notch Dugdale strip-yield model crack surface displacement weight function method

Deep learning for inverse design of low-boom supersonic configurations

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Advances in Aerodynamics 2023年第1期5卷 247-266页

作者： Shusheng Chen Jiyan Qiu Hua Yang Wu Yuan Zhenghong Gao School of Aeronautics Northwestern Polytechnical UniversityXi’an 710072China avic the first aircraft institute Xi’an 710089China Computer Network Information Center Chinese Academy of SciencesBeijing 100190China

Mitigating the sonic boom to an acceptable stage is crucial for the next generation of supersonic *** primary way to suppress sonic booms is to develop a low sonic boom aerodynamic shape *** paper proposes an inverse design approach to optimize the near-field signature of an aircraft,making it close to the shaped ideal ground signature after propagation in the *** introducing the Deep Neural Network(DNN)model for the first time,a predicted input of Augmented Burgers equation is inversely *** the K-fold cross-validation method,the pre-dicted ground signature closest to the target ground signature is ***,the corresponding equivalent area distribution is calculated using the classical Whitham’s F-function theory from the optimal near-field *** inversion method is vali-dated using the classic example of the C608 vehicle provided by the Third Sonic Boom Prediction Workshop(SBPW-3).The results show that the design ground signature is consistent with the target *** equivalent area distribution of the design result is smoother than the baseline distribution,and it shrinks significantly in the rear ***,the robustness of this method is verified through the inverse design of sonic boom for the non-physical ground signature target.

关键词： Low boom configuration Deep neural network Augmented Burgers equation Supersonic transports Equivalent area

Analysis of crack opening stresses for center- and edge-crack tension specimens

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Chinese Journal of Aeronautics 2014年第2期27卷 291-298页

作者： Tong Di-Hua Wu Xue-Ren avic Beijing institute of Aeronautical Materials

Accurate determination of crack opening stress is of central importance to fatigue crack growth analysis and life prediction based on the crack-closure model. This paper studies the crack opening behavior for center- and edge-crack tension specimens. It is found that the crack opening stress is affected by the crack tip element. By taking the crack tip element into account, a modified crack opening stress equation is given for the center-crack tension specimen. Crack surface displace- ment equations for an edge crack in a semi-infinite plate under remote uniform tension and partially distributed pressure are derived by using the weight function method. Based on these displacements, a crack opening stress equation for an edge crack in a semi-infinite plate under uniform tension has been developed. The study shows that the crack opening stress is geometry-dependent, and the weight function method provides an effective and reliable tool to deal with such geometry depen- dence.

关键词： Center- and edge-crack Crack closure Crack opening stresses Crack surface displacements Weight function method

Simulation and experimental investigation of inner-jet electrochemical grinding of GH4169 alloy

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Chinese Journal of Aeronautics 2018年第3期31卷 608-616页

作者： Hansong LI Shuxing FU Qingliang ZHANG Shen NIU Ningsong QU College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016 China avic Jincheng Nanjing Engineering institute of aircraft Systems Nanjing 211106 China

GH4169 alloy is one of the most commonly used materials in aero engine turbine blades,but its machinability is poor because of its excellent strength at high temperatures. Electrochemical machining（ECM） has become a common method for machining this alloy and other difficult-tomachine materials. Electrochemical grinding（ECG） is a hybrid process combining ECM and conventional grinding. In this paper, investigations conducted on inner-jet ECG of GH4169 alloy are described. Two types of inner-jet ECG grinding wheels were used to machine a flat bottom *** machining process was simulated using COMSOL software, and machining gaps under different machining parameters were obtained. In addition, maximum feed rates and maximum material removal rates under different machining parameters were studied experimentally. The maximum sizes and the uniformity of the distributions of the gaps machined by the two grinding wheels were compared. The effects of different applied voltages on the machining results were also investigated.

关键词： Electrochemical grinding GH4169 alloy Inner-jet Material removal rate Maximum feed rate