scholarly journals Advanced Ducted Engines: Impact of Unsteady Aerodynamics on Fan Vibration Properties

1992 ◽  
Author(s):  
Arno H. Klose
Keyword(s):  
Mode Coupling ◽  
Unsteady Aerodynamics ◽  
Light Weight ◽  
Aeroelastic Stability ◽  
Resonant Frequencies ◽  
Aerodynamic Loads ◽  
Reinforced Plastics ◽  
Unsteady Aerodynamic ◽  
Vibration Properties ◽  
Carbon Fibre Reinforced Plastics

Fans of Advanced Ducted Engines (ADE) will be built from light-weight materials such as carbon-fibre-reinforced plastics (CFRP). Due to their low density, the aeroelastic behaviour of these fan blades is significantly different from that of conventional titanium fan blading. Calculations performed during the design of ADE fan bladings show that self-induced aerodynamic loads can significantly alter the resonant frequencies; furthermore, aerodynamic coupling of the different in-vacuo eigenmodes can occur. This is not the case for conventional titanium fan blading, where the vibration properties are largely unaffected by unsteady aerodynamic forces. It is concluded that for light-weight fan blading, it is necessary to take into account aerodynamic stiffening and aerodynamic mode coupling when computing eigenfrequencies and aeroelastic stability.

Numerical Simulation of Unsteady Aerodynamic Loads over an Aircraft

2014 ◽  
Vol 908 ◽  
pp. 264-268
Author(s):  
Xiao Jun Xiang ◽  
Yu Qian
Keyword(s):  
Mach Number ◽  
Euler Equations ◽  
Unsteady Aerodynamics ◽  
Periodic Motions ◽  
Aerodynamic Loads ◽  
Unsteady Aerodynamic ◽  
Sinusoidal Motion ◽  
A Cell ◽  
Rigid Body Motions ◽  
Volume Method

The unsteady aerodynamic loads are the basic of the aeroelastic. This paper focuses on the computation of the unsteady aerodynamic loads for forced periodic motions under different Mach numbers. The flow is modeled using the Euler equations and an unsteady time-domain solver is used for the computation of aerodynamic loads for forced periodic motions. The Euler equations are discretized on curvilinear multi-block body conforming girds using a cell-centred finite volume method. The implicit dual-time method proposed by Jameson is used for time-accurate calculations. Rigid body motions were treated by moving the mesh rigidly in response to the applied sinusoidal motion. For an aircraft model, a validation of the unsteady aerodynamics loads is first considered. Furthermore, a study for understanding the influence of different Mach number was conducted. A reverse of the trend of hysteretic loops can be observed with the increasing of the Mach number.

Coupled analysis of the unsteady aerodynamics and multi-body dynamics of a small car overtaking a coach

2019 ◽  
Vol 233 (14) ◽  
pp. 3684-3699 ◽  
Author(s):  
Jun Liu ◽  
Zhengqi Gu ◽  
Taiming Huang ◽  
Shuya Li ◽  
Ledian Zheng ◽  
...  
Keyword(s):  
Adverse Effect ◽  
Unsteady Aerodynamics ◽  
Coupled Analysis ◽  
Detached Eddy Simulation ◽  
Aerodynamic Loads ◽  
Unsteady Aerodynamic ◽  
Eddy Simulation ◽  
Body Dynamics ◽  
Vehicle Motion ◽  
Multi Body

The severe additional aerodynamic loads that are generated on a small car when overtaking a coach have an adverse effect on the car handling stability and its safety. In this article, a two-way coupling of the unsteady aerodynamics and multi-body dynamics is performed in order to study the mutual interactions of a car in an overtaking maneuver with a coach. The unsteady aerodynamic interactions are obtained by using SST (Menter) K-Omega Detached Eddy Simulation and overset mesh technology. The aerodynamics couple the multi-body dynamics, taking into account the effects of the transverse spacing and the cross winds. To validate the necessity of the two-way coupling method, a one-way coupling of the aerodynamics to the vehicle motion is also conducted. Finally, by comparing the aerodynamic loads and the dynamic response of the overtaking car in different overtaking maneuvers between one- and two-way coupling, the results show that it should be considered with two-way coupling analyses of the car while overtaking a coach, particularly under the severe conditions of a lower transverse spacing or the crosswinds.

scholarly journals Effects of Structural Coupling on Mistuned Cascade Flutter and Response

1984 ◽  
Vol 106 (1) ◽  
pp. 17-24 ◽  
Author(s):  
R. E. Kielb ◽  
K. R. V. Kaza
Keyword(s):  
Coupled System ◽  
Aeroelastic Stability ◽  
Resonant Frequencies ◽  
Structural Coupling ◽  
Aerodynamic Loads ◽  
Natural Modes ◽  
Section Model ◽  
Cascade Flutter ◽  
The Stability ◽  
Two Degree Of Freedom

The effects of structural coupling on mistuned cascade flutter and response are analytically investigated using an extended typical section model. Previous work using two degree of freedom per blade typical section models has included only aerodynamic coupling. The present work extends this model to include both structural and aerodynamic coupling between the blades. The model assumes that the structurally coupled system natural modes have been determined and can be represented in the form of N bending and N torsional uncoupled modes for each blade, where N is the number of blades and, hence, is only valid for blade dominated motion. The aerodynamic loads are calculated by using two-dimensional unsteady cascade theories in the subsonic and supersonic flow regimes. The results show that the addition of structural coupling can affect both the aeroelastic stability and frequency. The stability is significantly affected only when the system is mistuned. The resonant frequencies can be significantly changed by structural coupling in both tuned and mistuned systems, however, the peak response is significantly affected only in the latter.

Numerical Simulation of Unsteady Aerodynamic Loads over an Aerofoil in Transonic Flow

2013 ◽  
Vol 644 ◽  
pp. 275-278 ◽  
Author(s):  
Yu Qian ◽  
Jun Li Yang ◽  
Xiao Jun Xiang ◽  
Ming Qiang Chen
Keyword(s):  
Mach Number ◽  
Euler Equations ◽  
Unsteady Aerodynamics ◽  
Angle Of Incidence ◽  
Periodic Motions ◽  
Aerodynamic Loads ◽  
Unsteady Aerodynamic ◽  
Reduced Frequency ◽  
Sinusoidal Motion ◽  
Naca 0012

The unsteady aerodynamic loads are the basic of the aeroelasitc. This paper focuses on the computation of the unsteady aerodynamic loads for forced periodic motions under high subsonic Mach numbers. The flow is modeled using the Euler equations and an unsteady time-domain solver is used for the computation of aerodynamic loads for forced periodic motions. The Euler equations are discretized on curvilinear multi-block body conforming girds using a cell-centred finite volume method. The implicit dual-time method proposed by Jameson is used for time-accurate calculations. Rigid body motions were treated by moving the mesh rigidly in response to the applied sinusoidal motion. For NACA 0012 airfoil, a validation of the unsteady aerodynamics loads is first considered. Furthermore, a study for understanding the influence of motion parameters, the Mach number, mean angle of incidence, reduced frequency, amplitude, was also conducted. A reverse of the trend of hysteretic loops can be observed with the increasing of the Mach number. Nonlinear hysteretic loops are turned up when increasing the amplitude and the reduced frequency during the applied pitch sinusoidal motion.

Applications of Variable-Axial Fibre Designs in Lightweight Fibre Reinforced Polymers

2015 ◽  
Vol 825-826 ◽  
pp. 757-762 ◽  
Author(s):  
Emanuel Richter ◽  
Axel Spickenheuer ◽  
Lars Bittrich ◽  
Kai Uhlig ◽  
Gert Heinrich
Keyword(s):  
Carbon Fibre ◽  
Design Strategies ◽  
Special Design ◽  
Reinforced Polymers ◽  
Reinforced Plastics ◽  
Strength And Stiffness ◽  
Carbon Fibre Reinforced Plastics

A load dependent and curvilinear respectively variable-axial fibre design can notably enhance the strength and stiffness of lightweight components compared to fibre reinforced structures made of common multiaxial fibre textiles. At the Leibniz-Institut für Polymerforschung Dresden e. V. (IPF) special design strategies are in the focus of current studies. Two currently developed components made of carbon fibre reinforced plastics, a lightweight three-legged stool and a lightweight recurve bow riser, are described within this paper.

Full-scale tests of unsteady aerodynamic loads and pressure distribution on fast trains in crosswinds

Measurement ◽  
2021 ◽  
Vol 186 ◽  
pp. 110152
Author(s):  
Hongrui Gao ◽  
Tanghong Liu ◽  
Houyu Gu ◽  
Zhiwei Jiang ◽  
Xiaoshuai Huo ◽  
...  
Keyword(s):  
Pressure Distribution ◽  
Full Scale ◽  
Aerodynamic Loads ◽  
Unsteady Aerodynamic ◽  
Full Scale Tests
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