Effects of Local Flow Variations on Landing Gear Noise Prediction and Analysis

This paper discusses a study on the local flows in the vicinity of aircraft landing gear. Local flows for various aircraft types at various operation conditions are extracted from a computational fluid dynamics database and analyzed to reveal parametric trends of the local flows. It is shown that, for wing-mounted gear, the circulation around the high-lift wing induces a flow under the wing in the opposite direction to the freestream flow and, hence, makes the local flow velocity lower than the freestream velocity. For fuselage-mounted gear, the trends are opposite; the local flow velocity for nose gear is usually slightly higher than the freestream. For all gear, it is shown that the local flow velocity is a decreasing function of the aircraft angle of attack. Based on these features, a simple reduced-order model is developed, which correlates the local flow velocity to the freestream velocity, the aircraft angle of attack, the maximum aircraft takeoff weight and the distance from the aircraft. All these parameters are readily available in practical applications, rendering the simple model suitable for landing gear noise prediction. Discussions are given on the effects of the local flow features on landing gear noise analysis and prediction with practical examples.