Structural concept of an adaptive shock control bump spoiler

Abstract

Drag reduction technologies in aircraft design are the key enabler for reducing emissions and for sustainable growth of commercial aviation. Laminar wing technologies promise a significant benefit by drag reduction and are, therefore, under investigation in various European projects. However, of the established moveable concepts and high-lift systems thus far most do not cope with the requirements for natural laminar flow wings. To this aim, new leading edge high-lift systems have been the focus of research activities in the last 5 years. Such leading edge devices investigated in projects include a laminar flow-compatible Kruger flap (Schlipf (2011) Insect shielding Krüger—structural design for a laminar flow wing. In: DGLR Congress 2011, Bremen, pp 55–60) and the Droop Nose concept (Kintscher et al. Ground testof an enhanced adaptive droop nose device. In: European Congress on Computational Methods in Applied Sciences and Engineering, ECCOMAS 2016. ECCOMAS2016—VII European Congress on Computational Methods in Applied Sciences and Engineering, 5–10 June 2016, Crete Island, Greece; Kintscher et al. Low speed wind tunnel test of a morphing leading edge. In: AIDAA—Italian Association of Aeronautics and Astronautics XXII Conference, 09–12 Sept. 2013. Neapel, Italien) and these can be considered as alternatives to the conventional slat. Hybrid laminar flow concepts are also under investigation at several research institutes in Europe (Fischer. Stepless and sustainable research for the aircraft of tomorrow—from AFloNext to Clean Sky 2. In: 1st AFloNext Workshop Key Note Lecture No. 1, Delft, The Netherlands, 10 Sept 2015). Another challenge associated with laminar wings aside from the development of leading edge movables is the need to address the control of aerodynamic shocks and buffeting as laminar wings are sensitive to high flow speeds. Here, one possible method of decreasing the wave drag caused by the aerodynamic shock is through the use of shock control bumps (SCBs). The objective of SCBs is the conversion of a single strong shock into several smaller and weaker λ-shocks resulting in a drag benefit when deployed correctly. A particular desirable characteristic of SCBs is that they should be adaptable in position and height as the shock position changes with varying conditions such as speed, altitude, and angle of attack during the flight. However, as a fixed case, SCBs can also help to control laminar buffeting by fixing the shock into given positions at the SCBs location. In this paper, a structural concept for an adaptive shock control bump spoiler is presented. Based on a concept of a fixed bump SCB spoiler, a design for an adaptive spoiler with two conventional actuators is presented. Design drivers and interdependencies of important design parameters are discussed. The presented design is simple and aims for a high TRL without adding much complexity to the spoiler. It is robust and able to form a bump with a height of 0.6% chord length which position can be adapted in a range of 10% chord. This paper is a follow-up of a previous publication (Kintscher and Monner, SAE Tech Paper 10.4271/2017-01-2164, 2017) with extending the focus by a validation of computational results by experimental tests.