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Preliminary Design of Propeller-Driven Aircraft with Active High-Lift System
von Tayson William WeissAbstract
This thesis seeks to evaluate the influence of the aerodynamic consideration of a propeller engine on the solution of the preliminary design task for a propeller-driven aircraft with active high-lift provision. Therefore, an existing multidisciplinary aircraft design framework is extended towards the consideration of the aforementioned propulsion and high-lift technologies. The combination of both technologies promises a reduction of fuel consumption and emissions, as well as an improved utilization of existing airport capacities. The methodological extensions comprise the integration of a commercial aerodynamic panel method allowing for the representation of powered engines, as well as the development of methods for the prediction of maximum lift and blowing momentum expenditure of internally blown Coandă-flaps (IBF). The implementation of a panel model generation process allows for the explicit volumetric representation of an aircraft surface with engine nacelles and deployed high-lift devices. Maximum lift and blowing momentum expenditure are determined by relating the 3D-panel model to 2D-RANS airfoil data. Moreover, a variant of a finite element method and fully stressed design based approach to the estimation of structural masses is identified, allowing to find feasible and mass convergent structural designs. Two variants of the present aerodynamic model, i. e. without and with representation of the propeller, are compared to corresponding variants of a 3D-RANS reference model for the case of a propeller-driven aircraft with IBF high-lift system. Both models show satisfactory agreement in aerodynamic forces and moments under symmetric cruise and landing flight conditions without representation of the propeller and symmetric cruise flight conditions with representation of the propeller. For the assessed symmetric landing flight cases with representation of the propeller average deviations of 20% in lift are obtained. The maximum lift and blowing momentum coefficients predicted for the considered landing flight cases by both model variants show maximum magnitudes of deviation of 8.6% and 2%, respectively. The assessment of asymmetric flight cases by both model variants yields considerable deviations in lateral aerodynamic coefficients. Therefore, the analysis of critical flight cases for the evaluation of vertical tail plane and aileron sizes is conducted by handbook methods implemented prior to this thesis. The extended multidisciplinary design framework is used to solve the design task for several variants of a propeller-driven aircraft with IBF high-lift system. The design variants account for different engine positions, wing mounting angles and aileron widths. Each analysis is conducted without and with representation of the propeller in the aerodynamic panel model. The aerodynamic consideration of the propeller results for the considered designs in a decreased lift to drag ratio in cruise flight, increases in fuselage mass and maximum lift, as well as in reduced landing field lengths. Moreover, changes of −0.1% to +6% in operational empty weight, −0.2% to +5% in maximum takeoff weight and −2% to +7% in direct operating costs are obtained.
This thesis seeks to evaluate the influence of the aerodynamic consideration of a propeller engine on the solution of the preliminary design task for a propeller-driven aircraft with active high-lift provision. Therefore, an existing multidisciplinary aircraft design framework is extended towards the consideration of the aforementioned propulsion and high-lift technologies. The combination of both technologies promises a reduction of fuel consumption and emissions, as well as an improved utilization of existing airport capacities. The methodological extensions comprise the integration of a commercial aerodynamic panel method allowing for the representation of powered engines, as well as the development of methods for the prediction of maximum lift and blowing momentum expenditure of internally blown Coandă-flaps (IBF). The implementation of a panel model generation process allows for the explicit volumetric representation of an aircraft surface with engine nacelles and deployed high-lift devices. Maximum lift and blowing momentum expenditure are determined by relating the 3D-panel model to 2D-RANS airfoil data. Moreover, a variant of a finite element method and fully stressed design based approach to the estimation of structural masses is identified, allowing to find feasible and mass convergent structural designs. Two variants of the present aerodynamic model, i. e. without and with representation of the propeller, are compared to corresponding variants of a 3D-RANS reference model for the case of a propeller-driven aircraft with IBF high-lift system. Both models show satisfactory agreement in aerodynamic forces and moments under symmetric cruise and landing flight conditions without representation of the propeller and symmetric cruise flight conditions with representation of the propeller. For the assessed symmetric landing flight cases with representation of the propeller average deviations of 20% in lift are obtained. The maximum lift and blowing momentum coefficients predicted for the considered landing flight cases by both model variants show maximum magnitudes of deviation of 8.6% and 2%, respectively. The assessment of asymmetric flight cases by both model variants yields considerable deviations in lateral aerodynamic coefficients. Therefore, the analysis of critical flight cases for the evaluation of vertical tail plane and aileron sizes is conducted by handbook methods implemented prior to this thesis. The extended multidisciplinary design framework is used to solve the design task for several variants of a propeller-driven aircraft with IBF high-lift system. The design variants account for different engine positions, wing mounting angles and aileron widths. Each analysis is conducted without and with representation of the propeller in the aerodynamic panel model. The aerodynamic consideration of the propeller results for the considered designs in a decreased lift to drag ratio in cruise flight, increases in fuselage mass and maximum lift, as well as in reduced landing field lengths. Moreover, changes of −0.1% to +6% in operational empty weight, −0.2% to +5% in maximum takeoff weight and −2% to +7% in direct operating costs are obtained.