Examinando por Autor "Bardera, Rafael"

Mostrando 1 - 16 de 16

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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.; Bardera, Rafael; Franchini, Sebastián; Barroso, Estela; Sor, Suthyvann; 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.
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Aerodynamic Flow Effects on Aircraft Carrier Takeoff Performance
(Aerospace Research Central, 2019-01-11) Bardera, Rafael; García Magariño, A.; Rodríguez Sevillano, A.; Barcala Montejano, M. Á.; Instituto Nacional de Técnica Aeroespacial (INTA)
The aircraft takeoff maneuver for onboard operations is the most critical aspect of maritime performance. In the last decades, several improvements have been made to reduce the number of accidents. One of them is the ski-jump ramp, a modern takeoff system that allows the maneuver to be performed more safely and using less runway distance. Thus, a new in-depth aerodynamic study of the ramp is required. A wind-tunnel test campaign was developed to study the disturbances caused by the ski-jump ramp over the flight deck and the influence on an aircraft carrier performance. Smoke visualizations over the ramp revealed a detached unsteady recirculation bubble at the ramp and a turbulent flow over the flight deck. Velocity measurements were carried out by means of particle image velocimetry. The influence of these disturbances was evaluated for the takeoff performance of the AV-8B Harrier II. The results proved the importance of taking into account these disturbance effects and provided a detailed characterization of the flow over the carrier deck, resulting in establishment of a useful background for future studies on aircraft–ship interference.
Acceso Abierto
Aerodynamic investigation of a morphing wing for micro air vehicle by means of PIV
(MDPI, 2020-10) Bardera, Rafael; Rodríguez Sevillano, A.; García Magariño, A.; 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.
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Aerodynamic optimization over frigate helicopter flight deck by Hangar shape modifications
(Elsevier, 2020-11-16) Bardera, Rafael; Matías García, J. C.; García Magariño, A.
Helicopter 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.
Acceso Abierto
Balance measurements on a frigate type ship model
(Elsevier, 2020-10-12) Bardera, Rafael; García Magariño, A.
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.
Restringido
Balance measurements on a frigate type ship model
(Elsevier LTD, 2020-10) Bardera, Rafael; García Magariño, A.; 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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Characterization of an electrostatic filter prototype for bioaerosol flowmetering for INTA Investigation Aerial Platforms
(Elsevier, 2019-08-20) Sor, Suthyvann; Bardera, Rafael; García Magariño, A.; González, Elena; Aguilera, Á.; Sor, Suthyvann; 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
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, A.; Matías García, J. C.; Donoso, Eduardo; Sor, Suthyvann; 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.
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Experimental and numerical characterization of the Flow around the Mars 2020 Rover
(Aerospace Research Central, 2018-04-30) Bardera, Rafael; García Magariño, A.; Gómez Elvira, J.; Marín Jiménez, M.; Navarro López, Sara; Torres Redondo, J.; Carretero, Sara; Sor, Suthyvann; 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.
Acceso Abierto
Impacts of Saharan Dust Intrusions on Bacterial Communities of the Low Troposphere
(Spring Nature Research Journals, 2020-04-22) González Toril, Elena; Osuna, Susana; Viúdez Moreiras, Daniel; Navarro Cid, Ivan; Del Toro, Silvia Díaz; Sor, Suthyvann; Bardera, Rafael; Puente Sánchez, Fernando; De Diego Castilla, Graciela; Aguilera, Á.; Osuna Esteban, Susana; Sor, Suthyvann; Ministerio de Economía y Competitividad (MINECO); Agencia Estatal de Investigación (AEI); 0000-0002-5750-0765; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
We 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.
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, Susana; Viúdez Moreiras, Daniel; Navarro Cid, Ivan; Díaz del Toro, Silvia; Sor, Suthyvann; Bardera, Rafael; Puente Sánchez, Fernando; De Diego Castilla, Graciela; Aguilera, Á.; Osuna Esteban, Susana; Sor, Suthyvann; Ministerio de Economía y Competitividad (MINECO); Agencia Estatal de Investigación (AEI); Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
We 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.
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, Susana; Viúdez Moreiras, Daniel; Navarro Cid, Ivan; Díaz del Toro, Silvia; Sor, Suthyvann; Bardera, Rafael; Sánchez, F. P.; De Diego Castilla, Graciela; Aguilera, Á.; Osuna Esteban, Susana; Sor, Suthyvann; Ministerio de Economía y Competitividad (MINECO); Agencia Estatal de Investigación (AEI); Sor, S. https://orcid.org/0000-0002-6972-8601
We 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.
Acceso Abierto
Interferometric laser imaging for droplet sizing method for long range measurements
(Elsevier, 2021-01-15) García Magariño, A.; Sor, Suthyvann; Muñoz Campillejo, Javier; Bardera, Rafael; Sor, Suthyvann; 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.
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Mars 2020 Rover Influence on Wind Measurements at Low Reynolds Number
(Aerospace Research Central, 2019-02-11) Bardera, Rafael; García Magariño, A.; Sor, Suthyvann; Urdiales, María del Mar; Sor, Suthyvann; 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.
Restringido
Mars 2020 Wind Velocity Measurement Interferences at High Reynolds Numbers
(Aerospace Research Central, 2019-12-29) García Magariño, A.; Sor, Suthyvann; Bardera, Rafael; Muñoz, Javier; Sor, Suthyvann; 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.
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.; Bardera, Rafael; García Magariño, A.; 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.