COMPUTATIONAL AND EXPERIMENTAL AERODYNAMIC ANALYSIS FOR THE WING OF A MINI UNMANNED AERIAL VEHICLE (UAV)

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1 COMPUTATIONAL AND EXPERIMENTAL AERODYNAMIC ANALYSIS FOR THE WING OF A MINI UNMANNED AERIAL VEHICLE (UAV) José Manuel Herrera Farfán Nohemí Silva Nuñez Hernán Darío Cerón Muñoz Nelson Javier Pedraza Betancourth

2 COMPANY OVERVIEW The Fundación Universitaria Los Libertadores is an institution of higher education and nonprofit public utility which has the mission to make professionals and critical citizens with broad sense of the social, ethical, aesthetic and political; research relevant, innovative and entrepreneurial spirit.

3 INGENIERIA AERONÁUTICA The Aeronautical Engineering program, educate competent professionals with strong ethics, humanistic and scientific basis; committed to their social environment, participants in the research and finding appropriate means to generate new opportunities in the aviation industry.

4 ESCOLA DE ENGENHARIA DE SÃO (EESC) The Escola de Engenharia de São Carlos (EESC) is one of the units of instruction, research and extension of the University of São Paulo (USP), which through its 10 undergraduate programs, including the Aeronautical Engineering course make highly qualified engineers to meet the demands of the labor market or continue their academic career.

5 The EESC is a national reference in the field of engineering and has contributed to the development of Brazilian society, implementation and dissemination of scientific, cultural and technological knowledge. Is also attentive to new global paradigms, it has established internationalization actions, with the completion of agreements with abroad institutions and implementing exchange programs.

6 PROBLEM DESCRIPTION The UAV-SOLVENDUS, aircraft its lack of aerodynamic analysis for the wing surface. Therefore it is necessary to rigorously design the wing of a mini-uav where the aerodynamic analysis is important to consider that the wing profile is selected from the mission for which it is designed.

7 METHODOLOGY MESH GENERATION Unstructured mesh it does not have a specific guidance in this cell line is much simpler but carries a higher computational cost; this type of mesh is used more irregular and complex geometries in which a structured mesh is very difficult to implement.

8 STRUCTURED MESH Is characterized by: all cells lines are regularly oriented in two or three directions. Algebraic methods: include using the values specified on the frontiers of the geometry to interpolate functions and generate curves within a domain; this is accomplished by interpolation through unidirectional Lagrange polynomials andhermes polynomials interpolations.

9 Não é possível exibir esta imagem no momento. CFD ANALISYS For this analysis, ANSYS, FLUENT was used in the modeling of airflow over the wing. The simulation was performed with atmospheric conditions of Sao Carlos, Brazil, where the experimental tests were performed. The next pictures, shows the aerodynamics lines for angles of the 4 and 10 respectively. It can be observed the presence of fluid and separation cross the wing to 10.

10 The structured mesh is performed in GAMBIT then is exported to ANSYS-FLUENT, this mesh type offers distinct advantages over unstructured; in their main features, the implementation is simple and suitable for the finite difference solution stands. For this analysis in ANSYS-FLUENT the SpalartAllmaras turbulence model was used, due its more common in aerospace-related limited by walls and model simulations at low Reynolds numbers flow applications.

11 EXPERIMENTAL CONFIGURATION The model was built in a 1:3 scale (taking into the dimensions of the test section of the wind tunnel LAE) made in MDF (Medium Density Fiberboard) with a thickness of 6.3x10-2 m, and PVC (Poly Vinyl Chloride) with 5x10-3 m thick and flexible plastic tubes at 25% of the chord for the pressure taps.

12 The experimental model used a semi-span of 1m, a chord of 0.13 m and a root tip of 0.05m, taper ratio of 0.375, having a constant section of 0.60 m and a sweep section at the tip of 0.40 m. The wind tunnel model is presented in the next picture:

13 LABORATORY AIRCRAFT EESC-USP The top view of the wind tunnel circuit closed LAE, School of Engineering of São Carlos, University of Sao Paulo, Brazil is illustrated. The dimensions of the test section of the tunnel is 3 m long, 1.30 m high and 1.70 m wide, with a level of 0.25% turbulence and maximum speed of 50 m / s.

14 GOALS The figures of the computationally data from ANSYS-FLUENT which are compared with experimental data, which are analyzed for the maximum speed of 25m / s with a variation of angle of attack of -4 to 18 are presented.

15 The Figure shows, that for low angles of attack the computational and experimental results are very close. However, from 8 begins to be a divergence in the results. Since an angle of 10 the slope of the curve changes and the growth rate decreases lift coefficient. 1,4 1,2 Coeficiente de Sustentación 1 0,8 0,6 0,4 0,2 Experimental Fluent 25 m/s ,2 Alpha Comparison of lift coefficient versus angle of attack.

16 Furthermore, an excellent approximation to lower angles of attack of experimental and computational results with regard to drag coefficient was obtained. 0,25 0,2 Coeficiente de Arrastre 0,15 0,1 Experimental Fluent 25 m/s 0, Alpha Comparison of drag coefficient versus angle of attack.

17 At the Figure, both experimentally and computationally the moment coefficient is negative, confirming that the wing has a tendency to have a static stability. 0,15 0,1 0,05 Coeficiente de momento ,05 y = -0,0072x + 0,0539-0,1 Fluent 25 m/s Experimental Linear (Fluent 25 m/s) Linear (Experimental) -0,15-0,2-0,25 Alpha Comparison of moment coefficient versus angle of attack.

18 The table shows the different results obtained are shown, for a speed of 25 m / s. Aerodynamic parameters Experimental ANSYS-FLUENT CL máximo 1,11 1,18 Alpha para CLmáx CD 0,126 0,110 Alpha para CD δcm / δalpha CL/CD máximo 22,23 24,88 Alpha para CL/CDmáx 4 5 CL^1,5/CD máximo 19,34 22,61 Alpha para CL^1,5/CD máximo 6 7 CL^0,5/CD máximo 28,46 30,67 Alpha para CL^0,5/CD máximo 4 5

19 CONCLUSION In developing the project was presented numerical and experimental analysis of the wing to the mini-uav Solvendus. Experimental results compared with computational simulations are next in relation to the aerodynamic coefficients. Aerodynamic efficiency (L / D) obtained was 4, so the angle of attack is recommended for best aerodynamic efficiency in cruise flight mini-drone. For three-dimensional analysis, favorable results were obtained with the ANSYS, FLUENT software.

20 With the turbulence model used, Spalart Allmaras consistent for models at low Reynolds numbers were obtained. Finally, the results suggest that the wing design is within the requirements proposed for implementation in the UAV- Solvendus.