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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23 resultados
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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 Performance enhancement of a bioinspired micro air vehicle by integrating a smart composite in its morphing wing(Elsevier, 2023-05-23) Crespo Moreno, Javier; Rafael, Bardera Mora; Rodríguez Sevillano, A.; Cobo González, Alvaro; Instituto Nacional de Técnica Aeroespacial (INTA)The purpose of this paper is to show the advantages of using a smart composite in a micro air vehicle (MAV) equipped with morphing wing technology. A Macro Fiber Composite (MFC) actuator is attached to the wing’s bottom surface to modify the wing camber during the mission. This material allows the MAV to be optimized according to each flight, thus making it more versatile and attractive to the market. The elongation of the lower surface when a positive voltage is applied to the actuator is translated to an increment in camber, which results in an increment in the maximum lift coefficient, thus enabling the vehicle to fly slower to adapt to any payload. Besides, a reduction in camber results in an increase in aerodynamic efficiency, which improves range and endurance. Several tests of the MAV at prototype level have been carried out at INTA, so as to demonstrate the feasibility of implementing MFC actuators to control and manoeuvre these vehicles. The use of this material in aerospace industry opens up various fields of research in aerospace engineering, such as new features in flight mechanics and aerodynamic performance and new strategies in the design of flight stability and control laws.Publicación Restringido Aerodynamic optimization over frigate helicopter flight deck by Hangar shape modifications(Elsevier, 2020-11-16) Rafael, Bardera Mora; Matías García, J. C.; García-Magariño, AdelaidaHelicopter operations on frigates imply complex maneuvers for pilots. During the aircraft approach to the frigate, the helicopter rotor is immersed in a changing aerodynamic flow, with high speed and turbulence intensity gradients. This occurs as a consequence of the nonaerodynamic surfaces that compose the frigates and generate detached flow on their decks. Typically, the helicopter operations on frigates are located at the stern. That is, after the superstructure of the ship and just behind the hangar where the helicopter can be hosted. Using a simplified frigate shape model, tests have been carried out at the National Institute of Aerospace Technology’s low-speed wind tunnel by modifying the hangar geometry in a bubble-shaped way to optimize it aerodynamically and improve the flow over the frigate aftdeck. Roof and side walls have been modified by linearA, circular C, and elliptical E geometries. A particle image velocimetry (PIV) technique has been used for obtaining the flow velocity field above and behind the hangars proposed to evaluate the effectiveness of each geometry modification proposed. Finally, a numerical comparison with the PIV results and parameters such as the storage capacity reduction of the hangar due to its geometry change has been carried out.Publicación Restringido A comparative analysis of helicopter recovery maneuvers on a SFS by means of PIV and balance measurements(Elsevier, 2023-05-23) Matías García, J. C.; Rafael, Bardera Mora; Franchini, Sebastián; Barroso, Estela; Sor, Suthyvann; Instituto Nacional de Técnica Aeroespacial (INTA)The flow field around a frigate is complex due to flow detachments, high velocity gradients, and flow unsteadiness. These flow patterns can endanger helicopter operations around frigates and increase pilot workload above the flight deck. This paper contains a comparative analysis of three different recovery maneuvers: an approach from the stern in the centerline plane (S); a diagonal maneuver (D); and an L-shaped maneuver. The comparison is made using wind tunnel tests with a scaled frigate and a motorized helicopter. For the three maneuvers, velocity contours around the helicopter with Particle Image Velocimetry are obtained. An internal balance is also used to obtain forces and moments on the helicopter during the flight path of the maneuvers. Those measurements show that the wake of the ship mostly affects longitudinal and thrust forces. In addition, pitch torque is highly reduced when the helicopter is behind the frigate superstructure, and the roll moment is also important when the wind angle increases. In the end, an estimation of pilot workload is presented to conclude that L-shaped maneuver is the best for 0° and small WOD angles and D or S recoveries for moderately high negative WOD angles.Publicación Restringido Effect of the incident wind angle in a frigate with Coanda active flow control(Elsevier, 2023-06-01) Matías García, J. C.; Rafael, Bardera Mora; Barroso, Estela; Rodríguez Sevillano, A.; Instituto Nacional de Técnica Aeroespacial (INTA)The aerodynamic environment around frigates can be complex. This can cause helicopter pilots operating on frigates to face risky situations during the recovery maneuver. In this paper, the introduction of active flow control using Coanda effect has been tested to improve flow characteristics above a frigate flight deck. Wind tunnel tests with Particle Image Velocimetry (PIV) have been performed in order to analyze the effectiveness of introducing Coanda effect at the hangar at four different wind over deck conditions. Applying Coanda effect on the upper part of the frigate hangar the re-attachment distance, and the recirculation areas are reduced. When the Coanda effect is applied also on the sides, the flow recirculation can be completely eliminated, especially for WOD angles different from 0°. The profiles of velocities at the height where the helicopter rotor operates are also corrected, making them uniform and similar to the free stream velocity. In exchange, there is an increase in turbulence intensity close to the hangar, without affecting the rest of the flight deck. The results have shown that Coanda effect clearly improves the aerodynamics over the flight deck where the helicopter operates, and it could help to increase the safety of helicopter operations around frigates.Publicación Acceso Abierto Theoretical model for microbubble drag reduction technique applied to marine propellers(Elservier, 2025-06-15) García-Magariño, Adelaida; Sor, Suthyvann; Rafael, Bardera Mora; López Gavilán, Pablo; Instituto Nacional de Técnica Aeroespacial (INTA)An increase in the propeller efficiency could result in a reduction of the contaminant emissions of ships. The reduction of drag by means of injecting microbubbles in the boundary layer of the blade of propeller is first studied in this article based on the fluid mechanics theory and the fundamental knowledge of this recent technique (that is usually applied to the hull of ships instead). A theoretical approach is proposed to evaluate the drag reduction due to the bubbles presence inside the boundary layer. This is a new application of bubbles dynamic to reduce the drag of the blades of the marine propellers, thus increasing their efficiency.Publicación Restringido Experimental and numerical simulations of simple frigate with suction flow control over the deck(Elsevier, 2021-09-15) Rafael, Bardera Mora; Matías García, J. C.; Barroso, Estela; Instituto Nacional de Técnica Aeroespacial (INTA)The air wake generated behind a frigate superstructure is a very complex and unsteady three-dimensional flow characterized by highly turbulent flow structures with great velocity gradients that result in flow separation over the flight deck where helicopter erations take a significant role. Naturally, this turbulent flow should be removed or, at least, reduced as maximum as possible to avoid accidents during the interaction between frigates and helicopters. This paper involves experimental and numerical analysis on a simple frigate model (SFS2) to understand and simulate the adverse effect of the turbulent flow of the air wake over the deck and tries to minimize it as with active flow control. The experimental study has been performed in the Low Speed Wind Tunnel nº1 of nstituto Nacional de T´ecnica Aeroespacial ‘‘Esteban Terradas’’ (INTA) with Particle Image Velocimetry (PIV) to obtain the velocity field over the flight deck. The frigate has been tested for the headwind condition of 0◦ (wind aligned with the flight deck) with a elocity of 10 m/s. The active flow control consists on generating suction on the flight deck by a mesh of holes. Several configurations of this suction mesh have been studied according to the diameter and location of holes and suction intensity. The suction mesh configuration with the highest diameter and flow rate presents the greatest aerodynamic improvement. The low-speed area over the deck is reduced from 36% to a minimum of 3%.Publicación Restringido A comparison of helicopter recovery maneuvers on frigates by means of PIV measurements(Elsevier, 2021-01-21) Rafael, Bardera Mora; Matías García, J. C."Helicopter pilots who have to operate on frigates must deal with turbulent and unsteady flows caused by the incidence of the wind on the non-aerodynamic surfaces of the frigate. In addition, the flight deck is usually placed at the stern, right behind the frigate superstructure where recirculation and low-velocity regions appear. For that reason, studying how the aerodynamic effects influence the helicopter rotor during the approach and landing on the frigate could be essential to guarantee safe operations. The aim of this paper is to present PIV velocity maps with the flow patterns generated by the interaction between the frigate wake and the helicopter rotor working during its landing approach usually named as dynamic-interface. Three different landing maneuvers have been analyzed: rear, diagonal and aft-fore. The jet generated by the rotor will be used to obtain induced velocity profiles under the rotor. With these velocity profiles, rotor asymmetries during its working over the frigate are detected. With all data at each point of the maneuvers, a final comparison will be made to select the best procedure for helicopter recovery on frigates under different wind over deck conditions."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 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.
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