Aviation

The current aircraft noise has a large contribution provenient from the airframe in which the most relevant sources are the landing gear, the flap and the slat. The leading edge slat is a distributed noise source since it spans almost the whole wing extension. The presence of excrescences inside the slat cove can change significantly the recirculating flow and the characteristics of noise generated. Previous experiments showed substantial increasing in the narrow band peaks for the MD30P30N high-lift model in which the slat geometry included a bulb seal attached at some positions of its...

Laminar separation bubbles present a three-dimensional self-excited instability mechanism which leads to the appearance of spanwise-periodic structures. In incompressible flow, this mechanism was found to become active at conditions in which wave-like, two-dimensional perturbations are only convectively unstable. In the absence of continuous external excitation, the three-dimensional instability is expected to dominate the flow dynamics and initiate the laminar-turbulent transition. This work extends previous analyses by incorporating the effect of compressibility at subsonic...

The authors study the relationship between aircraft cost and size for large commercial passenger jets. Based on a translog model, they develop an econometric cost function for aircraft operating cost and find that economies of aircraft size and stage length exist at the sample mean of their data set, and that for any given stage length there is an optimal size, which increases with stage length. The scale properties of the cost function are changed considerably if pilot unit cost is treated as endogenous, since it is correlated with size. The cost-minimising aircraft size is therefore...

This paper is about the allocation of tours of m targets to n vehicles. The motion of the vehicles satisfies a nonholonomic constraint (i.e., the yaw rate of the vehicle is bounded). Each target is to be visited by one and only one vehicle. Given a set of targets and the yaw rate constraints on the vehicles, the problem addressed in this paper is 1) to assign each vehicle a sequence of targets to visit, and 2) to find a feasible path for each vehicle that passes through the assigned targets with a requirement that the vehicle returns to its initial position. The heading angle at each...