Flutter of Rectangular Plate at Non-Zero Flow Yaw Angle

2021 ◽  
Author(s):  
Farrukh Abdukhakimov ◽  
Vasily Vedeneev
Keyword(s):  
Oscillation Mode ◽  
Single Mode ◽  
Plate Motion ◽  
Panel Flutter ◽  
Simply Supported ◽  
Aerodynamic Pressure ◽  
Coupled Mode ◽  
Unsteady Aerodynamic ◽  
Yaw Angle ◽  
Zero Flow

Abstract Panel flutter is a phenomenon of self-exciting vibrations of skin panels of flight vehicles moving at high speeds. There are two types of panel flutter. The first one is the coupled-mode flutter, which is caused by the interaction of two panel eigenmodes. The second type is the single-mode flutter, in this case the coalescence of eigenfrequencies and a significant change in the oscillation mode shape does not take place. The stability of the infinite series of thin elastic rectangular plates simply supported along all edges is investigated in this study. The non-zero flow yaw angle with supersonic leading edge is considered. We use potential flow theory to derive expression for the unsteady aerodynamic pressure distribution over the oscillating plate. The plate motion equation, after the substitution of expression for unsteady aerodynamic pressure, with simply supported boundary conditions, is an integro-differential eigenvalue problem for finding complex eigenvalues. We use the Bubnov–Galerkin procedure for finding eigenvalues. Thus, the flutter criterion is the sign of imaginary part of eigenvalue. Flutter boundaries for the first eigenfrequencies were computed for non-zero yaw angles We show how the single-mode and coupled-mode flutter boundaries are changed with the change of the yaw angle.

Nonlinear Multi-Modal Panel Flutter Oscillations at Low Supersonic Speeds

2014 ◽  
Author(s):  
Vasily Vedeneev ◽  
Anastasia Shishaeva ◽  
Konstantin Kuznetsov ◽  
Andrey Aksenov
Keyword(s):  
Numerical Simulation ◽  
Limit Cycle ◽  
Time Domain ◽  
Internal Resonance ◽  
Gas Flow ◽  
Single Mode ◽  
Panel Flutter ◽  
Limit Cycle Oscillations ◽  
Plate Deformation ◽  
Coupled Mode

In this paper aeroelastic instability of a plate in a gas flow is investigated by direct time-domain numerical simulation. Plate deformation and gas flow are simulated in solid and fluid codes, respectively, with direct coupling between these codes. A series of simulations under different parameters has been conducted. Three types of the plate response have been observed: stability, static divergence and flutter. Depending on Mach number, two types of flutter were detected: single mode flutter and coupled mode flutter. At M = 1.8, a good correlation between the present study and the piston theory for coupled mode flutter has been obtained. At lower M, from 1 to 1.6, single mode flutter in 1st, 2nd and higher modes has been observed. Amplitudes and frequencies of flutter limit cycle oscillations have been studied. It is shown that limit cycle oscillations can occur in form of pure one-mode oscillations, or include 1:2 internal resonance, when fluttering mode excites another mode. In the region of Mach numbers from 1.3 to 1.5, where several plate modes are simultaneously unstable, transition from periodic to quasi-chaotic flutter oscillations occurs.

scholarly journals Correlation and Power Distribution of Intercore Crosstalk Field Components of Polarization-Coupled Weakly Coupled Single-Mode Multicore Fibres

Photonics ◽  
2021 ◽  
Vol 8 (6) ◽  
pp. 191
Author(s):  
José A. P. Morgado ◽  
Adolfo V. T. Cartaxo
Keyword(s):  
Power Distribution ◽  
Communication Systems ◽  
Single Mode ◽  
Coupled Mode ◽  
Weakly Coupled ◽  
Wide Range ◽  
Optical Communication Systems ◽  
The Mean ◽  
Distribution Of Power ◽  
Linear Propagation

The correlation and power distribution of intercore crosstalk (ICXT) field components of weakly coupled multicore fibers (WC-MCFs) are important properties that determine the statistics of the ICXT and ultimately impact the performance of WC-MCF optical communication systems. Using intensive numerical simulation of the coupled mode equations describing ICXT of a single-mode WC-MCF with intracore birefringence and linear propagation, we assess the mean, correlation, and power distribution of the four ICXT field components of unmodulated polarization-coupled homogeneous and quasi-homogeneous WC-MCFs with a single interfering core in a wide range of birefringence conditions and power distribution among the field components at the interfering core input. It is shown that, for homogeneous and quasi-homogeneous WC-MCFs, zero mean uncorrelated ICXT field components with similar power levels are observed for birefringence correlation length and birefringence beat length in the ranges of 0.5m,10m and 0.1m,10m, respectively, regardless of the distribution of power between the four field components at the interfering core input.

Experimental observation of single mode panel flutter in supersonic gas flow

2010 ◽  
Vol 26 (5) ◽  
pp. 764-779 ◽  
Author(s):  
Vasily V. Vedeneev ◽  
Sergey V. Guvernyuk ◽  
Alexander F. Zubkov ◽  
Mikhail E. Kolotnikov
Keyword(s):  
Experimental Observation ◽  
Gas Flow ◽  
Single Mode ◽  
Panel Flutter ◽  
Supersonic Gas Flow

Analytical solution for the buckling of rectangular plates under uni-axial compression with variable thickness and elasticity modulus in the y-direction

2009 ◽  
Vol 224 (1) ◽  
pp. 33-41 ◽  
Author(s):  
M Saeidifar ◽  
S N Sadeghi ◽  
M R Saviz
Keyword(s):  
Differential Equation ◽  
Analytical Solution ◽  
Power Series ◽  
Boundary Conditions ◽  
Variable Thickness ◽  
Elasticity Modulus ◽  
Plate Motion ◽  
Transverse Displacement ◽  
Buckling Loads ◽  
Simply Supported

The present study introduces a highly accurate numerical calculation of buckling loads for an elastic rectangular plate with variable thickness, elasticity modulus, and density in one direction. The plate has two opposite edges ( x = 0 and a) simply supported and other edges ( y = 0 and b) with various boundary conditions including simply supported, clamped, free, and beam (elastically supported). In-plane normal stresses on two opposite simply supported edges ( x = 0 and a) are not limited to any predefined mathematical equation. By assuming the transverse displacement to vary as sin( mπ x/ a), the governing partial differential equation of plate motion will reduce to an ordinary differential equation in terms of y with variable coefficients, for which an analytical solution is obtained in the form of power series (Frobenius method). Applying the boundary conditions on ( y = 0 and b) yields the problem of finding eigenvalues of a fourth-order characteristic determinant. By retaining sufficient terms in power series, accurate buckling loads for different boundary conditions will be calculated. Finally, the numerical examples have been presented and, in some cases, compared to the relevant numerical results.

Single‐mode microdisk laser with two ports for heptagonal coupled mode lasing

2015 ◽  
Vol 51 (18) ◽  
pp. 1442-1443 ◽  
Author(s):  
Ling Xiu Zou ◽  
Yong Zhen Huang ◽  
Xiao Meng Lv ◽  
Xiu Wen Ma ◽  
Jin Long Xiao ◽  
...  
Keyword(s):  
Single Mode ◽  
Coupled Mode

Coupled-mode equations for two weakly guiding single-mode fibers

1986 ◽  
Vol 11 (5) ◽  
pp. 324 ◽  
Author(s):  
Amos Hardy ◽  
Sami Shakir ◽  
William Streifer
Keyword(s):  
Single Mode ◽  
Coupled Mode

scholarly journals Performance Enhancement in Multicore Fiber Using Trench Assisted Technique

2021 ◽  
Author(s):  
Salma Fatmia ◽  
Manimegalai CT ◽  
Sabitha Gauni ◽  
K. Kalimuthu
Keyword(s):  
Performance Enhancement ◽  
Single Mode ◽  
Design Parameters ◽  
Coupled Mode Theory ◽  
Coupled Mode ◽  
Bending Radius ◽  
Pitch Bending ◽  
Multicore Fiber ◽  
Core Pitch ◽  
Trench Width

Abstract Analysis of crosstalk in multicore fiber using trench assisted technique. To reduce the crosstalk between the cores in the fiber the coupled mode theory and coupled power theory are adopted for crosstalk estimation and considering different design parameters such as core pitch, bending radius and wavelength to optimize the crosstalk performance. The homogeneous fiber which works under single mode operation has been considered. The study of performance by varying the trench width is also analysed. Crosstalk variation in outer cores and center core of the fiber is studied. And the study of variation of crosstalk with 5 different core radius has been done. The numerical simulation results of crosstalk behavior over bending radius, wavelength and trench width is obtained.

Numerical Analysis of Single Mode Panel Flutter in a Viscous Gas Flow

2010 ◽  
Author(s):  
Vasily V. Vedeneev
Keyword(s):  
Numerical Analysis ◽  
Gas Flow ◽  
Single Mode ◽  
Panel Flutter ◽  
Viscous Gas ◽  
Analytical Results ◽  
Require Solution ◽  
Mach Numbers

In this paper single mode panel flutter, which occurs at low supersonic Mach numbers, is studied. Numerical analysis which does not require solution of coupled FSI problem has been conducted. Flutter boundaries obtained are compared with previously known analytical results.

scholarly journals Investigations on the Unsteady Aerodynamic Characteristics of a Horizontal-Axis Wind Turbine during Dynamic Yaw Processes

Energies ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 3124 ◽  
Author(s):  
Xiaodong Wang ◽  
Zhaoliang Ye ◽  
Shun Kang ◽  
Hui Hu
Keyword(s):  
Wind Turbine ◽  
Turbine Blades ◽  
Aerodynamic Characteristics ◽  
Azimuth Angle ◽  
Horizontal Axis ◽  
Navier Stokes ◽  
Horizontal Axis Wind Turbine ◽  
Structured Grid ◽  
Unsteady Aerodynamic ◽  
Yaw Angle

Wind turbines inevitably experience yawed flows, resulting in fluctuations of the angle of attack (AOA) of airfoils, which can considerably impact the aerodynamic characteristics of the turbine blades. In this paper, a horizontal-axis wind turbine (HAWT) was modeled using a structured grid with multiple blocks. Then, the aerodynamic characteristics of the wind turbine were investigated under static and dynamic yawed conditions using the Unsteady Reynolds Averaged Navier-Stokes (URANS) method. In addition, start-stop yawing rotations at two different velocities were studied. The results suggest that AOA fluctuation under yawing conditions is caused by two separate effects: blade advancing & retreating and upwind & downwind yawing. At a positive yaw angle, the blade advancing & retreating effect causes a maximum AOA at an azimuth angle of 0°. Moreover, the effect is more dominant in inboard airfoils compared to outboard airfoils. The upwind & downwind yawing effect occurs when the wind turbine experiences dynamic yawing motion. The effect increases the AOA when the blade is yawing upwind and vice versa. The phenomena become more dominant with the increase of yawing rate. The torque of the blade in the forward yawing condition is much higher than in backward yawing, owing to the reversal of the yaw velocity.

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