AEROELASTIC FLUTTER ANALYSIS OF SUPERSONIC WING WITH MULTIPLE EXTERNAL STORES

Abstract

ABSTRACT: Flutter may be considered to be one of the most dangerous aeroelastic failure phenomenon. The flutter characteristic differs for each aircraft type, and depends on the wing geometry as well as its operational region of subsonic, transonic or supersonic speeds. Prior to performing a flight flutter test, extensive numerical simulations and Ground Vibration Test should be conducted where the structural finite element modes and the experimentation results should be matched, otherwise the numerical simulation model must be rejected. In this paper, the analysis of simulation of a supersonic wing equipped with external missiles loaded on the wing is presented. The structural mode shapes at each generated frequency are also visually presented. The analysis is carried out using MSC Nastran FEM software. The wing flutter with the external stores was simulated at different altitudes. The result shows that the flutter velocity is sensitive to the flight altitude. For this reason, the flutter analysis is conducted also for a negative altitude. The negative altitude is obtained by considering the constant equivalent speed-Mach number rule at the flutter speed boundary as a requirement in standard regulation of transport aircraft. ABSTRAK: Salah satu fenomena kegagalan aeroelastik yang paling membahayakan adalah kipasan (flutter). Ciri-ciri kegagalan kipasan (flutter) adalah berbeza untuk setiap jenis pesawat bergantung pada geometri sayap dan regim operasi sama ada subsonik, transonik atau supersonik. Sebelum melakukan ujian penerbangan kipasan , simulasi berangka luas dan ujian getaran peringkat bawahan (darat) perlu dijalankan di mana struktur mod unsur terhingga dan keputusan eksperimen harus dipadankan, sebaliknya model simulasi berangka boleh ditolak. Dalam kertas kerja ini, simulasi sayap supersonik dilengkapi dengan beban luaran peluru berpandu di sayap telah dianalisis di daerah supersonik tinggi. Bentuk mod struktur pada setiap mod frekuensi yang dihasilkan juga dipersembahkan secara visual. Analisis ini dilakukan dengan menggunakan perisian “FEM” MSC Nastran. Kepakan sayap dengan kedai-kedai luar telah disimulasikan pada ketinggian yang berbeza. Hasil kajian menunjukkan bahawa halaju kipasan(flutter) sensitif terhadap ketinggian penerbangan. Atas sebab ini, analisis flutter dilakukan juga untuk ketinggian negatif. Ketinggian negatif diperoleh dengan mempertimbangkan tetap bersamaan kelajuan Mach beberapa peraturan pada kelajuan sempadan debar sebagai keperluan dalam peraturan piawaiaan pesawat pengangkutan. KEYWORDS: aeroelasticity; flutter; finite element method; external store; mode shape; supersonic wing