No abstract

The Profilscanner developed by PTB enables traceable roughness and profile measurement of high aspect ratio structures with diameters down to 50 μm. For the first time the inner surfaces of small sonic nozzles with diameters in the submillimetre range could be successfully characterized. The comparison between these topographical measurements and corresponding mass flow rate experiments confirms the assumption that the topography of the inner surfaces has a strong influence on the mass flow rate of small nozzles.

Active high-lift systems of future civil aircraft allow noise reduction and the use of shorter runways. Powering high-lift systems electrically have a strong impact on the design requirements for the electrical power supply of the aircraft. The active high-lift system of the reference aircraft design considered in this paper consists of a flexible leading-edge device together with a combination of boundary-layer suction and Coanda-jet blowing. Electrically driven compressors distributed along the aircraft wings provide the required mass flow of pressurized air. Their additional loads significantly increase the electric power demand during takeoff and landing, which is commonly provided by electric generators attached to the aircraft engines. The focus of the present study is a feasibility assessment of alternative electric power supply concepts to unburden or eliminate the generator coupled to the aircraft engine. For this purpose, two different concepts using either fuel cells or batteries are outlined and evaluated in terms of weight, efficiency, and technology availability. The most promising, but least developed alternative to the engine-powered electric generator is the usage of fuel cells. The advantages are high power density and short refueling time, compared to the battery storage concept.

No abstract

Résumé. Le Profilscanner développé par le PTB permet de réaliser des mesures de rugosité et de de forme sur des structures d'un diamètre minimum de 40 µm présentant un rapport d'aspect élevé. Il a été possible pour la première de caractériser avec succès les surfaces internes de petites buses soniques d'un diamètre de l'ordre du micromètre. La comparaison entre ces mesures topographiques et des expériences correspondantes concernant le débit massique a confirmé l'hypothèse selon laquelle la topographie des surfaces internes a une forte influence sur le débit massique des microbuses.