鼓包唇口对边界层抽吸涵道风扇的性能影响及作用机理研究

The distributed fan propulsion aims to improve the aerodynamic performance of the aircraft and reduce fuel consumption. However, the ducted fan is continuously working under inflow distortion conditions caused by boundary layer ingestion, thus increasing aerodynamic loss and a decrease in the overall aerodynamic benefits gained by the aircraft. To control the aerodynamic loss in the boundary layer ingestion ducted fan, a loss reduction design strategy based on the lip-installed bump is developed. The influence of the flow control method on the performance and mechanism of the fan under the condition of boundary layer ingestion (BLI) is studied through numerical simulation. The research results show that compared with the original ducted fan, the bump will form a pressure distribution trend of high in the middle and low on both sides, and the low momentum fluid in the boundary layer will be moved to both sides of the bump. In this way, the bump accelerates the low-momentum fluids on the bottom of the lip and reduces the momentum loss thickness of the local boundary layer. Without losing the total pressure ratio, compared with the original ducted fan, the bump ducted fan effectively improved the distortion flow field of the intake lip, and the rotor domain inlet distortion index decreased by 9.7%. At the same time, due to the reduction of the distortion intensity at the bottom of the lip, the local load of the blade is also reduced, especially near the blade tip. Further, the decrease of the blade load near the tip leads to a reduction of the normal pressure difference between the pressure and suction surfaces which can eliminate the interaction between the tip leakage flow and the mainstream, resulting in a 1.16% decrease in the entropy loss of the blade tip in the distortion region. Under the condition of inflow distortion conditions, the adiabatic efficiency of off-design operation increased by 1.2%.