Examinando por Autor "Bardera, Rafael"

Mostrando 1 - 6 de 6

Acceso Abierto
Calibration of a 3-Component External Balance for MAVs Wind Tunnel Research
(Multidisciplinary Digital Publishing Institute (MDPI), 2024-12-02) Bardera, Rafael; Rodríguez Sevillano, A.; Barroso, Estela; Sor, Suthyvann; Matías García, J. C.; Sor, Suthyvann; Instituto Nacional de Técnica Aeroespacial (INTA)
This paper presents a 3-component external balance, specifically designed, built, and calibrated at the National Institute for Aerospace Technology (INTA) for measuring aerodynamic forces on Micro Aerial Vehicles in the wind tunnel. The balance employs high-precision strain gauge cells as its load-sensing elements, strategically positioned in a metallic structure to measure lift force, aerodynamic drag force, and pitching moment. The entire calibration process of the balance, including the mathematical formulation to derive the calibration matrix and the calibration bench designed and manufactured for this purpose, is detailed in this paper. Moreover, the complete analysis of component interferences of the aerodynamic components and an assessment of the uncertainties inherent in the system are presented.
Restringido
Characterization of an electrostatic filter prototype for bioaerosol flowmetering for INTA Investigation Aerial Platforms
(Elsevier, 2019-08-20) Sor, Suthyvann; Bardera, Rafael; García-Magariño, Adelaida; González, Elena; Aguilera, Angeles; Instituto Nacional de Técnica Aeroespacial (INTA)
The characterization of the airborne microorganisms at different altitudes of the atmosphere is usually conducted by means of aerial platforms. It is very interesting to know the biological processes in the atmosphere. However, there are problems associated to the fact that sampling systems are embarked on an aircraft and the low presence of microorganisms at high altitude. A prototype of a new electrostatic filter for bioaersol flowmetering dedicated to biology investigations has been developed. This prototype was designed to be installed on board in aerial platforms of INTA. The experimental characterization of the aerodynamic flow was performed in order to investigate the behaviour of the filter when different air intake widths and different mechanical deflectors are employed. A combination of these impactor with the filters based on industrial electrostatic precipitator technology have been studied. Non-intrusive Particle Image Velocimetry technique has been used to measure the flow field inside the filter when it was running under controlled conditions in laboratory. This study is a first investigation on the flow field of filter for bioaerosol flowmetering to be embarked on an aircraft. The results show the influence of each parameter in the flow field that could be used for further investigations and designs.
Acceso Abierto
Computational Study of Aerodynamic Effects of the Dihedral and Angle of Attack of Biomimetic Grids Installed on a Mini UAV
(Multidisciplinary Digital Publishing Institute (MDPI), 2023-12-29) Bardera, Rafael; Rodríguez Sevillano, A.; Barroso, Estela; Matías García, J. C.; Instituto Nacional de Técnica Aeroespacial (INTA); Ministerio de Defensa de España
In this paper, a numerical analysis of a biomimetic unmanned aerial vehicle (UAV) is presented. Its wings feature three grids at the tip similar to the primary feathers of birds in order to modify the lift distribution over the wing and help in reducing the induced drag. Numerical analysis using computational fluid dynamics (CFD) is presented to analyze the aerodynamic effects of the changes in dihedral and angle of attack (with respect of the rest of the wing) of these small grids at the tip. The aerodynamic performances (lift, drag, and efficiency) and rolling capabilities are obtained under different flight conditions. The effects of changing the dihedral are small. However, the change in the grid angle of attack increases aerodynamic efficiency by up to 2.5 times when the UAV is under cruise flight conditions. Changes to the angle of attack of the grids also provide increased capabilities for rolling. Finally, boundary values of the pressure coefficient and non-dimensional velocity contours are presented on the surfaces of the UAV, in order to relate the aerodynamic results to the aerodynamic patterns observed over the wing.
Acceso Abierto
Development and characterization of a low-cost wind tunnel balance for aerodynamic drag measurements
(IOP Science Publishing, 2019-06-17) Sor, Suthyvann; Bardera, Rafael; García-Magariño, Adelaida; Matías García, J. C.; Donoso, Eduardo; Instituto Nacional de Técnica Aeroespacial (INTA)
Drag force measurement is one of the most important data that can be obtained in wind tunnel tests. Drag force is directly related to the energy that a vehicle needs to move, and, therefore, to the fuel costs associated with it. For vehicles, drag forces are usually measured in wind tunnels. The typical instruments for drag measurement are the force balances, which are usually complex and expensive instruments. The aim of this investigation is to study the development of a low-cost in-house balance for drag measurements in a wind tunnel. Based on a commercial available load cell XFTC300 Series in combination with simple elements designed and manufactured at INTA, a balance capable of measuring the drag force to models in a considerably wide adjustable range has been developed and characterized. The balance has been calibrated and used in a wind tunnel. Tests were carried out on a truck model, a simplified frigate shape and an Ahmed Body to obtain the resistance coefficient and evaluate the operation of the balance.
Restringido
Experimental and numerical characterization of the Flow around the Mars 2020 Rover
(Aerospace Research Central, 2018-04-30) Bardera, Rafael; García-Magariño, Adelaida; Gómez Elvira, J.; Marín Jiménez, M.; Navarro López, Sara; Torres Redondo, J.; Carretero, Sara; Sor, Suthyvann; Instituto Nacional de Técnica Aeroespacial (INTA)
The investigation of the environmental factors in Mars atmosphere is one of the issues of the NASA’s Mars Exploration Program about the potential for life on Mars. The future Mars 2020 rover will transport the Mars Environmental Dynamics Analyzer dedicated to obtain meteorological data, as well as other objectives, about wind speed and direction. High-quality wind data are required to build mathematical models of the Mars climate; therefore, powerful techniques are necessary to eliminate flow perturbations produced by the rover presence. The aim of this Paper is the characterization of the flow around the Mars 2020 rover, providing a deep insight into the environmental interaction of the Mars wind with the rover. A comparative study between numerical simulations versus wind-tunnel experimental results is conducted trying to investigate the influence of the rover on the flow measured by the Mars Environmental Dynamics Analyzer wind sensors. This study is addressed to perform an assessment of the reliability of numerical methods in the prediction of this kind of flow in Martian conditions, evaluating its capability to be used in the future to correct wind data coming from the Mars 2020 rover mission. The advancements in the numerical methods as compared with experimental results implies an advancement on the calibration methods in the space wind sensor instrumentation carried in the Mars 2020 rover.
Restringido
Helicopter Rotor Ground Effect and Frigate Interaction Investigated by Particle Image Velocimetry
(American Institute of Aeronautics and Astronautics (AIAA), 2021-08-23) Bardera, Rafael; Matías García, J. C.; Instituto Nacional de Técnica Aeroespacial (INTA)
Helicopter maneuvers on frigates develop an essential role during military operations. However, the complex flow generated by the frigate bluff-body shapes and the interaction with the helicopter downwash during the recovery process must be studied in detail. In addition, the ground effect can also affect helicopter performance during the maneuver. This study aims to use particle image velocimetry in wind tunnel to analyze the airflow generated by a 1:100-scaled helicopter rotor of the Sea King SH-3 navy helicopter isolated and with the presence of a full and a partial ground to consider the ground effect at different heights. Once the rotor has been studied, experimental tests were carried out of the rotor working next to a frigate model during the recovery maneuver. The measured velocity indicates that the flow asymmetry below the rotor can increase with the proximity to a partial ground distance up to 1.39 times. During the study of the rotor for the frigate landing approach, the downwash asymmetry is also important and changes abruptly the tendency during the last phase of the maneuver. It can lead to dangerous instabilities and problems for the helicopter pilot during the hovering over ships.