Publicação
Computational aerodynamic analysis of a wing with Prandtl’s bell-shaped lift distribution
| Resumo: | Efficient aerodynamic design is crucial for improving aircraft performance. The bell-shaped lift distribution (BSLD) wing design methodology proposed by Prandtl in 1933 is presented as a solution to achieve the minimum induced drag with the bending moment as the primary design constraint. This spanload is believed to increase wing efficiency by 11 percent when compared to its predecessor, elliptical lift distribution (ELD), while significantly enhancing controllability and eliminating the need for a vertical stabilizer. In 2016, NASA performed research on an experimental aircraft, designated as Prandtl-D, which incorporates Prandtl´s BSLD through nonlinear twist distributed along the wing.With the aim of numerically validating the BSLD theory, the present study takes advantage of the Computational Fluid Dynamics (CFD) software OpenFOAM® to simulate the flow around the Prandtl-D glider. The two-dimensional Reynolds-averaged Navier-Stokes (RANS) preliminary simulations over the aircraft’s airfoil validate the choice of the Spalart-Allmaras turbulence model for this analysis. Various aerodynamic parameters such as lift, drag, pitching moment and pressure coefficients are extracted across different angles of attack. The results obtained for the three-dimensional case are in agreement with published experimental testing and numerical studies. Furthermore, they demonstrate a strong correlation between the theoretical lift distribution and that derived from CFD simulations, thereby confirming the efficacy of BSLD in minimizing induced drag. An extensive analysis on stall and wingtip vortices also provides valuable insight into the increased controllability of the aircraft at high angles of attack. |
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| Autores principais: | Santos, Brian Estanqueiro |
| Assunto: | Bell-shaped lift distribution Induced Drag Prandtl-D Computational Fluid Dynamics OpenFOAM® Distribuição de sustentação em forma de sino Arrasto induzido Prandtl-D Dinâmica de Fluídos Computacional OpenFOAM® |
| Ano: | 2024 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade de Coimbra |
| Idioma: | inglês |
| Origem: | Estudo Geral - Universidade de Coimbra |
| Resumo: | Efficient aerodynamic design is crucial for improving aircraft performance. The bell-shaped lift distribution (BSLD) wing design methodology proposed by Prandtl in 1933 is presented as a solution to achieve the minimum induced drag with the bending moment as the primary design constraint. This spanload is believed to increase wing efficiency by 11 percent when compared to its predecessor, elliptical lift distribution (ELD), while significantly enhancing controllability and eliminating the need for a vertical stabilizer. In 2016, NASA performed research on an experimental aircraft, designated as Prandtl-D, which incorporates Prandtl´s BSLD through nonlinear twist distributed along the wing.With the aim of numerically validating the BSLD theory, the present study takes advantage of the Computational Fluid Dynamics (CFD) software OpenFOAM® to simulate the flow around the Prandtl-D glider. The two-dimensional Reynolds-averaged Navier-Stokes (RANS) preliminary simulations over the aircraft’s airfoil validate the choice of the Spalart-Allmaras turbulence model for this analysis. Various aerodynamic parameters such as lift, drag, pitching moment and pressure coefficients are extracted across different angles of attack. The results obtained for the three-dimensional case are in agreement with published experimental testing and numerical studies. Furthermore, they demonstrate a strong correlation between the theoretical lift distribution and that derived from CFD simulations, thereby confirming the efficacy of BSLD in minimizing induced drag. An extensive analysis on stall and wingtip vortices also provides valuable insight into the increased controllability of the aircraft at high angles of attack. |
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