AWAHL will design a wing with its high-lift system for an advanced regional turbo-fan aircraft with optimal performance and efficiency. The wing will be designed with respect to the aerodynamic performance and constraints using in-house tools for CFD calculations and shape optimization. The design is carried out including optimization of the position of the pylon/nacelle. The aerodynamically optimal wing is used as input to design a wing using an MDO process accounting for weights, loads and aero-elastic effects in addition to the aerodynamics. The aero-elastic wing design will include minimization of the total structural wing weight based on CFD defined loads distributions at selected design points. The aerodynamically designed wing will be used as input to generate a high-lift configuration for the aircraft. The wing will be split up in a conventional 3-element configuration and the design carried out in 2D including sweep (2.5D). Alternative high-lift concepts may be investigated if required to reach aerodynamics targets. The design will be verified with RANS CFD calculations in 3D. The kinematic design of the deployment mechanisms to the high-lift configuration will be carried out as well.
The proposed technical work is divided in four work packages during 19 months following the task layout in the topic description. Each work package will be documented in separate deliverables and summarised in a separate additional deliverable. The maximum budget is estimated to 450,000 €. The consortium consists of three partners, the Swedish research organisation FOI being the coordinator, the Italian university POLIMI and the Belgian company ASCO. All three partners are highly capable, well established and active in national and European collaborative programs related to aerodynamic, aero-elastic and high-lift design and simulations.
The AWAHL (Advanced Wing And High Lift design) project comprises wing and high lift design of a regional turbo jet aircraft. It has been carried out within the Green Regional Aircraft (GRA) ITD of Clean Sky JU. AWAHL has three partners, FOI (Swedish Defence Research Agency) in Stockholm, the university Polimi in Milan and the company ASCO Industries in Belgium. The current periodic report covers the entire duration of the project which was 19 months after project extension.
The work is divided in four work packages (WPs) where the wing is first aerodynamically designed by in-house CFD and optimization tools in the first work package WP1 with optimal performance and constraints. The optimized wing is then used as input to WP2 in which an aeroelastic wing is designed minimizing the weight of the wing based on CFD defined loads distributions. The high lift design is carried out in WP3 which is closely connected to WP4 where the mechanical kinematic design is made to ensure its feasibility.
The design of the wing was eventually carried out in 3D using gradient based optimization. The performance of the wing was then evaluated with the wing attached to the fuselage and with the pylon/nacelle wit flow through conditions. The aerodynamic performance constrains were fulfilled at all design points leaving sufficient margin for additional losses due to tails, flap installations etc. The size of the wing was increased above specification, which was agreed in the project, so that a sufficient amount of fuel could be loaded into the wing. Due to this, some additional investigations were carried out on a down-scaled wing due to discussions about the size of the wing; the performance is still above required targets at the higher Mach numbers.
The optimized wing was then used for an aeroelastic design by optimization of the wingbox. Two different materials have been taken into account, aluminum alloy and carbon fiber composite; minimum weight is the objective of the aeroelastic optimization. Two structural models were used based on a stick model of the whole aircraft and on a detailed FEM model of the wing, respectively. Both strength and stability constraints have been included into the minimum weight Nastran optimization. The optimized structural weight of the wing is less than half with carbon fiber composite compared to the weight with aluminum. The performance was then evaluated by CFD investigations using the deformed wing. The higher the tip rotation, the worse becomes the aerodynamic performance.
A conventional three element high lift system with a forward slat and single slotted rear flap was developed from the designed wing in WP1. The design of the high lift configuration is carried out in 2.5D assuming infinite wing sweep with the leading edge sweep angle. The designs are then extended to a 3D wing, the performance of the high lift configurations are assessed from CFD calculations of the full 3D configurations including fuselage and pylon/nacelle. The performance was evaluated for both a landing and take-off configuration. The performance is acceptable but depending on which surface is used for the non-dimensional forces, the surface being either the specified surface or the actual surface of the enlarged wing. Due to kinematic constraints it was not possible to scale down the wing. Some attempts to improve the performance were made by adjusting the deflections of the flap and slat. The maximum lift increases about 12% indicating that the design in 2.5D is questionable for a wing with such a high sweep angle.
Several concepts for the kinematics of actuation of the slat and flap were investigated. For the slat, the only feasible and adequate alternative was the hydraulic actuation option due to the confined space at the leading edge. For the flap a ‘fixed rotating carriage’ concept was selected.