Novel Morphing High-Lift Devices for Laminar Wing Design of Turboprop Aircraft Large-Scale Wind-Tunnel and CFD Assessment
Creators: name:  S. WALLIN 
name:   A. HANIFI 
name:   S. ADDEN 
name:   F. AMOROSO 
name:   F. BAGHERI 
Publisher: name: Proceedings of  the 9th European Conference for Aerospace Sciences. Lille, France, 27 June - 1 July, 2022
Year: 2022
Subjects: FLIGHT PHYSICS
COMPUTATIONAL AERODYNAMICS
EXPERIMENTAL AERODYNAMICS

description: Regional mobility in terms of air transportation is of fundamental importance for regional economic and social development by connecting countries, people and cultures. In this respect, novel turboprop designs will contribute to environmentally friendly and sustainable means of transportation. Turboprop configurations are efficient providing fuel savings of up to 20 percent with respect to equivalent technology turbofan aircrafts, and novel propeller design enables cruise speeds up to Mach 0.8. Moreover, additional drag reduction is achieved by utilizing natural laminar wing technology requiring smooth and continuous flow over the particularly shaped wing upper surface. The integration of turboprop engines into the airframe, and the design of high-lift devices for landing and take-off, presenting some unique aerodynamic challenges in particular when utilizing natural laminar flow wings for additional drag reduction. The Clean Sky 2 project WTM-RECYCLE, completed during 2021, supported the development and assessment of new and conceptual versatile aerodynamic high lift technologies as well as turboprop integration effects. Wind tunnel measurements of a 5m span large-scale turboprop aircraft model together with complementary CFD analyses were used to study the effect of morphing devices for drooped wing leading edge, geometry morphed flaps and winglets. Two different wing profile geometries in cruise, landing and take-off configurations were studied. Propeller installation effects were included by powered thrusting propellers in the wind-tunnel installation as well as in the CFD model. The large 5m span wind tunnel model of a complete aircraft with wing, fuselage, tail and running propeller engines was designed by IBK with a central wing core with hydraulic routing for the engines. The different wings, winglets and high-lift devices were made as interchangeable modules for rapid configuration changes within the wind tunnel enabled by highest precision manufacturing at Eurotech. Moreover, setting of control surfaces such as elevator, rudder, ailerons as well as inner and outer flaps were implemented. The model was instrumented with a 6DOF balance, flap balances and surface pressure taps. More than 300 lift/drag polars were measured at RUAG LWTE wind tunnel. Oil flow patterns of the separation onset over the wing and flaps were recorded for comparison with CFD. The CFD model was made by neptech with the same principle of interchangeable mesh modules of the different components, which are combined for all different configurations. Each mesh module is carefully designed with structure-like surface and boundary-layer meshes for best accuracy with wall-resolved RANS computations. The meshing process is accelerated by the scripting capabilities of Pointwise enabling automatic and modularized meshing for rapid turn-around times. The CFD solver M-Edge with the Spalart-Allmaras and Wallin-Johansson EARSM turbulence models was used by KTH with the model installed in the wind tunnel for comparison with measurements and for extrapolation to free flight. Moreover, transition predictions by a data-base method were made at KTH. The paper and presentation will show major results from the wind-tunnel campaign for the different configurations and control surface settings including thrusting engines. Moreover, CFD comparisons for wind-tunnel conditions and extrapolated to free flight will be presented. This project WTM-RECYCLE has received funding from the Clean Sky 2 Joint Undertaking under the European Unions Horizon 2020 research and innovation programme under grant agreement No 755605.