Accuracy Evaluation of Semi-empirical and Numerical Methods in Estimation of Aerodynamic Coefficients for air-launch-to-orbit delta wing

In this paper, the importance of accurate estimation of the aerodynamic performance of delta wing has been mentioned. Some available and conventional methods of estimating the aerodynamic coefficients composed of CFD methods and industrial and commercial software have been selected and for comparison, a wing similar to delta wing mounted on Pegasus Air-launch-to-orbit missile as a template is being selected. The reason for this selection, mainly is the lack of wind tunnel in design process and flying in a wide range of flow regimes. As many parameters may be utilized in design process such as the aerodynamic force and moment coefficients, stability derivatives, heat transfer coefficient and the structural loading parameters are being required. In this study, the accuracy of the results of different methods in estimating the force and moment coefficients, as the most significant quantities for performance analysis, at any flow regime has been checked and the suitable method has been introduced in terms of the flight condition. With respect to available parallel processing system, different CFD methods are compared together. Then validity of solution of Reynolds-averaged equations (RANS) and Euler method have been evaluated based on the comparison by DES solutions. Therefore, the valid intervals of the subsequent methods have been presented. Results are indicating the advantage of computational methods to industrial and semi-empirical software. Semi-empirical code and industrial software are shown satisfactory for computation in the linear range i.e. the small angle of attacks.