A practical engineering approach to the design and manufacturing of a mini kW blade wind turbine : definition, optimisation and CFD analysis

A practical engineering approach to the design of a 60 kW wind generator with improved performances is presented. The proposed approach relies on the use of a specific, “ad hoc” developed software, OPTIWR (Optimization Software), expressly conceived to define an “optimum” rotor configuration in the framework of the blade element-momentum theory. Starting from an initial input geometric configuration (corresponding to an already existing 50 kW turbine) and for given values of the wind velocity Vwind and of the advance ratio X = Vwind/ΩR (where Ω is the blade rotational speed and R is the propeller radius), this software is used to determine iteratively the optimized distributions of chords and twists which can guarantee a constant value of the socalled axial induction factor a = 1/3 along the blade. The output configuration is then converted into a CAD model to be used, in turn, as input data for a CFD commercial software. With this tool the relative rotational motion between the fluid and the wind turbine are simulated resorting to a MRF (Moving Reference Frame) technique (for which continuity and momentum equations are solved in a rotating reference frame). The outcomes of the numerical simulations are then used to verify the improved performances of the optimized configuration and to which extent the CFD data agree with “expected” behaviours (i.e. performances predicted on the basis of the simplified model). Finally, some details about the construction technique used to turn the optimized configuration into an effective working prototype are provided, in conjunction with a critical discussion of suitable production methods for composite components

Innovative Aircraft Aeroelastic Modelling and Control

The aeroelastic design of innovative aircraft wing configurations imposes the designer to deal with specific phenomena, which are not usually considered in classical aircraft definition. The design process itself, though, gives the designer several indications on how to maintain the safety standards imposed by regulations. The investigation of the basic aeroelastic principles for unconventional wings with high aspect ratios can be extremely interesting as, once introduced in a multidisciplinary design, they can be very effective in giving an early determination of the static and dynamic behaviour of the aircraft, leading to significant improvements in the configuration weight, cost, and overall performance. The paper shows some preliminary results as part of the main objectives of the In.A.Team group (Innovative Aircraft Theoretical-Experimental Aeroelastic Modelling) at Politecnico di Torino, Italy. The In.A.Team Project has the following main objectives: 1) to develop multidisciplinary analysis methods appropriate to unconventional aircrafts (highly flexible, "morphing" vehicles); 2) to develop the capability of illustrating and understanding the effects of uncertainties on the behaviour of an aeroelastic system; 3) to apply the innovative adaptive L1 control techniques to highly flexible wings, 4) to integrate theoretical analysis with commercial structural (FEM) and aerodynamic tools (CFD). 5) to design and manufacture an aeroelastic experimental-test-model. 6) to validate theoretical/numerical results by vibration and aeroelastic wind tunnel tests

Practical considerations for the design of an aeroelastic energy harvester

Achieving the optimal balance between weight and energy consumption during flight mission remains a challenge for the design of very efficient high altitude long endurance aircrafts (HALE). These aircraft are intended to have flight missions that can range from 30 to 90 days. Composite materials are used to provide the structural integrity of the aircraft while minimizing its weight. Typically composites are used in long and slender structural elements of the HALE and are the main drivers of dynamic aeroelastic instabilities, even at low speed. This is due to the higher structural flexibility they introduce. Therefore, in order to respond to the demand of HALE aircrafts of having a wider amount of energy on board, without any substantial weight penalization, an experimental piezoelectric wing have been designed with the aim of exploiting aeroelastic instabilities or any other type of induced vibrations to generate electric energy directly on board. The numerical model of the piezoelectric wing, presented in this paper, is built starting from the assumptions of the 3D Euler-Bernoulli beam theory and of the strip theory for the aerodynamic loads. A preliminary sensitivity study was carried out, over the flutter solutions, for the identification of a suitable experimental prototype, to be used for modal and wind tunnel tests. The test campaign showed a good agreement between numerical and experiments results, highlighting, above all, the encouraging results in terms of energy harvesting and in terms of the exploitation potential of the piezoelectric design in the dynamic of structures

Structural aerospace composite/metallic samples under fatigue loads: experimental activity on three case studies

The use of composite materials in aerospace engineering is ever increasing. Properties such as low weight, high performance, high stiffness and the ability for it to be tailored specifically for different structural uses has increased its importance in recent years. Specific experimental/numerical activities were developed in the last decade at the Aerospace Department of POLITO and are under consideration in recent years regarding the analysis of fatigue behavior of composite/metallic structural samples under cyclic loading condition. A review of the main significant results connected to three case-studies are presented in the paper. The first is related to the definition and analysis of innovative joint for composite high aspect ratio aircraft structures. The modular design oriented to limit component dimensions for transportability requires the presence of a removable joints able to overcome the typical low bearing failure level of composite pin-loaded joint under static and fatigue loading distribution according to airworthiness requirements. The second is related to the presence of specific damaged situation in thin-walled flat/stiffened composite plate. Stiffened configurations are frequently used to increase buckling load level. Unexpected events on solid/stiffened composite panels can introduce a certain level of damage, typically delamination, that can cause reduction in buckling design level and reduction in global strength. The presence of cyclic load and fatigue effect can have an important consequence on damage propagation and structural integrity. The third is related to preliminary investigation on the effect of fatigue life reduction of 2024 Al alloy in corrosive (exfoliation) environment. The effect of corrosion is taken into consideration introducing specific concentration factors into the life estimation relationship. Differences between fatigue in prior corroded specimens and fatigue in presence of corrosive environment are emphasized. No crack propagation is considered. Related concentration factors are derived and compared by the few experimental results in order to define some guidelines for design process and to improve aircraft better evaluation of component structural integrity in operative situation

Apropiación de los dispositivos lectores de tinta electrónica en personas mayores de 55 años

En este momento estamos asistiendo a una penetración cada vez mayor de los libros electrónicos y los dispositivos móviles que se utilizan para el consumo en la vida diaria de muchos usuarios. Desde el comienzo de la comercialización de dispositivos lectores de tinta electrónica, la FGSR y el Orionmedialab colaboran en la investigación de los procesos de apropiación tecnológica para la lectura y la educación. En este trabajo, se presentan los resultados obtenidos con personas mayores de 55 años en una investigación llevada a cabo en el año 2010 con una muestra de cuarenta lectores divididos en dos grupos, de control y experimental. El objetivo es conocer, mediante la triangulación de metodologías cuantitativas y cualitativas, el grado de satisfacción de los usuarios con la nueva tecnología, así como la integración de la misma en sus costumbres como lectores. A partir de los presupuestos teóricos que subyacen al estudio, se diseñó un proceso de acompañamiento diferente para cada uno de los grupos, de forma que, además de los datos, se pudieran extraer conclusiones acerca del modo de implantación de tecnologías emergentes en este grupo de edad