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Abstract

When dealing with CFD simulations the turbulent nature is seen on most of the engineering flows and these flows need to be solved. Reliable and applicable CFD outputs can be obtained from the accurate modelling of the turbulence as it is one of the most vital elements of CFD modelling. The RANS equations are extensively employed to analyse the complex flows over aircraft and for this purpose, a turbulence model is needed for turbulent flow analyses. Compatible turbulence must be chosen for the exact predictions of aircraft aerodynamic characteristics. In this report, numerical analyses of Mini-UAV are done to compare the outputs of different types of turbulence models for the prediction of aircraft aerodynamic characteristics for various flight conditions i.e., -4° to 40° at Mach number 0.04. ANSYS software is employed for this aerodynamic analysis. The six turbulence models compared are the Spalart-Allmaras, k-ɛ standard, k-ɛ RNG, k-ɛ Realizable, k-ω standard, and k-ω SST model. The impact of several turbulence models on the Mini-UAV aerodynamic performance is also studied numerically and validated with existing experimental data from reliable sources. The lift and drag coefficients for both numerical and experimental results exhibit an excellent correlation at Mach number 0.04. The recorded maximum variation of the coefficient of lift and the lift-to-drag ratio is determined to be 9.43% at a stall angle of attack (38°) and 7.01% at a 4˚ angle of attack among the six various turbulence models. The summation of deviation of coefficients of lift and drag values i.e., 0.0166 for the Spalart-Allmaras turbulence model is found to be less compared with all the other turbulence models so it can be said that the Spalart-Allmaras turbulence model is the best fit in terms of coefficients of lift and drag for Mini-UAV applications for subsonic flow.

DOI

https://doi.org/10.15394/ijaaa.2021.1559

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