Persona: Rafael, Bardera Mora
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Rafael
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Bardera Mora
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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 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 Optimization of passive flow control above the ski jump ramp of an aircraft carrier by CFD and experimental investigation(Elsevier, 2022-11-22) Rafael, Bardera Mora; Matías García, J. C.; Instituto Nacional de Técnica Aeroespacial (INTA)Aircraft carriers are a very useful operational tool for military operations. They are designed to provide service to aircraft at sea. For that reason studying the aerodynamic flow on their decks is essential. During take-off and landing maneuvers the aircraft can be affected by the turbulent flow generated by the non-aerodynamic surfaces that compose the geometry of the ship. Specifically, this study uses Computational Fluid Dynamics (CFD) applied to an aircraft carrier. The goal is to analyze and modify the flow detachment generated by the ski jump ramp on the flight deck that can affect the aircraft performances during take-off maneuvers. Passive flow control techniques such as holes in the ramp to allow airflow entering over the deck or aerodynamic devices added in the ramp corner have been tested. Different parameters of the devices have been studied and partial and even complete elimination of the flow detachment has been achieved. Finally, the numerical model has been compared with experimental wind-tunnel tests. They have demonstrated a full elimination of the flow detachment and up to 80% of turbulence intensity reduction above the ski jump ramp of the aircraft carrier.Publicación Restringido Mars 2020 Wind Velocity Measurement Interferences at High Reynolds Numbers(Aerospace Research Central, 2019-12-29) García-Magariño, Adelaida; Sor, Suthyvann; Rafael, Bardera Mora; Muñoz, Javier; Instituto Nacional de Técnica Aeroespacial (INTA)The Mars Environmental Dynamics Analyzer will be dedicated to getting meteorological data from Mars during NASA’s Mars 2020 rover mission. High-quality Mars atmosphere measurements are required in order to build mathematical models of the climate on a planetary scale. The Mars 2020 rover will be equipped with two wind sensors installed on two separated booms working in active redundancy but producing a mutual aerodynamic interference on one another’s wind measurements. This paper presents a systematic study on the interferences produced by the sensors and the rover body itself when measuring wind velocities in order to get insight to assess the uncertainties produced by this effect.Publicación Acceso Abierto Interferometric laser imaging for droplet sizing method for long range measurements(Elsevier, 2021-01-15) García-Magariño, Adelaida; Sor, Suthyvann; Muñoz Campillejo, Javier; Rafael, Bardera Mora; Instituto Nacional de Técnica Aeroespacial (INTA)A recent appendix in the aircraft regulations comprises testing supercooled large droplets impinging on its surfaces. For those tests, the size and distributions of droplets need to be characterized in icing wind tunnels. In this paper, the applicability of implementation of the “Interferometric Laser Imaging for Droplet Sizing” technique inside a wind tunnel with a 3 m × 2 m open elliptical test section has been discussed. Experiments have been conducted in the laboratory for the discussion at object distance of 1.6 m and 2.29 m and droplets diameters between 360 µm and 850 µm. All the streams were previously characterized by means of the shadowgraph imaging technique. A novel approach of the Interferometric Laser Imaging for Droplet Sizing technique where droplets are not fully defocused to avoid excessive overlapping is presented. Two new image processing approaches provide in general good results as compared to previous methods.Publicación Acceso Abierto Numerical Analysis of Bioinspired Tails in a Fixed-Wing Micro Air Vehicle(Multidisciplinary Digital Publishing Institute (MDPI), 2023-09-08) Rafael, Bardera Mora; Barroso, Estela; Rodríguez Sevillano, A.; Matías García, J. C."Bird tails play a key role in aerodynamics and flight stability. They produce extra lift for takeoff and landing maneuvers, enhance wing functions and maintain stability during flight (keeping the bird from yawing, rolling and pitching, or otherwise losing control). This paper investigates the use of bioinspired horizontal stabilizers for Micro Air Vehicles (MAVs) involving a Zimmerman wing-body geometry. A selection of five tail shapes of the main types existing in nature is presented, and a parametric analysis is conducted looking into the influence of the most relevant tail geometric parameters to increase the longitudinal static stability of the vehicle. Based on the parametric study, a smaller subset of candidate tail designs are shortlisted to perform a detailed aerodynamic analysis. Then, steady RANS CFD simulations are conducted for a higher-fidelity study of these candidate tail designs to obtain an optimum of each tail type. The criterion for selection of the optimum tail configuration is the maximum aerodynamic efficiency, CL /CD , as well as a high longitudinal static stability. The squared-fan tail provides the highest aerodynamic efficiency while maintaining a high longitudinal stability of the vehicle. In conclusion, this paper provides an innovative study of improving longitudinal stability and aerodynamics through the implementation of bioinspired horizontal stabilizers in vehicles with these characteristics."Publicación Restringido Mars 2020 Rover Influence on Wind Measurements at Low Reynolds Number(Aerospace Research Central, 2019-02-11) Rafael, Bardera Mora; García-Magariño, Adelaida; Sor, Suthyvann; Urdiales, María del Mar; Instituto Nacional de Técnica Aeroespacial (INTA)The Mars 2020 rover is the new vehicle dedicated to the Martian surface investigation. This vehicle will transport Mars Environmental Dynamic Analyzer, the new meteorological station, including two wind sensors installed in the camera mast. An experimental characterization was conducted to investigate the influence of the Mars 2020 rover in the Mars Environmental Dynamic Analyzer wind measurements at low Reynolds numbers. Wind tunnel experiments were conducted using a 1:45th scaled model in a wind tunnel specially designed for these experiments. The velocity was measured using laser Doppler anemometry. A method is proposed in this investigation to calculate a correction factor for the data measurements of wind sensors embarked on rovers dedicated to planetary exploration missions. In particular, the method was applied to wind measurements taken by Mars Environmental Dynamic Analyzer in the Mars 2020 rover using the laser Doppler anemometry measurements, and corrections up to 40% in the velocity magnitude and 23 deg in the deflection angle were found.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.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.
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