هاشم مرادی

In recent years, the study of wing-body-tail interference has gained greater significance in aerodynamics because of its importance in the modern aircraft design. One of the interference consequences is formation of downwash phenomenon. Downwash reduces the wing’s effective angle of attack and as a result reduces lift force and also produces induced drag. Downwash changes the flow field downstream of the main wing and consequently changes the aerodynamic coefficients of the airplane’s tail. These changes directly affect the stability derivatives and control coefficients of an airplane. Because of the importance of the effects of the rate of downwash on the stability derivatives of an airplane, a three-dimensional airplane with T-shape tail in incompressible and compressible subsonic flows was studied numerically in this paper. A fully structured grid was used for the whole domain around the airplane. Aerodynamic coefficients of the horizontal tail of the airplane and also the downwash and downwash rate with respect to the angle of attack of the horizontal tail were investigated. In addition, the compressibility effects on the downwash rate of the airplane’s tail were also studied in this paper.