Research On Circulation Control Parameters Of Cylindrical Tail Boom

NOTAR changed the conventional concept of helicopter tail rotor. This technology adopts a tail boom with circulation control to balance the rotor anti-torque for cancelling the tail rotor, which eliminates adverse effects of tail rotor on helicopters. The circulation control tail boom has a simple structure and good safety, which improves the reliability and maintainability and reduces vibrations and noises of helicopter. What's more, it improves the manipulation of helicopter, so it is especially suitable for light helicopters.This paper studied the parameters of circulation control cylinder, which was controlled by the wall jet flowing around it. The influence of the slots'geometric parameters such as position, size and number on aerodynamic characteristics of a circulation control tail boom was analyzed by using the FLUENT software, which focused on effects of momentum coefficient's and slots'geometric parameters on aerodynamic characteristics of the tail boom. The detailed work in this paper includes:First, a model of circulation control tail boom was established by using CATIA, and pre-treatment software of FLUENT, GAMBIT, was employed for meshing. A method for grid generation of flow field around the tail boom was presented.Second, the momentum source model was used to analyze the rotor downwash and its code was programmed in FLUENT. Aerodynamic characteristic of the circulation control tail boom was studied. Wind tunnel and rotor downwash flow field were simulated and analyzed respectively. Influence of the slots'geometric parameters such as position, size and number on aerodynamic characteristics of the tail boom was analyzed according to the flow field data. The law that aerodynamic characteristics of the tail boom changing with the momentum coefficient and the slots'geometric parameters was obtained and the best parameters were chosen.Third, the above CFD analysis results were compared with experimental data and the theoretical model of circulation control tail boom was revised. In the end, an analysis model for engineering practice was established to provide theoretical guidance for a following experimental study.The results show that the slots position and momentum coefficient have marked influences on aerodynamic performance of the tail boom. Using double-slit jets and a proper momentum coefficient can help to increases the maximum lift coefficient of circulation control tail boom, and also can reduce the jet energy consumption.