Abstract: An active effective flow-through area control system includes an upstream wall-flow perturber and a downstream wall-flow perturber situated in an inlet region of an aircraft engine. The downstream wall-flow perturber is positioned downstream from the upstream wall-flow perturber. The upstream and downstream wall-flow perturbers are configured to generate and trap at least one region of separated, vortical flow in the airflow through the inlet region. A method, for actively changing an effective flow-through area of an inlet region of an aircraft engine, includes creating at least one region of separated, vortical flow in an airflow passage defined by the inlet region. The method further includes trapping the region of separated, vortical flow in the airflow passage. The region of separated, vortical flow partially obstructs a main inlet airflow.

Abstract: A method of lasing a filler wire to weld a first workpiece to a second workpiece comprising first and second materials, respectively, includes positioning a tip of the filler wire above an opening defined by the workpieces. The tip extends over a width of the opening and over a portion of each of the workpieces. The filler wire is preheated and melted by directing a laser beam at the tip. The laser beam is advanced along a length of the opening with the tip positioned under the laser beam to form a high aspect ratio weld between the workpieces. The high aspect ratio weld has an aspect ratio of at least about two. The energy and time required for the laser beam to melt the filler wire is reduced as the filler wire is preheated.