Abstract: The interference of the propeller slipstream on the aircraft components is one of the difficult points in aerodynamic design of turboprops. In the present study, the influence of propeller slipstream on wing, horizontal tail and vertical tail and its flow mechanism for a twin-engine turboprop regional airliner are investigated through numerical simulations. The computations are performed via the unsteady numerical method based on the dynamic patched grid. The calculated aerodynamic forces and surface pressure distributions agree well with the experimental data. The results indicate that under the influence of slipstream, the lift and drag of the whole plane have increased while the lift-drag ratio and the longitudinal static stability are reduced. What's more, the plane even suffers rolling and yawing moment in the non-sideslip condition. There are significant differences in the effect of slipstream on the separation of wing surfaces at different spanwise positions. On the downward side of the propeller, the flow separation is effectively suppressed because of the decreases in the local angle of attack caused by the swirl of the slipstream and a strong flow acceleration. However, on the upward side of the propeller, there is no significant improvement of the flow separation due to an increase in the local angle of attack and a slow flow speed. The slipstream has no effect on local dynamic pressure around the horizontal tail of the reference aircraft at low and moderate angles of attack, but it increases the downwash gradient, resulting in the reduction of the tail efficiency. The side force and the yawing moment of the vertical tail are caused by the sidewash of the slipstream which is closely related to the asymmetric wing-lift distribution.

Key words: turboprop aircraft, propeller slipstream, dynamic patched grid, unsteady numerical simulation, flow mechanism