Impact of Different UHBR-Engine Positions on the Aerodynamics of a High-Lift Wing

Abstract

To meet the demands of society and air transport regarding more efficient transport aircraft [1], improvement of the aerodynamic performance of high-lift systems during take-off and landing is of importance. Novel closely coupled Ultra-High-Bypass-Ratio-Engines (UHBR) are equipped with a geared fan which enables to achieve a lower noise emission and to maximize propulsion-efficiency. However, the flow around these engines differs from existing engines which has a strong impact on the achievable high-lift performance and stall behavior. The integration of these modern UHBR-engines into transport aircraft configurations is therefore an aerodynamic research topic that promises to be a major contribution in reaching the claimed goals. The DLR Institute of Aerodynamics and Flow Technology is currently investigating these integration effects in the sub-project MOVE.ON-LEDCCEN of the Luftfahrtforschungsprogramm IV-4 funded by the BMWi [3]. In this project different engine positions on a high-lift wing were investigated in a numerical study using RANS-CFD for several angle of attack settings. The extent of the leading edge devices was adjusted with the horizontal and the streamwise engine position through an integrated design. Thus, the maximum possible slat-length and the minimum required free cross-section between inboard- and outboard-slat were obtained for all engine positions. The investigation was conducted with a generic swept untapered wing based on the DLR-F15 airfoil in landing configuration [10] that depicts, together with a generic UHBR-engine with take-off thrust rating, a go-around flight attitude. The results of the study to be presented focus on the effects of the engine position on achievable maximum lift coefficient and on lift-to-drag ratio to identify an optimal engine position related to high-lift performance.