This paper introduces a semi-empirical model to predict the downwash gradient at the horizontal tail of a three-lifting-surface aircraft.The superposition principle applied to well established formulations valid for t...This paper introduces a semi-empirical model to predict the downwash gradient at the horizontal tail of a three-lifting-surface aircraft.The superposition principle applied to well established formulations valid for two lifting surfaces is not a reasonable approach to calculate the downwash of a canard-wing-tail layout,and this paper demonstrates that such a basic technique leads to incorrect results.Therefore,an ad hoc prediction model is proposed that considers the combined nonlinear effects of canard and main wing inductions on tail downwash,being based on a full factorial design sweep of CFD simulations obtained by varying the main geometrical parameters of the three lifting surfaces.A suitable analytical formula for the downwash gradient is established through a process of data analysis and factor extraction.The presented model extends the validity of the available models for traditional two-lifting-surface designs by means of a correction factor.The engineering estimation method introduced here exhibits an acceptable accuracy,as well as relatively small prediction errors,and it is suitable for conceptual and preliminary studies of threesurface layouts.The value of this methodology is confirmed by the validation with the results of numerical and experimental investigations on a case study aircraft.展开更多
基金funded for the development of an innovative high-capacity regional turboprop platform by the IRON projectreceived funding from the Clean Sky 2 Joint Undertaking under the European Union's Horimpzon 2020 research and innovation program under Grant Agreement No.699715part of Clean Sky 2 REG-GAM 2018 project implemented on the H2020 program under GA 807089。
文摘This paper introduces a semi-empirical model to predict the downwash gradient at the horizontal tail of a three-lifting-surface aircraft.The superposition principle applied to well established formulations valid for two lifting surfaces is not a reasonable approach to calculate the downwash of a canard-wing-tail layout,and this paper demonstrates that such a basic technique leads to incorrect results.Therefore,an ad hoc prediction model is proposed that considers the combined nonlinear effects of canard and main wing inductions on tail downwash,being based on a full factorial design sweep of CFD simulations obtained by varying the main geometrical parameters of the three lifting surfaces.A suitable analytical formula for the downwash gradient is established through a process of data analysis and factor extraction.The presented model extends the validity of the available models for traditional two-lifting-surface designs by means of a correction factor.The engineering estimation method introduced here exhibits an acceptable accuracy,as well as relatively small prediction errors,and it is suitable for conceptual and preliminary studies of threesurface layouts.The value of this methodology is confirmed by the validation with the results of numerical and experimental investigations on a case study aircraft.
