Note on the Use of Two-Dimensional Compressible Flow Aerodynamic Coefficients in the Flutter Analysis of a Tapered Wing

1953 ◽  
Vol 20 (6) ◽  
pp. 434-435
Author(s):  
R. J. Werdes
Keyword(s):  
Compressible Flow ◽  
Two Dimensional ◽  
Aerodynamic Coefficients ◽  
Flutter Analysis

Nonlinear dynamics of a two dimensional airfoil with freeplay in an inviscid compressible flow

2000 ◽  
Vol 4 (2) ◽  
pp. 125-133 ◽  
Author(s):  
Zoran Dimitrijević ◽  
Guy Daniel Mortchéléwicz ◽  
Fabrice Poirion
Keyword(s):  
Nonlinear Dynamics ◽  
Compressible Flow ◽  
Two Dimensional ◽  
Inviscid Compressible Flow

Robust Flutter Analysis of an Airfoil with Flap Freeplay Uncertainty

2008 ◽  
Vol 33-37 ◽  
pp. 1247-1252 ◽  
Author(s):  
Zhi Chun Yang ◽  
Ying Song Gu
Keyword(s):  
Control Surface ◽  
Two Dimensional ◽  
Advanced Technique ◽  
Worst Case ◽  
Wing Model ◽  
Freeplay Nonlinearity ◽  
Flutter Analysis ◽  
Flutter Boundary ◽  
Nominal Parameter ◽  
Flutter Margin

Modern robust flutter method is an advanced technique for flutter margin estimation. It always gives the worst-case flutter speed with respect to potential modeling errors. Most literatures are focused on linear parameter uncertainty in mass, stiffness and damping parameters, etc. But the uncertainties of some structural nonlinear parameters, the freeplay in control surface for example, have not been taken into account. A robust flutter analysis approach in μ-framework with uncertain nonlinear operator is proposed in this study. Using describing function method the equivalent stiffness formulation is derived for a two dimensional wing model with freeplay nonlinearity in its flap rotating stiffness. The robust flutter margin is calculated for the two dimensional wing with flap freeplay uncertainty and the results are compared with that obtained with nominal parameter values. It is found that by considering the perturbation of freeplay parameter more conservative flutter boundary can be obtained, and the proposed method in μ-framework can be applied in flutter analysis with other types of concentrated nonlinearities.

scholarly journals Resonance Vibration of Mistuned Bladed Discs in Stationary Operations

1997 ◽  
Author(s):  
Romuald Rządkowski
Keyword(s):  
Numerical Model ◽  
Compressible Flow ◽  
Two Dimensional ◽  
Rotating System ◽  
Response Level ◽  
Stationary Response ◽  
The Real ◽  
Disc Model ◽  
Real Geometry ◽  
Airfoil Blades

A numerical model for the calculation of resonance stationary response of mistuned bladed disc is presented. The bladed disc model includes all important effects on a rotating system of the real geometry. The excitation forces were calculated by a code on the basis of two-dimensional compressible flow (to M < 0.8) for thin airfoil blades. The calculations presented in this paper show that centrifugal stress, and the values of excitation forces, play an important role in considering the influence of mistuning on the response level.

An Asymptotic Analysis of Mixing Loss

1995 ◽  
Vol 117 (3) ◽  
pp. 367-374 ◽  
Author(s):  
G. Fritsch ◽  
M. B. Giles
Keyword(s):  
Asymptotic Analysis ◽  
Compressible Flow ◽  
Control Volume ◽  
Physical Significance ◽  
Pressure Waves ◽  
Two Dimensional ◽  
Asymptotic Approach ◽  
Transonic Turbine ◽  
Steady Simulation ◽  
Interface Mixing

The objective of this paper is to establish, in a rigorous mathematical manner, a link between the dissipation of unsteadiness in a two-dimensional compressible flow and the resulting mixing loss. A novel asymptotic approach and a control-volume argument are central to the analysis. It represents the first work clearly identifying the separate contributions to the mixing loss from simultaneous linear disturbances, i.e., from unsteady entropy, vorticity, and pressure waves. The results of the analysis have important implications for numerical simulations of turbomachinery flows; the mixing loss at the stator/rotor interface in steady simulations and numerical smoothing are discussed in depth. For a transonic turbine, the entropy rise through the stage is compared for a steady and an unsteady viscous simulation. The larger interface mixing loss in the steady simulation is pointed out and its physical significance is discussed. The asymptotic approach is then applied to the first detailed analysis of interface mixing loss. Contributions from different wave types and wavelengths are quantified and discussed.

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