Aerodynamic characteristics analysis of quadrangle inlet and exhaust grille for embedded ventilation cooling system of aircraft

Abstract

Adding grilles at the inlet and exhaust of the aircraft ventilation cooling system helps to improve the aerodynamic characteristics and electromagnetic shielding characteristics of the whole system. Taking the X-47B aircraft as the research object, the quadrilateral open inlet and exhaust ducts and their grilles of the ventilation and cooling system embedded in the fuselage are designed. Based on CFD method, the influence of four design parameters of intake and exhaust grille: diversion angle, grille thickness, aperture shape and aperture size on flow resistance characteristics of the pipeline system is analyzed. The results show that the flow resistance characteristics are better when the grille diversion angle of inlet and outlet is smaller and closer to the conventional inlet and outlet. For the inlet, the rectifier effect is better when the grille thickness is larger, and the outlet of the exhaust duct needs a suitable thickness of the grille to balance the rectification and exhaust resistance. Besides, the circular hole grille shows good effect in the inlet and exhaust port. The small flow rate of inlet needs to use small aperture grilles to increase the rectification effect and suppress the internal and external flow interference, while the small flow rate of exhaust channel uses large aperture grilles, and the large flow rate uses small aperture grilles to improve the mixing rectification efficiency of internal flow to external flow.

Keywords

• embedded ventilation cooling system
• inlet and exhaust
• grille
• computational fluid dynamics(cfd)