Research on Solving Algorithm and Accuracy for FADS-α Applied to the Vehicle with Blunt Fore-Bodies

Solving algorithm and accuracy for FADS-α applied to the vehicle with blunt fore-bodies were researched in this paper. For the typical 15° blunt fore-bodies, FADS operating in the flight envelope from Mach number 2.0 to 5.0 and α=－5°~30°, β=0° was considered. Firstly, the theoretical model based on a potential flow model and modified Newtonian flow theory was established, and the pressure port configuration for the FADS system applied to the vehicle with blunt fore-bodies was also determined. Secondly, the classical triple algorithm and modified triple algorithm, the linear five-hole probe algorithm, the non-linear five-port fitting method, the back propagation neural network modeling and the weighted least square algorithm were established respectively for FADS-α solving algorithm. Finally, the solving accuracy of different methods for FADS-α was compared systematically. The results show that the solving accuracy of classical triple algorithm, modified triple algorithm and weighted least square algorithm is similar, and all these three different methods can give good prediction for FADS-α. The neural network modeling can also give good prediction, but its algorithm architecture is determined by many empirical parameters. In addition, it also needs large qualities of training and testing data set. For the linear five-hole probe algorithm, its solving accuracy is similar to other methods for the range of small angle of attack. When the angle of attack is larger than 10°, solving accuracy becomes bad. Solving accuracy is good for nonlinear fitting algorithm, but the fitting process is quite complicated. Therefore, the methods based on the classical triple algorithm, the modified triple algorithm and the weighted least square algorithm are good choices for FADS-α applied to the vehicle with blunt fore-bodies.