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Wing Flutter Prediction by a Small-Disturbance Euler Method on Body-Fitted Curvilinear Grids

AIAA JOURNAL 2019年第11期57卷 4873-4884页

作者： Pan, Jieyun Liu, Feng Peking Univ Coll Engn Beijing 100871 Peoples R China Univ Calif Irvine Dept Mech & Aerosp Engn Irvine CA 92697 USA

Time-accurate coupled fluid and structure solutions for the unsteady Euler equations are too expensive for routine aeroelastic computation. The small-disturbance Euler (SD-Euler) method is shown to be an efficient and accurate method for computation of the frequency-domain generalized aerodynamics forces, even in the transonic region. The SD-Euler method reduces the unsteady problem to a steady flow solution for the perturbation so that the generalized aerodynamics forces can be evaluated directly, enabling substantial reduction of computational time. A SD-Euler solver on body-fitted curvilinear grids has been developed and validated using two-dimensional airfoil and three-dimensional wing rigid-body pitching test cases. Frequency-domain flutter analyses of the Isogai wing model and the AGARD 445.6 weakened wing are performed using this new solver. Flutter boundary predictions by the SD-Euler method agree well with the results by a coupled fluid-structure method. The flutter mode shift phenomenon for the Isogai wing model and the AGARD 445.6 weakened wing is also demonstrated by using the frequency-domain method.

关键词： Navier Stokes Solver Freestream Mach Number Euler Equations Frequency Domain Two Dimensional Flow Two Dimensional Airfoil computational structural dynamics Shock Capturing Method Stiffness Matrices Reynolds Averaged Navier Stokes

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Multifidelity Aerodynamic Optimization of a Helicopter Rotor Blade

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AIAA JOURNAL 2019年第8期57卷 3132-3144页

作者： Bailly, Joelle Bailly, Didier Off Natl Etud & Rech Aerosp Aerodynam Aeroelast & Acoust Dept Helicopters Propellers & Turbomachinery Unit 8 Rue Vertugadins F-92190 Meudon France Off Natl Etud & Rech Aerosp Aerodynam Aeroelast & Acoust Dept Civil Aircraft Unit 8 Rue Vertugadins Meudon France

A multifidelity optimization technique is applied to the design of a helicopter rotor blade to improve its performance in forward flight. This optimization technique is based on a surrogate model that replaces the high-fidelity computational fluid dynamics (CFD)/computational structural dynamics (CSD) simulations necessary to capture the three-dimensional unsteady effects generated in the flowfield of a complex blade geometry. The single low-fidelity model based on kriging methodology and generated by lifting-line simulations leads to a power benefit of 2.5%, which is not reproducible by an a posteriori high-fidelity CSD/CFD computation. The optimization procedure using cokriging surrogate models based on two levels of fidelity (lifting-line and CSD/CFD simulations) leads to a realistic blade planform, for which the power benefit is estimated at 2.2%. This optimized solution, obtained after a factor-of-six reduction in CPU time, shows the advantages of using a cokriging surrogate model (rather than a single-fidelity kriging model) for aerodynamic optimizations.

关键词： Helicopter Blade Cumulative Distribution Function Surrogate Model CFD Simulation computational structural dynamics Aerodynamic Force Vector Aerodynamic Performance Design of Experiments Rotor Blades Genetic Algorithm

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Application of hover prediction methodologies to anhedral tip shapes 55

Application of hover prediction methodologies to anhedral ti...

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55th AIAA Aerospace Sciences Meeting

作者： Zhou, Chong Sankar, Lakshmi N Eschcol, Ritu Marpu Kim, Jeewoong School of Aerospace Engineering Georgia Institute of Technology AtlantaGA United States CD-adapco OrlandoFL United States Advance Rotorcraft Technology Inc. SunnyvaleCA United States

ISBN: (数字)9781624104473

ISBN: (纸本)9781624104473

A hybrid Navier-Stokes/Free Wake methodology, and a wake capturing methodology have been applied to helicopter rotors in hover. Two tip planforms were analyzed: S-76 rotor with a swept tip and a swept tip with anhedral. The solidity of the three rotors was matched. Calculations have been done for a range of pitch settings. Comparisons of the measurements against computed thrust, power, and figure of merit values have been done. Where available, comparisons with other calculations. The simulations are in reasonable agreement with published data for the thrust, power, and figure of merit. The sectional load data and the inflow over the rotor disk have been analyzed to understand the physical mechanisms that cause the anhedral tip to be more efficient than a conventional swept tip. It is concluded that the rotor with the anhedral tip has a more uniform inflow over the rotor disk, reducing the induced power and the total power. © 2017 by Lakshmi N. Sankar and Chong Zhou.

关键词： Helicopter Rotor Vortex Filaments Reynolds Averaged Navier Stokes Navier Stokes Simulation Applied Aerodynamics Message Passing Interface computational structural dynamics Elastic Deformation Turbulence Models Compressibility

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Restricted snakes: A flexible topology parameterisation method for aerodynamic optimisation 55

Restricted snakes: A flexible topology parameterisation meth...

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55th AIAA Aerospace Sciences Meeting

作者： Payot, A.D.J. Rendall, T.C.S. Allen, C.B. Department of Aerospace Engineering University of Bristol BristolBS8 1TR United Kingdom

ISBN: (数字)9781624104473

ISBN: (纸本)9781624104473

This paper presents the development of a novel parameterisation method for aerodynamics which allows topological flexibility. This new parameterisation method builds geometries using restricted snakes to recover Volume Of Solid (VOS) data under a minimum length constraint. Geometric inverse design results are presented showing the ability of the parameterisation to recover a range of aerodynamic shapes to a set tolerance. The Aerodynamic Design Optimization Discussion Group (ADODG) Eulerian drag minimisation of the NACA 0012 (case 1) was attempted using a conjugate gradient optimiser leading to a drag coefficient of 66 counts. Results of supersonic drag minimizations under an area constraint were compared against known linear optima, showing equivalent or better aerodynamic performance in all cases. The topological flexibility of the parametrisation allowed reductions in drag of 80% compared to the Busemann biplane, a multiplane profile predicted to have no wave drag at supersonic speed by linear theory. © 2017 by A. D. J. Payot;T. C. S. Rendall;C. B. Allen.

关键词： Aerodynamic Shape Optimization NACA 0012 Aerodynamic Performance Geometric Tolerances Supersonic Speed Sequential Quadratic Programming computational Fluid dynamics Supersonic Flow Commercial Aircraft computational structural dynamics

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Recent advances in scaling up complex fluid-structure interaction simulations 55

Recent advances in scaling up complex fluid-structure intera...

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55th AIAA Aerospace Sciences Meeting

作者： Löhner, Rainald Mut, Fernando Camelli, Fernando F. Figueroa, Alejandro Baum, Joseph D. Soto, Orlando A. Togashi, Fumiya Carrington, Laura Jundt, Adam Cauble-Chantrenne, Allyson Peraza, Joshua Tiwari, Ananta CFD Center M.S. 6A2 College of Science George Mason University Fairfax VA 22030-4444 USA Applied Simulations Inc. 1211 Pine Hill Road McLean VA 22101 USA EP Analytics Inc. 12121 Scripps Summit Drive Suite 130 San Diego CA 92131 USA

ISBN: (数字)9781624104473

ISBN: (纸本)9781624104473

The run-time performance of a typical ‘legacy’ code designed for a specific class of fluid- structure interaction problems has been increased considerably by a combination of careful code timings, run-time settings and algorithmic improvements. The most notable actions include: avoidance of multiple writes to the same file;maximizing the use of binary files for output;setting proper buffer sizes;avoidance of redundant subroutine calls;increased parallelization;algorithmic improvements for embedded and immersed techniques. The overall improvement ranged from factors of 1:2 to 1:8. Furthermore, the increased parallelization of the current scalability bottleneck code (CSD) has opened the possibility to utilize efficiently an order of magnitude higher number of processors for the flow codes. © 2017 by The authors.

关键词： Fluid Structure Interaction computational structural dynamics High Performance Computing Fluid dynamics computational Fluid dynamics Incompressible Flow Thermal Effects Thermal Conduction Linear Elasticity Detonation

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Flapping-Wing Fluid-structural Interaction Analysis Using Corotational Triangular Planar structural Element

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AIAA JOURNAL 2016年第8期54卷 2265-2276页

作者： Cho, Haeseong Kwak, JunYoung Shin, SangJoon Lee, NamHun Lee, SeungSoo Seoul Natl Univ Dept Mech & Aerosp Engn 1 Gwanak Ro Seoul 151744 South Korea Korea Aerosp Res Inst Rocket Engine Team Daejeon 16984 South Korea Seoul Natl Univ Dept Mech & Aerosp Engn Inst Adv Aerosp Technol 1 Gwanak Ro Seoul 151744 South Korea Inha Univ Dept Aerosp Engn Inchon 100 South Korea

In this paper, a triangular planar element is developed for a geometrically nonlinear structural analysis, which includes the drilling degrees of freedom using a corotational framework. Based on the assumptions of a small degree of strain and large displacement, the corotational framework allows an accurate geometrically nonlinear structural analysis. The presently improved corotational framework accommodates in-plane rotational behavior ( that is, the drilling degrees of freedom) by using the corotational framework corresponding to a solidlike planar element. It focuses on triangular planar elements that will be useful for three-dimensional analysis using a reduced number of degrees while targeting a structure with a complex geometry, such as a flapping wing. Regarding the present analysis, validation by solving both static and time-transient problems is conducted. The fluid-structure interaction framework is then developed by using the present structural analysis. During this validation procedure, the present results are compared with those obtained with three-dimensional solid elements provided by the commercial software ANSYS. Finally, a relevant fluid-structure interaction analysis for the flapping wing is conducted and an examination of the usefulness of the present planar element is done through comparisons between experimental results and those obtained in earlier studies.

关键词： structural Analysis Flexible Wings FSI Nastran Two Dimensional Elements CFD Analysis computational structural dynamics High Aspect Ratio Freestream Conditions Kinetic Energy

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Time-Dependent Aeroelastic Adjoint-Based Aerodynamic Shape Optimization of Helicopter Rotors in Forward Flight

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AIAA JOURNAL 2016年第12期54卷 3813-3827页

作者： Mishra, Asitav Mavriplis, Dimitri Sitaraman, Jay Univ Michigan Dept Aerosp Engn Ann Arbor MI 48109 USA Univ Wyoming Dept Mech Engn Laramie WY 82071 USA Parallel Geometr Algorithms LLC Sunnyvale CA 94087 USA

A formulation for sensitivity analysis of fully coupled time-dependent aeroelastic rotors in forward flight with trim constraints is given in this paper. The formulation includes the effect of blade shape parameters as well as blade cyclic pitch control parameters to enable analysis and optimization of rotors in a trimmed condition. Both forward sensitivity and adjoint sensitivity formulations are derived that correspond to analogs of the nonlinear aeroelastic analysis problem. Both sensitivity analysis formulations make use of the same iterative disciplinary solution techniques used for analysis, and they make use of an analogous coupling strategy. The fully coupled aeroelastic analysis formulation is first verified to effectively perform performance predictions of a four-bladed rotor in forward flight started impulsively from rest. Upon successful verification of the fully coupled adjoint formulation, it is used to perform trim and aerodynamic shape design optimization for helicopter rotors in forward-flight conditions.

关键词： Helicopter Rotor Aerodynamic Shape Optimization Sensitivity Analysis Aeroelastic Analysis CFD Simulation FSI structural Modeling Arbitrary Lagrangian Eulerian computational structural dynamics Shape Optimization

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Aerodynamic and structural Studies of a Flapping Wing in Forward Flight

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AIAA JOURNAL 2016年第9期54卷 2768-2781页

作者： Demasi, Luciano Santarpia, Enrico Dipace, Antonio Cavallaro, Rauno Gordnier, Raymond E. San Diego State Univ Dept Aerosp Engn San Diego CA 92182 USA Air Force Res Lab Aerosp Syst Directorate Aerodynam Technol Branch Wright Patterson AFB OH 45433 USA Univ Calif San Diego Dept Struct Engn San Diego CA 92103 USA San Diego State Univ Computat Sci Res Ctr San Diego CA 92182 USA Univ Pisa Dipartimento Ingn Aerosp Pisa Italy

Flapping flight is commonly seen in nature at low Reynolds numbers. This work investigates the physical aspects of forward flight for flapping unmanned aerial systems. The kinematics discussed in this paper is based on an anticlockwise figure-8-shaped flapping cycle. The evolution of the complex, unsteady vortical flow system that develops during the flapping motion is presented. Mechanisms for generating the lift and thrust are discussed, with emphasis on the unsteadiness of the flow features during both the downstroke and upstroke phases. A one-way fluid-structure interaction has been investigated, and the relative importance of aerodynamic forces is compared with respect to the inertial forces. The inhomogeneity of the wing in terms of mass distribution is studied, and it is shown that a higher density at the wing root is beneficial in respect to the mechanical power required to achieve the forward flight. Limited benefit is observed when higher material density at the leading edge is adopted.

关键词： Flapping Frequency Freestream Velocity Wing Root Unmanned Aerial Systems Fluid Structure Interaction Vortex Structure Aerodynamic Angle Large Eddy Simulation Pressure Coefficient computational structural dynamics

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Numerical simulation of structural dynamics using a high-order compact finite-difference scheme

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APPLIED MATHEMATICAL MODELLING 2016年第3期40卷 2431-2453页

作者： Hejranfar, Kazem Parseh, Kaveh Sharif Univ Technol Dept Aerosp Engn Tehran Iran

A high-order compact finite-difference scheme is applied and assessed for the numerical simulation of structural dynamics. The two-dimensional elastic stress-strain equations are considered in the generalized curvilinear coordinates and the spatial derivatives in the resulting equations are discretized by a fourth-order compact finite-difference scheme. For the time integration, an implicit second-order dual time-stepping method is utilized in which a fourth order Runge-Kutta scheme is used to integrate in the pseudo-time level. The accuracy and robustness of the solution procedure proposed are investigated through simulating different two-dimensional benchmark test cases in structural dynamics. A sensitivity study is also performed to examine the effect of the grid size on the accuracy and performance of the solution. The numerical results obtained by implementing the high-order compact finite-difference scheme are compared with the analytical solutions as well as the available numerical results which exhibit good agreement. The present work represents the first known implementation of the high-order compact finite-difference scheme in computational structural dynamics and that the solution methodology proposed is robust, accurate and efficient for such simulations. Note that the numerical solution procedure proposed to achieve high accurate results is simpler than the high-order finite-volume and finite-element formulations. The results obtained by applying the high-order compact finite-difference scheme can be considered as benchmark solutions for the assessment of the accuracy of other numerical methods applied for the simulation of structural dynamics problems. (C) 2015 Elsevier Inc. All rights reserved.

关键词： computational structural dynamics Elastic stress-strain equations Compact finite-difference scheme High accuracy solutions

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Force Analysis of IPMC Actuated Fin and Wing Assembly of a Micro Scanning Device through Two-way Fluid Structure Interaction Approach

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INTERNATIONAL JOURNAL OF ENGINEERING RESEARCH IN AFRICA 2016年 21卷 19-32页

作者： Ul Haq, Mazhar Gang, Zhao Sun, Zhuang-Zhi Aftab, S. M. Harbin Engn Univ Dept Mech & Elect Engn Harbin 150001 Heilongjiang Peoples R China

In this paper, a methodology is presented to perform force analysis of wing and fin assembly of a micro fish like device through strongly coupled two-way fluid structure interaction approach. The scanning device operates underwater and is towed by a surface vessel through a tow cable. Device fins are actuated by ionic polymer metal composite (IPMC) actuators, an EAP actuator. Fins act as riser, depressor and stabiliser against roll motion of the device. During tow, wing and fin assembly of the device come under hydrodynamic forces. These forces are influenced by fin displacement under IPMC actuation and wing's angle of attack for same towing conditions. The interaction of wing and fin assembly with the fluid must be considered, through fluid structure interaction (FSI) analysis, to appraise its performance as depressor, riser and stabilizer against hydrodynamic forces. To obtain an accurate prediction to the hydrodynamic forces on wing and fin assembly of the device, it is necessary to conduct dynamic analysis of the surrounding fluid by computational fluid dynamics (CFD). A numerical simulation of three dimensional model of the assembly is performed in ANSYS WORKBENCH by coupling transient structural and Fluid Flow (CFX) analysis systems. The lift and drag forces acting on wing, along with their corresponding coefficients, are also quantified and the influence of wing's angle of attack and fin displacement, on generation of these forces, has also been revealed. The presented methodology is also applicable to self-propelled micro robots.

关键词： Numerical simulation Fluid structure interaction Ionic polymer metal composite computational structural dynamics computational fluid dynamics

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