Aerodynamic Modelling of Unmanned Aerial System through Nonlinear Vortex Lattice Method, Computational Fluid Dynamics and Experimental Validation - Application to the UAS-S45 Bàlaam: Part 2.

This paper presents a comparison of a new non-linear formulation of the classical Vortex Lattice Method and a Computation Fluid Dynamics analysis in predicting the aerodynamic behaviour of an Unmanned Aerial System. The Computation Fluid Dynamics analysis used structured grid, for the airfoil, study and unstructured grid obtained from a grid convergence study, for the entire Unmanned Aerial System, that are needed to predict the aerodynamic coefficients. The Spalart-Allmaras and the k-ω models were used as turbulence models. The results have shown a close agreement between the methods presents and have indicated that the new formulation is adequate for aerodynamic model estimation.

Identification of corner separation modelling in axial compressor stage

The paper presents a study of corner separations in hub to blade region at various operation conditions towards compressor stall. It is known that for compressor flows with low or none separations computation fluid dynamics with RANS methods work quite well, however, for highly separated flows they are no longer entirely valid. Therefore, several criteria were applied for prediction and quantification of possible corner separation, and the main interest of this work is in predicting the separation just before it will actually happen by certain flow metrics, so these metrics can be further used as a ‘pre-stall’ criteria whilst the RANS CFD operating point still behave within its appropriate limits. Also the effect of shear lean is discussed in the presented context.

Semi-analytical and computational investigation of different fibrous structures affecting the performance of fibrous media

Three arrangement types of fibrous media have been established including “Mesh” (layered distribution), “Para” (unidirectional distribution), and “Nurbs” (random distribution), with fiber diameters ranging from 5 to 7 µm and solid volume fractions ranging from 14.58% to 21.95%. To describe the filtration performance, particles trajectories, and the influence of structural parameters of fibrous media, the computation fluid dynamics is adopted. The filtration efficiency and the pressure drop of fibrous media are calculated in computation fluid dynamics and semi-analytical model. It is found that the arrangement types have significant effects on the filtration efficiency and show the limitation of the semi-analytical model. With the Stokes number larger than 1, the numerical results and semi-analytical model have great consistency in the filtration efficiency for the “Mesh” and “Para” types than “Nurbs” type. Meanwhile, the pressure drop between the numerical results and the semi-analytical model is always consistent.