(Aeronáutica) Artículos

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10,000 h molten salt corrosion testing on IN617, uncoated and aluminide ferritic steels at 580 ºC
(Richter C., 2020-12) Agüero, A.; Audigié, P.; Rodríguez, Sergio; European Commission (EC)
Long term testing of two ferritic-martensitic steels (P91 and VM12-SHC) with and without slurry deposited aluminide coatings containing 20 wt.% of Al at the surface was carried out by exposing these materials to the Solar Salt, a eutectic mixture composed of 60 % NaNO3 - 40 % KNO3 at 580ºC. This salt is currently used in operating thermal solar power plants as heat transfer and storage fluid. Tubes made of expensive Ni based alloys are employed to mitigate corrosion. The tested uncoated ferritic materials exhibited very high corrosion rates developing thick, easily detached scales. IN617 was also tested as a reference and experienced very low corrosion up to 5,000 h, but after 10,000 h a 50 ȝm thick, mostly NiO scale had developed with Na0.6CoO2 crystals deposited on top. There was also evidence of significant Cr depletion at the alloy surface. Carcinogenic CrVI was found in the Solar Salt melt in which the three uncoated alloys were immersed. In contrast, the two coated ferritic steels did not show evidence of degradation after 10,000 h and the most significant microstructural change was the development of a very thin protective NaAlO2 layer on their surface. An industrial process to deposit these coatings on the inner surfaces of pipes has already been developed.
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A chamber for studying planetary environments and its applications to astrobiology
(IOP Science Publishing, 2006-07-13) Mateo Martí, Eva; Prieto Ballesteros, O.; Sobrado, J. M.; Gómez Elvira, J.; Martín Gago, J. A.; Instituto Nacional de Técnica Aeroespacial (INTA); Comunidad de Madrid
We have built a versatile environmental simulation chamber capable of reproducing atmospheric compositions and surface temperatures for most of the planetary objects. It has been especially developed to make feasible in situ irradiation and characterization of the sample under study. The total pressure in the chamber can range from 5 to 5 × 10−9 mbar. The required atmospheric composition is regulated via a residual gas analyser with ca ppm precision. Temperatures can be set from 4 K to 325 K. The sample under study can be irradiated with ion and electron sources, a deuterium ultraviolet (UV) lamp and a noble-gas discharge UV lamp. One of the main technological challenges of this device is to provide the user the possibility of performing ion and electron irradiation at a total pressure of 0.5 mbar. This is attained by means of an efficient differential pumping system. The in situ analysis techniques implemented are UV spectroscopy and infrared spectroscopy (IR). This machine is especially suitable for following the chemical changes induced in a particular sample by irradiation in a controlled environment. Therefore, it can be used in different disciplines such as planetary geology, astrobiology, environmental chemistry, materials science and for instrumentation testing.
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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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A Comparative Study on HCN Polymers Synthesized by Polymerization of NH4CN or Diaminomaleonitrile in Aqueous Media: New Perspectives for Prebiotic Chemistry and Materials Science
(Chemistry Europe: European Chemical Societies Publishing, 2019-08-02) Ruiz Bermejo, Marta; De la Fuente, J. L.; Carretero González, J.; García Fernández, L.; Rosa Aguilar, M.; 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
HCN polymers are a group of complex and heterogeneous substances that are widely known in the fields of astrobiology and prebiotic chemistry. In addition, they have recently received considerable attention as potential functional material coatings. However, the real nature and pathways of formation of HCN polymers remain open questions. It is well established that the tuning of macromolecular structures determines the properties and practical applications of a polymeric material. Herein, different synthetic conditions were explored for the production of HCN polymers from NHCN or diaminomaleonitrile in aqueous media with different concentrations of the starting reactants and several reaction times. By using a systematic methodology, both series of polymers were shown to exhibit similar, but not identical, spectroscopic and thermal fingerprints, which resulted in a clear differentiation of their morphological and electrochemical properties. New macrostructures are proposed for HCN polymers, and promising insights are discussed for prebiotic chemistry and materials science on the basis of the experimental results.
Acceso Abierto
A dual perspective on the microwave-assisted synthesis of HCN polymers towards the chemical evolution and design of functional materials
(Nature Research Journals, 2020-12-18) Hortal, Lucia; Pérez Fernández, Cristina; De la Fuente, J. L.; Valles González, M. P.; Mateo Martí, Eva; Ruiz Bermejo, Marta; Instituto Nacional de Técnica Aeroespacial (INTA); Agencia Estatal de Investigación (AEI); http://dx.doi.org/10.13039/501100011033; http://dx.doi.org/10.13039/501100010687; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
In this paper, the first study on NH4CN polymerization induced by microwave radiation is described, where a singular kinetic behaviour, especially when this reaction is conducted in the absence of air, is found. As a result, a complex conjugated N-heterocyclic polymer system is obtained, whose properties are very different, and even improved according to morphological features, characterized by their X-ray diffraction patterns and scanning electron microscopy analysis, with respect to those produced under conventional thermal treatment. In addition, a wide variety of relevant bioorganics have been identified, such as amino acids, nucleobases, co-factors, etc., from the synthetized NH4CN polymers. These particular families of polymers are of high interest in the fields of astrobiology and prebiotic chemistry and, more recently, in the development of smart multifunctional materials. From an astrobiological perspective, microwave-driven syntheses may simulate hydrothermal environments, which are considered ideal niches for increasing organic molecular complexity, and eventually as scenarios for an origin of life. From an industrial point of view and for potential applications, a microwave irradiation process leads to a notable decrease in the reaction times, and tune the properties of these new series macromolecular systems. The characteristics found for these materials encourage the development of further systematic research on this alternative HCN polymerization.
Acceso Abierto
Adhesives Based on Poly(glycidyl methacrylate-co-butyl acrylate) with Controlled Structure: Curing Behavior and Adhesion Properties on Metal Substrates
(Wiley, 2023-10-26) Cañamero, Pedro; Fernández García, Marta; De la Fuente, J. L.; Ministerio de Ciencia e Innovación (MICINN); Instituto Nacional de Técnica Aeroespacial (INTA)
The adhesion properties of poly(glycidyl methacrylate (GMA)-co-butyl acrylate (BA)) statistical copolymers, synthesized by atom transfer radical polymerization (ATRP), are investigated employing three different curing agents or hardeners, such as diethanolamine (DEA), dicyandiamide (DICY), and 2-cyanoacetamide (2-CA) on copper, iron, brass, aluminum, and titanium metal surfaces. This work describes the treatment of the different surfaces, establishes the optimal curing conditions from differential scanning calorimetry (DSC) analysis of these novel adhesive systems, and evaluates the results of the single-lap shear test for metal joints. Thus, by dynamic DSC measurements of the mixtures, a low curing temperature of 90 °C is defined when DEA is used as a curative; while systems based on DICY and 2-CA require temperatures of 150 °C and 160 °C, respectively. In addition, the curing process of this controlled acrylic copolymer with DICY exhibits a singular behavior, possibly due to the curing reaction mechanism, where multiple epoxy-amine ring-opening polyaddition reactions take place between DICY's active hydrogens and epoxy groups of poly(GMA-co-BA). This latter curing system shows the highest adhesion features with lap-shear strength at room temperature of 15.5 MPa, using copper as metallic substrate; however, the best results are obtained using 2-CA as curing agent with aluminum and iron.
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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Al Slurry Coatings for Molten Carbonate Fuel Cell Separator Plates
(Scientific.Net, 2001-01-20) Agüero, A.; García, M. C.; Muelas Gamo, Raúl; Sánchez, A.; Pérez, Francisco J.; Duday, David; Hierro, M. P.; Gómez, Consuelo
The corrosion behaviour of Al slurry coated AISI 310 stainless steel, with and without diffusion heat treatment, was investigated as a wet seal material for molten carbonate fuel cell (MCFC) at 650°C. The results were compared with IVD Al coated AISI 310. Characterization of the samples before and after exposure to the eutectic 62 mol% Li2CO3-38 mol% K2CO3 mixture at 650°C for 1000 h by SEM-EDS and XRD was carried out. The presence of LiAlO2 on the coated samples was confirmed by XRD. The slurry Al-coated stainless steels performed at least as well as the IVD Al coating.
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Analytic adjoint solution for incompressible potential flows
(AIP Publishing, 2025-06-10) Lozano, Carlos; Ponsin, J.; Ponsin Roca, Jorge; Instituto Nacional de Técnica Aeroespacial (INTA)
We obtain the analytic adjoint solution for two-dimensional incompressible potential flow for a cost function measuring aerodynamic force using the connection of the adjoint approach to Green's functions and also by establishing and exploiting its relation to the adjoint incompressible Euler equations. By comparison with the analytic solution, it is shown that the naïve approach based on solving Laplace's equation for the adjoint variables can be ill-defined. The analysis of the boundary behavior of the analytic solution is used to discuss the proper formulation of the adjoint problem as well as the mechanism for incorporating the Kutta condition in the adjoint formulation.
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Analytic adjoint solutions for the 2-D incompressible Euler equations using the Green's function approach
(Cambridge University Press, 2022-06-13) Lozano, Carlos; Ponsin, J.; Ponsin Roca, Jorge; Instituto Nacional de Técnica Aeroespacial (INTA)
The Green's function approach of Giles and Pierce (J. Fluid Mech., vol. 426, 2001, pp. 327–345) is used to build the lift and drag based analytic adjoint solutions for the two-dimensional incompressible Euler equations around irrotational base flows. The drag-based adjoint solution turns out to have a very simple closed form in terms of the flow variables and is smooth throughout the flow domain, while the lift-based solution is singular at rear stagnation points and sharp trailing edges owing to the Kutta condition. This singularity is propagated to the whole dividing streamline (which includes the incoming stagnation streamline and the wall) upstream of the rear singularity (trailing edge or rear stagnation point) by the sensitivity of the Kutta condition to changes in the stagnation pressure.
Acceso Abierto
Breakup criterion for droplets exposed to the unsteady flow generated by an incoming aerodynamic surface
(Elsevier, 2020-03-15) López Gavilan, Pablo; Velázquez, Ángel; García Magariño, A.; Sor, Suthyvann; Sor, Suthyvann; Instituto Nacional de Técnica Aeroespacial (INTA); Ministerio de Economía y Competitividad (MINECO)
An experimental and theoretical study is presented on the problem of droplet breakup exposed to a continuously accelerating flow generated by an incoming aerodynamics surface. Droplet breakup experiments were carried out in a rotating arm facility. Droplet diameters were of the order of 1 mm. The maximum velocity of the airfoils located at the end of the rotating arm was 90 m/s. Droplet deformation was computed using a phenomenological model developed previously by the authors. The dynamics of this deformation was coupled to an instability model based on the growth of Rayleigh-Taylor waves at the droplet surface. It was found that, within the experimental uncertainty, breakup occurs when the instability wavelength approaches the droplet hydraulic diameter assuming that it flattens and deforms as an oblate spheroid. This fact allowed for the generation of a theoretical closed-form droplet deformation and breakup model that predicts the onset of breakup with discrepancies of about ±10 % when compared to the experimental results. Finally, as an application case, this closed-form model is used to simulate an actual situation in which the objective is to investigate whether a series of droplets that are approached by an airfoil either impact on its surface, or break prior to collision, or break without colliding, or pass through undamaged.
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Catalytic effects over formation of functional thermoplastic elastomers for rocket propellants
(Wiley, 2021-11-22) Lucio, B.; De la Fuente, J. L.; Ministerio de Ciencia e Innovación (MICINN); Instituto Nacional de Técnica Aeroespacial (INTA); Gobierno Vasco
Rheometry was the main method to characterize the curing process of binders made of functional polyurethanes (PUs). The macroglycols characterization by means of additional techniques such as nuclear magnetic resonance, size exclusion chromatography and differential scanning calorimetry, provided further information for the chemorheological description. Materials were based on Butacene ((ferrocenylbutyl)dimethylsilane grafted to hydroxyl-terminated polybutadiene (HTPB)), used in the solid propulsion field. First, the flow parameters for the uncured reactive mixtures of Butacene and four different diisocyanates were analysed via viscometry and these were markedly influenced by the chemical structure of the curing agents. Analysing the rheokinetic constant values of the pre-gel stage for Butacene- and HTPB-reactive systems, relevant catalysis caused by the ferrocene moiety was detected when aliphatic reactants were used, such as isophorone diisocyanate or 1,6-hexamethylene diisocyanate (IPDI and HMDI, respectively). No catalytic effect was found for 2,4-toluene diisocyanate (2,4-TDI) or even for 4,4’-methylenediphenyl diisocyanate (4,4’-MDI). Finally, the use of dynamic rheology was useful to evaluate the critical points during gelation process, where the reactivity of curing agents was associated with the achievement of elastic properties. Both techniques agreed the reactivity order of curing agents with Butacene, which is 4,4’-MDI > HMDI >> 2,4-TDI ≥ IPDI. The knowledge of the structure-reactivity relationship and, moreover, the kinetics of the urethane network formation for these metallo-PUs is paramount in manufacturing processes for advanced thermoplastic elastomer applications.
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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
Comparison between pilot and lab scale testing of aluminide coated and uncoated ferritic steels under oxy-fuel and coal/thistle co-firing conditions
(Elsevier, 2022-11-25) Gutiérrez, M.; Illana, Andrea; Bahillo, Alberto; Benito, Manuel J.; García Martín, G.; Pérez Trujillo, Francisco Javier; Agüero, A.; European Commission (EC); Universidad Complutense de Madrid(UCM)
The present study compares the biomass corrosion behavior of two diffusion aluminide coating obtained by slurry application, which were deposited on two low-chromium content steels, ferritic-martensitic P92 (8.7 wt% Cr) and ferritic T22 (2 wt% Cr). Their performance degradation was conducted under an oxy-fuel combustion environment for both coated and uncoated materials both under laboratory conditions and in a pilot plant burning thistle for 500 h. Exposures were carried out in the laboratory at two different temperatures, 600 °C and 650 °C, under a model atmosphere consisting of 60 % CO2, 30 % H2O, 8 % O2, bal.% N2 (in vol%), 500 vppm HCl and 2 vppm SO2. The pilot plant used a mixed fuel of 60 wt% coal and 40 wt% thistle that was burnt and the samples were exposed to a temperature range of 600–620 °C. After testing, the results revealed that the aluminide-coated materials exhibited a very high resistance under both extreme scenarios, with a variable protective character related to their Al content. On the contrary, uncoated material exhibited severe degradation, in particular T22. Microstructural and morphological studies showed up similar corrosion patterns and products on coated and uncoated materials for both testing environments.
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Comparison of descaling methods to study the corrosion kinetics of ferritic steels after dynamic exposure to molten carbonates
(Elsevier, 2022-12-24) Audigié, P.; Rodríguez, Sergio; Agüero, A.; Pedrosa, Fátima; Paiva, Teresa; Diamantino, Teresa C.
T91 ferritic-martensitic steel was exposed to Li, Na and K molten carbonates at 650ºC under dynamic conditions up to 1000 h. After testing, three descaling methods, two from the ISO8407 and one from the ISO17245 standards were applied to remove the corrosion products and determine the corrosion rates. The two ISO8407 methods were more appropriate although the procedure required several steps to fully remove the corrosion products. The ISO17245 method led to a higher mass loss affecting probably the base material. Oxides identification was performed by XRD following step by step layers removal. Li-, Na-, K-containing oxides and chromates/chromites were detected.
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Corrosion study of a water filter
(Elsevier, 2022-07-22) Valles González, M. P.; Pastor Muro, Ana; García Martínez, María; Instituto Nacional de Técnica Aeroespacial (INTA)
A water filter was inspected in order to determine the origin and chemical nature of several corrosion products on its surface. The metallic material base was analyzed to be a lead brass with a nickel coating of 4–5 µm thickness. The plastic base, as well as the rod and nut, was impregnated by similar deposits whose chemical nature was mainly oxides, carbonates and chlorides, according to the EDX analysis. Some white deposits were observed in the nut and rod, probably corresponding to zinc oxide. These deposits may be formed upstream by the pipe materials or the sediments that the fluid may carried inside the pipe. The absence of a nickel coating leaded to corrosion pits in some areas of the rod and nut. This corrosion has initiated on the surface, and has progressed through the beta phase that was zinc impoverished, to the inner zone of the filter.
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Cyclic oxidation and mechanical behaviour of slurry aluminide coatings for steam turbine components
(Elsevier, 2007-04-02) Agüero, A.; Muelas Gamo, Raúl; Gutiérrez, Marcos; Van Vulpen, R.; Osgerby, Steve; Banks, J. P.
The excellent steam oxidation resistance of iron aluminide coatings on ferritic steels at 650 °C has been demonstrated both by laboratory tests and field exposure. These coatings are formed by the application of an Al slurry followed by diffusion heat treatment at 700 °C for 10 h. The resulting microstructure is mostly composed of Fe2Al5 on top of a much thinner FeAl layer. This coating exhibits perpendicular cracks due to thermal expansion mismatch between coating and substrate. However, these stress relieving cracks do not seem to have an effect on the mechanical properties of the substrate. Cyclic oxidation, creep resistance and TMF testing of these coatings at 650 °C indicate excellent performance.
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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Differential iron management in monocotyledon and dicotyledon plants from the Río Tinto basin.
(Springer Link, 2020-01-06) De la Fuente, V.; Rufo, L.; Rodríguez, N.; Ramírez, E.; Sánchez Gavilán, I.; Amils Pibernat, R.; Rodríguez Rivas, Noé; Ministerio de Economia Industria y Competitividad (MINECO); 0000-0002-2239-6523
The study of plants adapted to an extreme environment with a high concentration of iron such as Río Tinto allowed the study of important elements for the development and control of plant growth including their localization, management, and storage. The absorption, transport, and accumulation of iron were studied in different species of dicotyledons (Sarcocornia pruinosa, Salicornia patula, Arthrocnemum macrostachyum, and Halogeton sativus of the Chenopodiaceae family) and monocotyledons (Imperata cylindrica, Cynodon dactylon, and Panicum repens from the Poaceae family), all obtained from the Río Tinto banks in different sample collection campaigns. The results clearly show that phytoferritin is not observed in the chloroplast of monocotyledons, an important difference from what is observed in dicotyledons. The presence of plastids with a high concentration of iron in the sieve tubes of monocotyledons strongly suggests their possible role in the transport and accumulation of iron in these plants.
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Droplet breakup criterion in airfoils leading edge vicinity
(Aerospace Research Central, 2018-05-07) García Magariño, A.; Sor, Suthyvann; Velázquez, Ángel; Sor, Suthyvann; Instituto Nacional de Técnica Aeroespacial (INTA); Ministerio de Economía y Competitividad (MINECO)
A new breakup criterion is proposed in this paper for droplets subject to the flowfield generated by an incoming airfoil (that is, the criterion should be applied only to this type of aerodynamics flow). This criterion is based on the study of the characteristic times involved in the problem. These are the characteristic external flowfield variation time and the characteristic droplet deformation time. The criterion takes the shape of an empirical correlation that relates the Weber number at the onset of the breakup to the external flowfield and droplet characteristics. Experimental data on the droplet deformation and breakup tests conducted in a rotating arm facility are used to generate the data used to develop the correlation. Droplets, with diameters in the range of 0.3–3.6 mm, are allowed to fall in the path of an incoming airfoil attached to the end of a rotating arm. Airfoil velocities vary between 50 and 90 m∕s. The airfoil leading-edge radius varies from 0.030 to 0.103 m. Experiments are recorded with a high-speed camera using the shadowgraph illumination technique. The empirical breakup correlation applies to droplets that break in the bag and stamen mode. Some additional limited data on droplets that break in the bag and the shear mode are analyzed to see how they fit into the correlation.

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