טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentNahom Jidovetski Tzlil
SubjectWind-Tunnel Study of the ARMA Flutter Prediction Method
DepartmentDepartment of Aerospace Engineering
Supervisor Professor Daniella Raveh


Abstract

Aeroelastic flutter is a destructive instability phenomenon for which dedicated flight test campaigns are considered compulsory according to airworthiness regulations. In these tests, the dynamic characteristics of the aeroelastic system are interpreted from measurements of the aircraft’s structural responses to external excitations. Over the years, several flutter identification and prediction techniques have been suggested in order to increase the efficiency of flutter flight tests and to enable better prediction of the flutter boundary. While most of the methods rely on external mechanical excitation accessories, the Autoregressive Moving-Average (ARMA) flutter prediction method attempts to identify the aeroelastic system based on the aircraft structural response to random air turbulence excitation. The study presents an experimental study of flutter prediction via ARMA system identification and the use of a linear stability parameter. The study investigates the application aspects of the methodology in a dedicated wind tunnel experiment. An elastic wing was designed and manufactured using rapid prototyping and tested in a subsonic wind tunnel all the way to flutter. Structural responses were recorded by accelerometers, strain gauges, and by fiber-optic sensors (measuring strains). The data was processed using signal processing techniques, such as filtering and averaging, and used for system identification and flutter prediction. The study focuses on the prediction characteristics and accuracy, method applicability with various dynamic data, and signal processing techniques. The study addresses practical aspects of the application of the method in a wind-tunnel test and supports the feasibility of using the ARMA method for flutter flight test.