AEROELASTIC PHENOMENA OF FLIGHT VEHICLES IN TRANSONIC REGION

2009 ◽  
Vol 23 (03) ◽  
pp. 421-424
Author(s):  
IN LEE ◽  
JONG-YUN KIM ◽  
KYUNG-SEOK KIM ◽  
IN-GYU LIM
Keyword(s):  
Structural Dynamics ◽  
Critical Problem ◽  
Flight Vehicles ◽  
Aeroelastic Analysis ◽  
Structural Nonlinearities ◽  
Computational Structural Dynamics ◽  
Computational Fluid Dynamics Cfd ◽  
Analysis System ◽  
Transonic Region ◽  
Coupled Techniques

Flight vehicles experience aeroelastic problems due to the interaction between structures and aerodynamic forces. Aeroelastic instability is usually a critical problem in transonic and lower supersonic regions. In present study, the aeroelastic analyses of several flight vehicles have been performed using the coupled techniques of computational fluid dynamics (CFD) and computational structural dynamics (CSD). The aeroelastic characteristics based on several aircraft models are investigated using the developed aeroelastic analysis system. On the other hand, structural nonlinearities always exist in flight vehicles. Structural nonlinearities such as freeplay and large deformation effects are considered in the present aeroelastic analysis system. Finally, aeroelastic characteristics of several flight vehicles will be explained considering both aerodynamic and structural nonlinearities.

Computational Fluid Dynamics–Computational Structural Dynamics Rotor Coupling Using an Unstructured Reynolds-Averaged Navier–Stokes Methodology

2012 ◽  
Vol 57 (1) ◽  
pp. 1-14 ◽  
Author(s):  
Jennifer N. Abras ◽  
C. Eric Lynch ◽  
Marilyn J. Smith
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Structural Dynamics ◽  
Flight Test ◽  
Navier Stokes ◽  
Structured Grid ◽  
Direct Contrast ◽  
Computational Structural Dynamics ◽  
Computational Fluid Dynamics Cfd ◽  
Grid Points

The focus of this paper is to discuss the unique challenges introduced through the use of unstructured grids in rotorcraft computational fluid dynamics (CFD)–computational structural dynamics (CSD) coupling. The use of unstructured grid methodology in CFD has been expanding because of the advantages in grid generation and modeling of complex configurations. However, the resulting amorphous distribution of the grid points on the rotor blade surface provides no information with regard to the orientation of the blade, in direct contrast to structured grid methodology that can take advantage of the ordered mapping of points to identify the orientation as well as simplifying airloads integration. A methodology has been developed and is described here, which now permits unstructured methods to be utilized for elastic rotary-wing simulations. This methodology is evaluated through comparison of the UH60A rotor with available flight test data for forward flight.

An Aero-Thermo-Elasticity Method Applied on the Supersonic Aircraft Model

2012 ◽  
Vol 215-216 ◽  
pp. 438-442 ◽  
Author(s):  
Hong Tang ◽  
Guo Guang Chen ◽  
Hui Zhu He
Keyword(s):  
Structural Dynamics ◽  
Thermal Deformation ◽  
Aircraft Design ◽  
Ride Quality ◽  
Supersonic Aircraft ◽  
Flutter Speed ◽  
Unsteady Aerodynamic ◽  
Aeroelastic Analysis ◽  
Computational Structural Dynamics ◽  
Analytical Tools

Coupling between the vibration frequencies and the unsteady aerodynamic will reduce the flutter speed and ride quality through the aerodynamic heat transfer. As the flight speed improved, the aeroelastic analysis has become an essential means of aircraft design. The method of aero-thermo-elastic (ATE) analysis is coupled with aircraft aeroelastic analysis and thermal deformation, and is more realistic reflection of the actual flight of the aircraft. In this paper, an ATE analysis of aircraft adopted by computational fluid dynamics/computational structural dynamics (CFD/CSD) methods, and compared with the traditional analysis, to provide analytical tools for the supersonic aircraft design.

Rotor Aeroelastic Stability Analysis Using Coupled Computational Fluid Dynamics/Computational Structural Dynamics

2011 ◽  
Vol 56 (4) ◽  
pp. 1-16 ◽  
Author(s):  
Hyeonsoo Yeo ◽  
Mark Potsdam ◽  
Robert A. Ormiston
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Structural Dynamics ◽  
Comprehensive Analysis ◽  
Operating Conditions ◽  
Aeroelastic Stability ◽  
Time Histories ◽  
Blade Tip ◽  
Computational Structural Dynamics ◽  
Analysis System

Computational fluid dynamics/computational structural dynamics (CFD/CSD) coupling was successfully applied to the rotor aeroelastic stability problem to calculate lead–lag regressing mode damping of a hingeless rotor in hover and forward flight. A direct time domain numerical integration of the equations in response to suitable excitation was solved using a tight CFD/CSD coupling. Two different excitation methods—swashplate cyclic pitch and blade tip lead–lag force excitations—were investigated to provide suitable blade transient responses. The free decay transient response time histories were postprocessed using the moving-block method to determine the damping as a function of the rotor operating conditions. Coupled CFD/CSD analysis results are compared with the experimentally measured stability data obtained for a 7.5-ft-diameter Mach-scale hingeless rotor model as well as stability predictions using the comprehensive analysis Rotorcraft Comprehensive Analysis System (RCAS). The coupled CFD/CSD predictions agreed more closely with the experimental lead–lag damping measurements than RCAS predictions based on conventional aerodynamic methods, better capturing key features in the damping trends.

scholarly journals High-Fidelity Fin–Actuator System Modeling and Aeroelastic Analysis Considering Friction Effect

2021 ◽  
Vol 11 (7) ◽  
pp. 3057
Author(s):  
Jin Lu ◽  
Zhigang Wu ◽  
Chao Yang
Keyword(s):  
System Modeling ◽  
Past Research ◽  
High Fidelity ◽  
Aeroelastic Stability ◽  
Aeroelastic Analysis ◽  
Structural Nonlinearities ◽  
Flutter Boundary ◽  
Actuator System ◽  
Friction Models ◽  
Comparison Of The Results

Both the dynamic characteristics and structural nonlinearities of an actuator will affect the flutter boundary of a fin–actuator system. The actuator models used in past research are not universal, the accuracy is difficult to guarantee, and the consideration of nonlinearity is not adequate. Based on modularization, a high-fidelity modeling method for an actuator is proposed in this paper. This model considers both freeplay and friction, which is easy to expand. It can be directly used to analyze actuator characteristics and perform aeroelastic analysis of fin–actuator systems. Friction can improve the aeroelastic stability, but the mechanism of its influence on the aeroelastic characteristics of the system has not been reported. In this paper, the LuGre model, which can better reflect the friction characteristics, was integrated into the actuator. The influence of the initial condition, freeplay, and friction on the aeroelastic characteristics of the system was analyzed. The comparison of the results with the previous research shows that oversimplified friction models are not accurate enough to reflect the mechanism of friction’s influence. By changing the loads, material, and geometry of contact surfaces, flutter can be effectively suppressed, and the power loss caused by friction can be minimized.

Optimization of Biomimetic Propulsive Kinematics of a Flexible Foil Using Integrated Computational Fluid Dynamics–Computational Structural Dynamics Simulations

2018 ◽  
Vol 141 (6) ◽  
Author(s):  
Jiho You ◽  
Jinmo Lee ◽  
Seungpyo Hong ◽  
Donghyun You
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Young’S Modulus ◽  
Phase Angle ◽  
Structural Dynamics ◽  
Stokes Equations ◽  
Young's Modulus ◽  
Immersed Boundary ◽  
Computational Structural Dynamics ◽  
Dynamics Simulations

A computational methodology, which combines a computational fluid dynamics (CFD) technique and a computational structural dynamics (CSD) technique, is employed to design a deformable foil whose kinematics is inspired by the propulsive motion of the fin or the tail of a fish or a cetacean. The unsteady incompressible Navier–Stokes equations are solved using a second-order accurate finite difference method and an immersed-boundary method to effectively impose boundary conditions on complex moving boundaries. A finite element-based structural dynamics solver is employed to compute the deformation of the foil due to interaction with fluid. The integrated CFD–CSD simulation capability is coupled with a surrogate management framework (SMF) for nongradient-based multivariable optimization in order to optimize flapping kinematics and flexibility of the foil. The flapping kinematics is manipulated for a rigid nondeforming foil through the pitching amplitude and the phase angle between heaving and pitching motions. The flexibility is additionally controlled for a flexible deforming foil through the selection of material with a range of Young's modulus. A parametric analysis with respect to pitching amplitude, phase angle, and Young's modulus on propulsion efficiency is presented at Reynolds number of 1100 for the NACA 0012 airfoil.

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