Persona: Rafael, Bardera Mora
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Instituto Nacional de Técnica Aeroespacial
El Instituto Nacional de Técnica Aeroespacial es el Organismo Público de Investigación (OPI) dependiente del Ministerio de Defensa. Además de realizar actividades de investigación científica y de desarrollo de sistemas y prototipos en su ámbito de conocimiento, presta servicios tecnológicos a empresas, universidades e instituciones.
El INTA está especializado en la investigación y el desarrollo tecnológico, de carácter dual, en los ámbitos de la Aeronáutica, Espacio, Hidrodinámica, Seguridad y Defensa.
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Rafael
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Bardera Mora
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Mostrando 1 - 10 de 23
Publicación Acceso Abierto Wind Tunnel Balance Measurements of Bioinspired Tails for a Fixed Wing MAV(Multidisciplinary Digital Publishing Institute (MDPI), 2024-01-10) Rafael, Bardera Mora; Rodríguez Sevillano, A.; Barroso, Estela; Matías García, J. C.; Sor, Suthyvann; Instituto Nacional de Técnica Aeroespacial (INTA)"Bird tails play a significant role in aerodynamics and stability during flight. This paper investigates the use of bioinspired horizontal stabilizers for Micro Air Vehicles (MAVs) with Zimmerman wing-body geometry. Five configurations of bioinspired horizontal tabilizers are presented. Then, 3-component external balance force measurements of each horizontal stabilizer are performed in the wind tunnel. The Squared-Fan-Shaped Horizontal Stabilizer (HSF-tail) is selected as the optimal horizontal stabilizer that provides the highest aerodynamic efficiency during cruise flight while maintaining high longitudinal stability on the vehicle. The integration of the HSF-tail increases the aerodynamic efficiency by more than 6% up to a maximum of 17% compared to the other alternatives while maintaining the lowest aerodynamic drag value during the cruise phase. Furthermore, balancemeasurements to analyze the influence of the HSF-tail deflection on the aerodynamic coefficients are conducted, resulting in increased lift force and reduced aerodynamic drag with negative tail deflections. Lastly, the experimental data is validated with CFD-RANS steady simulations for low angles of attack, obtaining a relative difference on the measurement around 5% for the aerodynamic drag coefficient and around 10% for the lift coefficient during the cruise flight that demonstrates a high degree of accuracy in the aerodynamic coefficients obtained by external balance in the wind tunnel. This work represents a novel approach through the implementation of a horizontal tabilizer inspired by the structure of the tails of birds that is expected to yield significant advancements in both stability and aerodynamic efficiency, with the potential to revolutionize MAV technology."Publicación Acceso Abierto CFD study of the effect of leading-edge tubercles on the aerodynamic characteristics of a small UAV based on eppler 186 airfoils(Elsevier, 2024-09-12) Rafael, Bardera Mora; Rodríguez Sevillano, A.; Barroso, Estela; Matías García, J. C.; Instituto Nacional de Técnica Aeroespacial (INTA)A numerical analysis is carried out to evaluate the aerodynamic characteristics of a small Unmanned Aerial Vehicle (UAV) whose wings are modified to incorporate sinusoidal leading edges (tubercles). This UAV has a rectangular wing composed of Eppler 186 airfoils. The aerodynamic characteristics of four UAV configurations varying the wavelength and amplitude along the wingspan are evaluated using Computational Fluid Dynamics (CFD). Results are compared with the baseline case, that is, without leading-edge tubercles. The wing configu rations with tubercles exhibited increased lift at high angles of attack and delayed stall. The configuration with maximum amplitude (a = 0.05c) and minium wavelength (λ = 0.25c) achieved an increase up to 17 % in the maximum lift coefficient and delayed the stall up to the angle of attack of 20◦ compared to the baseline case.Publicación Restringido Balance measurements on a frigate type ship model(Elsevier, 2020-10) Rafael, Bardera Mora; García-Magariño, Adelaida; Instituto Nacional de Técnica Aeroespacial (INTA)Balance measurements performed by testing sub-scaled ship models determine the global forces and moments acting on the ship, which allows knowing the power required for the ship's movement and provides insight to be applied in the design of the control systems used to steer the ship and to avoid instabilities while sailing. The ship superstructure may produce large separated regions and high air wake turbulence levels resulting in a set of fluctuations of the flow parameters usually determined by measuring velocity or pressure. This paper presents the balance measurement of the aerodynamic forces acting on the ship hull. Aerodynamic forces and moments produced on the ship can be interpreted as an integration of the flow parameters (velocity and pressure distributions) over the ship surface wetted by the air. Balance method provides averaged values and fluctuations of forces coefficients. Aerodynamic environment in the vicinity of a ship is influenced by a large number of factors (atmospheric wind, sea state, ship superstructure, masts, stacks, antennas …) affecting helicopter operations on board ships and their safety during the take-off and landing manoeuvres.Publicación Acceso Abierto Aerodynamic investigation of a morphing wing for micro air vehicle by means of PIV(MDPI, 2020-10) Rafael, Bardera Mora; Rodríguez Sevillano, A.; García-Magariño, Adelaida; Ministerio de Defensa; García Magariño, A. [0000-0002-6039-8407]A wind tunnel tests campaign has been conducted to investigate the aerodynamic flow around a wing morphing to be used in a micro air vehicle. Non-intrusive whole field measurements were obtained by using PIV, in order to compare the velocity and turbulence intensity maps for the modified and the original version of an adaptive wing designed to be used in a micro air vehicle. Four sections and six angles of attack have been tested. Due to the low aspect ratio of the wing and the low Reynold number tested of 6.4 × 104, the influence of the 3D effects has been proved to be important. At high angles of attack, the modified model prevented the detachment of the stream, increased the lift of the wing and reduced the turbulence intensity level on the upper surface of the airfoil and in the wake.Publicación Acceso Abierto Selection criteria for biplane wing geometries by means of 2D wind tunnel tests(Multidisciplinary Digital Publishing Institute (MDPI), 2022-05-16) Rodríguez Sevillano, A.; Barcala Montejano, M. Á.; Rafael, Bardera Mora; García-Magariño, Adelaida; Rodríguez Rojo, María Elena; Morales Serrano, Sara; Fernández Antón, Jaime; Instituto Nacional de Técnica Aeroespacial (INTA)This paper presents a study based on wind tunnel research on biplane configurations. The objective of this research is to establish an experimental basis for relationships between the main geometrical parameters that define a biplane configuration (stagger, decalage, gap, and sweep angle) and the aerodynamic characteristics (CL, CD). This experimental study focuses on a 2D approach. This method is the first step towards dealing with the issue, and it allows the variables involved in the tests to be reduced. The biplane configuration has been compared with the monoplane configuration to analyze the viability for implementing the biplane configuration in the field of application for micro air vehicles (MAV). At present, the biplane and other unusual configurations have not been a common design for MAV; however, they do have unlimited future potential. A set of experimental tests were carried out on various biplane configurations at low Reynolds numbers, which allowed the criteria for selecting the best wing configuration to be defined. The results obtained here show that the biplane configuration provides a higher maximum lift coefficient (CLmax) than the planar wing (monoplane). Furthermore, it has a larger wetted surface than the planar configuration, so the parasitic drag increases for the biplane configuration. This research is focused on a drone flight regime (low Reynolds number), and in this case, the parasitic drag (profile drag) has an important role in the total drag of the airplane. This study considers whether the reduction in the induced drag due to three–dimensional configuration (biplanes, box–wings, and joined–wings) can reduce the total drag or if the increase in the parasitic drag is bigger. Additionally, the increase in lift and the decrease in parasitic drag (profile drag) will be studied to determine if they have a greater influence on the performance of the airplane than the increase in structural weight. Further research is planned to be performed on 3D prototypes, with the selected configurations, and applied to nonconventional wing planforms.Publicación Acceso Abierto Numerical analysis of the thermal convection through a flat plate in Martian conditions(Elsevier, 2024-06-11) Rafael, Bardera Mora; Rodríguez Sevillano, A.; Barroso, Estela; Matías García, J. C.; López Cuervo, Alejandra; Instituto Nacional de Técnica Aeroespacial (INTA)There are currently several investigations being developed around Mars, primarily focused on the aerodynamics of drones and the study of atmosphere flow and Martian soil with the assistance of the Perseverance rover. Several phenomena in the Martian atmosphere can complicate flow measurements, and the Multi Mission Radioisotope Thermoelectric Generator (MMRTG) at the rear of the rover can introduce additional uncertainty to the measurements. These measurements are conducted with the system called MEDA, which is located at the front of the rover, under its head. Therefore, it is considered of interest to carry out a preliminary study to determine the feasibility of performing tests on Earth simulating the Martian atmosphere without the need for a vacuum chamber. This would make it possible to streamline and simplify the methods used. The aim of this work is to perform simulations on a plate, that can be considered as a simplification of the MMRTG heat exchanger system, which is composed of a cylinder with flat fins around it, over free and forced convection to verify whether flow behaviour in Martian conditions can be obtained from dimensional analysis on Earth.Publicación Restringido Comparison of BEM and CFD results for MEXICO rotor aerodynamics(Elsevier, 2015-07-07) Plaza Gallardo, Borja; Rafael, Bardera Mora; Visiedo Martínez, S.This work aims to conduct an aerodynamic analysis of the MEXICO wind turbine rotor, establishing comparisons between the results of two radically different computational techniques and measurements, obtained in wind tunnel tests under controlled conditions in the framework of the MEXICO project (Boorsma and Schepers, 2009, Schepers et al., 2012). Forces, pressures, and torque generated in the rotor are computed usingthe blade element momentum (BEM) and computational fluid dynamics (CFD) codes to investigate their main strengths and weaknesses at different wind speeds, highlighting the quality of the results obtained at different blade stations. In general terms, both methods tend to overestimate the spanwise distribution of forces and pressures. Reynolds-averaged Navier–Stokes (RANS)-CFD simulations maintain a uniform level of accuracy across the studied velocity range, whereas BEM calculations outperform CFD estimates at low wind velocities but fail at higher velocities due to separated flow conditions. Blade tip loss and three-dimensional (3D) effects are partly responsible for inaccuracies in calculation, especially for the BEM code. These 3D effects are discussed briefly in relation to force estimates.Publicación Acceso Abierto From conventional to bioinspired: Evolution of tail surface designs in micro air vehicles(Elsevier, 2024-12-23) Rodríguez Sevillano, A.; Rafael, Bardera Mora; Barroso, Estela; Matías García, J. C.; López Cuervo, Alejandra; Instituto Nacional de Técnica Aeroespacial (INTA)The paper presents the evolution of the tail surface design of a micro air vehicle based on adaptive wing geometry. The initial prototype was conceived as a tailless aircraft geometry, waiting for future innovations and stability augmentations. An initial experimental test bench will be presented to characterize the variation of wing profile curvature as a function of the voltage, through MFC actuators. Once these results have been analyzed, the process of conceiving a conventional T-tail was initiated, ultimately evolving toward the proposal of a bioinspired tail based on the tail shape of various birds. The results obtained in wind tunnel tests using PIV techniques will be presented. The results validate the selected tail surface design as an appropriate geometry for a bioinspired micro air vehicle.Publicación Acceso Abierto Impacts of Saharan Dust Intrusions on Bacterial Communities of the Low Troposphere(Springer Nature Research Journals, 2020-04-22) González-Toril, Elena; Osuna Esteban, Susana; Viúdez Moreiras, Daniel; Navarro Cid, Ivan; Díaz del Toro, Silvia; Sor, Suthyvann; Rafael, Bardera Mora; Puente-Sánchez, Fernando; De Diego Castilla, Graciela; Aguilera, Angeles; Ministerio de Economía y Competitividad (MINECO); Agencia Estatal de Investigación (AEI); Sor, S. https://orcid.org/0000-0002-6972-8601We have analyzed the bacterial community of a large Saharan dust event in the Iberian Peninsula and, for the first time, we offer new insights regarding the bacterial distribution at different altitudes of the lower troposphere and the replacement of the microbial airborne structure as the dust event receeds. Samples from different open-air altitudes (surface, 100 m and 3 km), were obtained onboard the National Institute for Aerospace Technology (INTA) C-212 aircrafts. Samples were collected during dust and dust-free air masses as well two weeks after the dust event. Samples related in height or time scale seems to show more similar community composition patterns compared with unrelated samples. The most abundant bacterial species during the dust event, grouped in three different phyla: (a) Proteobacteria: Rhizobiales, Sphingomonadales, Rhodobacterales, (b) Actinobacteria: Geodermatophilaceae; (c) Firmicutes: Bacillaceae. Most of these taxa are well known for being extremely stress-resistant. After the dust intrusion, Rhizobium was the most abundant genus, (40–90% total sequences). Samples taken during the flights carried out 15 days after the dust event were much more similar to the dust event samples compared with the remaining samples. In this case, Brevundimonas, and Methylobacterium as well as Cupriavidus and Mesorizobium were the most abundant genera.Publicación Acceso Abierto CFD Study of Flow Field Velocities and 3D Effects over the MEXICO Wind Turbine Model(Science Publishin Group, 2017-12-13) Plaza Gallardo, Borja; Rafael, Bardera Mora; Visiedo Martínez, S.The deep understanding about wake field and 3D effects of wind turbines are still a challenge, due to the complexity of the three-dimensional flow which blades rotation produces. In this work an aerodynamic analysis about wind turbine model MEXICO is realized, firstly of axial distribution of velocities in several regions inside the streamtube and then some estimations of 3D effects, either lift coefficient augmentation or stall delay phenomenon. CFD-RANS simulations have been carried out at three different wind speeds, and results are compared to experimental data of the MEXICO project, from wind tunnel tests. Results show that axial and radial inductions are greater for outer sections and lower as wind speed increases, providing different wake configurations. As for the 3D effects, it is found that rotational augmentation appears firstly for inner part of the blade and they advance progressively towards span-wise direction as wind velocity grows. For inner section, at high wind speed, lift coefficient increase reaches to values of 50% over the corresponding 2D polar curve.
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