IMPLEMENTATION OF SEMI-EMPIRICAL MODELS TO ENHANCE THE ACCURACY OF PANEL METHODS FOR DRAG PREDICTION AT SUPERSONIC SPEEDS

Abstract

This paper introduces an attempt to enhance the accuracy of panel methods. A low-order panel method is selected and coupled with semi-empirical methods to enhance the accuracy of drag prediction of flying bodies at supersonic speeds. The semi-empirical methods are used to improve the accuracy of drag prediction by mathematical modelling of viscosity, base drag, and drag due to wing-body interference. Both methods were implemented by a computer program and validated against experimental and analytical results. The comparisons show that a considerable improvement has been achieved for the selected panel method for prediction of drag coefficients. In general, accuracy within an average value of -4.4% was obtained for the enhanced panel method. Such accuracy could be considered acceptable for the preliminary design stages of supersonic flying bodies such as projectiles and missiles. The developed computer program gives satisfactory results as long as the considered configurations are slender and the angles of attack are small (below stall angle).

 ABSTRAK: Kertas kerja ini memperkenalkan percubaan untuk  mempertingkatkan ketepatan kaedah panel. Kaedah panel tertib rendah telah dipilih dan digabungkan dengan kaedah separa empirik untuk mempertingkatkan ketepatan ramalan seret objek terbang pada kelajuan supersonik. Kaedah semi empirikal yang digunakan untuk meningkatkan ketepatan jangkaan seret menggunakan model matematik bagi kelikatan, seretan dasar, dan  seretan disebabkan  oleh badan sayap interferens. Kedua-dua kaedah dijalankan menggunakan program komputer dan disah berdasarkan keputusan uji kaji dan analisis. Perbandingan keputusan menunjukkan peningkatan yang mendadak diperolehi melalui kaedah panel yang telah dipilih sebagai jangkaan pekali seret. Secara umumnya, ketepatan yang melingkungi nilai purata sebanyak -4.4% telah diperolehi daripada kaedah peningkatan panel. Keputusan sebegini boleh diterima untuk peringkat reka bentuk permulaan bagi objek terbang supersonik seperti projektil dan misil. Program komputer yang direka memberikan keputusan yang memuaskan selagi konfigurasi yang dipilih adalah kecil dan sudut serangan adalah rendah (di bawah sudut tegun).