Unsteady aerodynamic characteristics of a three-dimensional plate cascade in a subsonic gas flow

1995 ◽  
Vol 36 (2) ◽  
pp. 189-198
Author(s):  
V. P. Ryabchenko
Keyword(s):  
Gas Flow ◽  
Three Dimensional ◽  
Aerodynamic Characteristics ◽  
Unsteady Aerodynamic ◽  
Subsonic Gas Flow

scholarly journals Unsteady Aerodynamic Characteristics Simulations of Rotor Airfoil under Oscillating Freestream Velocity

2020 ◽  
Vol 10 (5) ◽  
pp. 1822
Author(s):  
Qing Wang ◽  
Qijun Zhao
Keyword(s):  
Three Dimensional ◽  
Grid Method ◽  
Leading Edge ◽  
Aerodynamic Characteristics ◽  
Critical Value ◽  
Dynamic Stall ◽  
Navier Stokes ◽  
Freestream Velocity ◽  
Unsteady Aerodynamic ◽  
Edge Vortex

The dynamic stall characteristics of rotor airfoil are researched by employing unsteady Reynolds-Averaged Navier-Stokes (RANS) method under oscillating freestream velocity conditions. In order to simulate the oscillating freestream velocity of airfoil under dynamic stall conditions, the moving-embedded grid method is employed to simulate the oscillating velocity. By comparing the simulated dynamic stall characteristics of two-dimensional airfoil and three-dimensional rotor, it is indicated that the dynamic stall characteristics of airfoil under oscillating freestream velocity reflect the actual dynamic stall characteristics of rotor airfoil in forward flight more accurately. By comparing the simulated results of OA209 airfoil under coupled freestream velocity/pitching oscillation conditions, it is indicated that the dynamic stall characteristics of airfoil associate with the critical value of Cp peaks (i.e., the dynamic stall characteristics of OA209 airfoil would be enhanced when the maximum negative pressure is larger than −1.08, and suppressed when this value is smaller than −1.08). By comparing the characteristics of vortices under different oscillating velocities, it indicates that the dissipation rate of leading edge vortex presents as exponent characteristics, and it is not sensitive to different oscillating velocities.

scholarly journals Flutter of Fan Blades in the Aircraft Engine in the Three-Dimensional Subsonic Gas Flow

2021 ◽  
pp. 13-21
Author(s):  
Vitaly Gnesin ◽  
Lyubov Kolodyazhnaya ◽  
Yuriy Bykov ◽  
Igor Kravchenko ◽  
Oleksii Petrov ◽  
...  
Keyword(s):  
Gas Flow ◽  
Operation Mode ◽  
Three Dimensional ◽  
Aircraft Engine ◽  
Three Dimensional Model ◽  
Blade Vibration ◽  
Blade Ring ◽  
Subsonic Gas Flow ◽  
The Given ◽  
Operational Development

Aeroelasticity problems arise in the different fields of technology. The accident-free operation of the airborne machines is one of the most important factors that should be taken into account during their designing and upgrading. The solution of this problem involves the implementation of many measures to provide the system reliability on the whole, including its individual elements, in particular aircraft engine, its fan whose wide-chord blades can be exposed to the wreckage due to different reasons including the aeroelastic effects, i.e. self-excited vibrations. As a result, the origination of the aeroelastic phenomenon (flutter) in design and off-design modes should be eliminated at the stage of the design and operational development of the rotor wheel that would result in a considerable increase of the level of reliability of the aircraft engine. Based on the analysis of the available methods used for the flutter prediction we can draw a conclusion that the most promising approach to the analysis of the aeroelastic behavior of the blade ring of fan is the use of the method based on the three-dimensional model of the aerodynamics and dynamics (the method used for the solution of the coupled aeroelastic problem). By solving the coupled aeroelastic problem of the nonstationary aerodynamics and elastic vibrations of the blades we can get the amplitude –frequency blade vibration spectrum for the three-dimensional gas flow, including forced vibrations and self-excided vibrations in order to increase the reliability of the blade row of turbine machines. The developed numerical method was used for the analysis of the aeroelastic behavior of the blade ring of the fan mounted in the airborne engine for the operation mode of 3520 rmp with appropriate boundary conditions at the inlet and outlet behind the ring. The computation data confirmed the origination of self-vibrations for the given fan operation mode.

scholarly journals Unsteady aerodynamic characteristics of a bionic flapping wing in three-dimensional composite motion

AIP Advances ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 015109
Author(s):  
Lun Li ◽  
Jiulong Xu ◽  
Yuan Gao ◽  
Jinghong Yang ◽  
Fan Bai ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Aerodynamic Characteristics ◽  
Flapping Wing ◽  
Unsteady Aerodynamic

scholarly journals Unsteady Aerodynamic Characteristics of Transversely Inclined Prisms Under Forced-Vibration---The Base Intensification Phenomenon

2021 ◽  
Author(s):  
Zengshun Chen ◽  
Jie Bai ◽  
Cruz Y. Li ◽  
Yemeng Xu ◽  
Jianmin Hua ◽  
...  
Keyword(s):  
Forced Vibration ◽  
Three Dimensional ◽  
Horseshoe Vortex ◽  
Aerodynamic Characteristics ◽  
Experimental Comparison ◽  
Force Coefficient ◽  
Aerodynamic Damping ◽  
Wind Speeds ◽  
Unsteady Aerodynamic ◽  
Inclination Angles

Abstract This work, through a series of forced-vibration wind tunnel experiments, investigates the aerodynamic characteristics of square prisms subject to the transverse inclination. An aeroelastic prism was tested under different wind speeds, inclination angles, and oscillation amplitudes. Through analysis on the mean pressure distribution, local force coefficient, force spectra, and aerodynamic damping coefficient, the unsteady aerodynamic characteristics of the configuration were revealed. Empirical observations discovered the Base Intensification phenomenon, which refers to a fundamental change in the structure’s aerodynamic behaviors given any degrees of transverse inclination. Specifically, it is the intensification of the aerodynamic loading, vortical activities, and aerodynamic damping on only the lower portion of an inclined structure. The phenomenon, being almost impactless to the upper portion, is also insensitive to changes in inclination angle and tip amplitude once triggered by the initial inclination. Analysis also revealed that the origin of Base Intensification phenomenon traces back to fix-end three-dimensional effects like the horseshoe vortex, instead of the predominant Bérnard-Kármán vortex shedding. Moreover, results showed that wind speed is the decisive factor for the structure’s crosswind motions. Inside the lock-in region, structure loadings, vortical activities, and the effects of Base Intensification are significantly amplified. Beyond the range, the configuration gradually resorts to a quasi-steady linearity. Finally, results from the force-vibration tests were used for the prediction of structure response. Experimental comparison revealed that the predictions notably outperform those based on rigid tests, forecasting the actual responses with a markedly improved accuracy.

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