NONLINEAR MATHEMATICAL MODELING OF TRANSONIC FLUTTER BY NONLINEAR DYNAMICS APPROACH

点击翻译按钮获取中文摘要

1. Flutter analysis based on Navier-Stokes code for a wing modelPreliminary analysis results conducted in 2001 has been reviewed and examined. The analytical results show that even though limit cycle oscillation (LCO) phenomena can be expressed specifying transonic flutter features, the results have some problems because an abrupt pressure change due to the enlarged part accommodating driving motors for control surfaces causes analytical difficulties. The follow-on analysis will be treated in the future program.2. Improvement of a nonlinear mathematical model for transonic flutter based on numerical analysisNonlinear terms are introduced in two modes making physical examination to nonlinear mathematical model derived in nonlinear dynamics approach. The bifurcation characteristics have been greatly improved accordingly to fit the wind tunnel test results. The results were presented at an international conference co-authored with a collaborative partner in Denmark (DTU). We discussed and … More confirmed the validity of mathematical modeling approach focusing the nonlinear relationship of generalized coordinates and the generalized aerodynamics.3. Refurbishing a wind tunnel test model and the results of transonic wind tunnel testsCracks at the part of the outer panel supporting a control surface and connecting ribs have been repaired. As the cooperation between the University of Fukui and the Japan Aerospace Exploration Agency, flutter experiment using a wing model at the agency's transonic wind tunnel has been carried out. In the tests bifurcation data have been obtained vibrating the wing model using its leading edge control surface as an exciter for the states with and without control. As a result, stability boundary and LCO have been successively confirmed in the test for controlled state. It is worldwide first time that LCO can happen at the dynamic pressure between the open loop and the closed loop flutter. Furthermore, for uncontrolled state at the subcritical dynamic pressure, a new phenomenon has been observed that the wing excited once staying in LCO then ceased flutter after removing the oscillation source. Less