National Institute of Aerospace Technology INTA

Torrejón de Ardoz, Spain

National Institute of Aerospace Technology INTA

Torrejón de Ardoz, Spain
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Garcia-Magarino A.,Defense Systems | Sor S.,National Institute of Aerospace Technology INTA | Velazquez A.,Technical University of Madrid
9th AIAA Atmospheric and Space Environments Conference, 2017 | Year: 2017

A new breakup criterion is proposed in this article for droplets that suffer the flow field generated by an incoming airfoil. This criterion is based on the study of the characteristic times involved in the problem, which are the characteristic flow field variation time and the characteristic droplet deformation time. An empirical correlation is given to determine the Weber number at the onset of the breakup for each flow field and droplet size. Experimental data on the droplet deformation and breakup tests conducted in a rotating arm facility was used for the correlation. Droplets, in the range of 0.3 to 3.6 mm of diameter, were allowed to fall in the path of an incoming airfoil attached to the end of a rotating arm. Airfoil velocities varied between 50 m/s and 90 m/s while its leading edge radius ranged from 0.030 to 0.103 m. The phenomenon was recorded by a high speed camera using shadowgraph illumination technique. The empirical correlation was obtained from droplets that breakup in the bag and stamen breakup mode. However the same correlation seems to be valid for droplets in the regime of shear breakup and for droplets in the regime of bag breakup. © 2017, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

Adame J.A.,National Institute of Aerospace Technology INTA | Adame J.A.,University of Huelva | Serrano E.,Complutense University of Madrid | Bolivar J.P.,University of Huelva | de la Morena B.A.,National Institute of Aerospace Technology INTA
Journal of Applied Meteorology and Climatology | Year: 2010

It is well established that surface ozone levels are greatly affected by orography, solar radiation intensity, meteorological conditions, and the levels of their precursors. In this work, the authors study the sea-land breeze circulation in its relation with the behavior of ozone in a coastal area, located in southwestern Europe, with high levels of solar radiation and an important industrial complex emitting air pollutants. Hourly mean data over a 7-yr period (1999-2005) have been used in the study. Two patterns of sea-land breeze have been identified after analyzing 2298 days of measurements: a "pure" breeze (179 cases) and another one, called a "nonpure" breeze (284 cases), which is the resulting flow of the former and northwesterlies synoptic forcing. Among other results, the highest levels of surface ozone were observed under pure sea-land breeze, with hourly values up to 100 μg m-3 in the mean daily evolution. In contrast, for a nonpure breeze, the 24-h average daily value was lower than the corresponding one under a pure breeze by a factor of 1.16 and could reach 1.60 in representative real cases. These findings give evidence that the formation and accumulation of ozone are favored by the conditions under a pure sea-land breeze: that is, perpendicular wind directions toward the coastline, effective recirculation of air masses, and formation of ozone residual layers above the sea. Because these atmospheric conditions occur in other coastal regions in the world, the conclusions of this study could be extended to them. © 2010 American Meteorological Society.

Carnero J.A.A.,National Institute of Aerospace Technology INTA | Bolivar J.P.,University of Huelva | de la Morena B.A.,National Institute of Aerospace Technology INTA
Environmental Science and Pollution Research | Year: 2010

Introduction: Photochemical ozone pollution of the lower troposphere (LT) is a very complex process involving meteorological, topographic emissions and chemical parameters. Ozone is considered the most important air pollutant in rural, suburban and industrial areas of many sites in the world since it strongly affects human health, vegetation and forest ecosystems, and its increase during the last decades has been significant. In addition, ozone is a greenhouse gas that contributes to climate change. For these reasons, it is necessary to carry out investigations that determine the behaviour of ozone at different locations. The aim of this work is to understand the levels and temporal variations of surface ozone in an industrial-urban region of the Southwest Iberian Peninsula. Materials and methods: The study is based on ozone hourly data recorded during a 6-year period, 2000 to 2005 at four stations and meteorological data from a coastal station. The stations used were El Arenosillo and Cartaya-both coastal stations, Huelva-an urban site and Valverde-an inland station 50 km away from the coastline. The general characteristics of the ozone series, seasonal and daily ozone cycles as well as number of exceedances of the threshold established in the European Ozone Directive have been calculated and analysed. Results: Analysis of the meteorological data shows that winter-autumn seasons are governed by the movement of synoptic weather systems; however, in the spring-summer seasons, both synoptic and mesoescale conditions exist. Average hourly ozone concentrations range from 78.5 ± 0.1 μg m-3 at Valverde to 57.8 ± 0.2 μg m-3 at Huelva. Ozone concentrations present a seasonal variability with higher values in summer months, while in wintertime, lower values are recorded. A seasonal daily evolution has also been found with minimum levels around 08:00 UTC, which occurs approximately 1-1.5 h after sunrise, whereas the maximum is reached at about 16:00 UTC. Furthermore, during summer, the maximum value at El Arenosillo and Valverde stations remains very uniformed until 20:00 UTC. These levels could be due to the photochemical production in situ and also to the horizontal and vertical ozone transport at El Arenosillo from the reservoir layers in the sea and in the case of Valverde, the horizontal transport, thanks to the marine breeze. Finally, the data have been evaluated relative to the thresholds defined in the European Ozone Directive. The threshold to protect human health has been exceeded during the spring and summer months mainly at El Arenosillo and Valverde. The vegetation threshold has also been frequently exceeded, ranging from 131 days at Cartaya up to 266 days at Valverde. Discussion: The results in the seasonal and daily variations demonstrate that El Arenosillo and Valverde stations show higher ozone concentrations than Cartaya and Huelva during the spring and summer months. Under meteorological conditions characterized by land-sea breeze circulation, the daytime sea breeze transports the emissions from urban and industrial sources in the SW further inland. Under this condition, the area located downwind to the NE is affected very easily by high ozone concentrations, which is the case for the Valverde station. Nevertheless, according to this circulation model, the El Arenosillo station located at the coast SE from these sources is not directly affected by their emissions. The ozone concentrations observed at El Arenosillo can be explained by the ozone residual layer over the sea, similar to other coastal sites in the Mediterranean basin. Conclusions: The temporal variations of the ozone concentrations have been studied at four measurement sites in the southwest of the Iberian Peninsula. The results obtained point out that industrial and urban emissions combined with specific meteorological conditions in spring and summer cause high ozone levels which exceed the recommended threshold limits and could affect the vegetation and human health in this area. Recommendations and perspectives: This work is the first investigation related to surface ozone in this region; therefore, the results obtained may be a useful tool to air quality managers and policy-makers to apply possible air control strategies towards a reduction of ozone exceedances and the impact on human health and vegetation. Due to the levels, variability and underlying boundary layer dynamics, it is necessary to extend this research in this geographical area with the purpose of improving the understanding of photochemical air pollution in the Western Mediterranean Basin and in the south of the Iberian Peninsula. © Springer-Verlag 2009.

Hernandez-Ceballos M.A.,University of Huelva | Hernandez-Ceballos M.A.,National Institute of Aerospace Technology INTA | Adame J.A.,National Institute of Aerospace Technology INTA | Bolivar J.P.,University of Huelva | De la Morena B.A.,National Institute of Aerospace Technology INTA
Meteorology and Atmospheric Physics | Year: 2013

Air masses are characterized by physical (temperature, humidity) and chemical (transported gases and aerosols) properties, being associated their arrival to different meteorological scenarios. The knowledge of the air masses over a region is fundamental as complementary information in several atmospheric studies, being the calculation of back-trajectory the most widely used tool whenever air masses are analyzed. A study of air masses has been carried out in southwestern Iberian Peninsula using 5-day kinematic back trajectories computed by the HYSPLIT model at three heights (500, 1,500 and 3,000 m) from 1997 to 2007. The main aims have been to characterize their vertical behaviour and their thermal and humidity properties. Thirteen trajectory clusters have been defined, showing the northerly and westerly clusters a high coupling degree. Seasonal daily variation of potential temperature and specific humidity has been analyzed, obtaining higher differences among clusters in the cold season. © 2012 Springer-Verlag Wien.

Magdaleno S.,National Institute of Aerospace Technology INTA | Magdaleno S.,Complutense University of Madrid | Herraiz M.,Complutense University of Madrid | Radicella S.M.,Abdus Salam International Center For Theoretical Physics
IEEE Transactions on Geoscience and Remote Sensing | Year: 2012

A new postprocessing technique has been developed to detect and characterize equatorial plasma bubbles (EPBs) from slant total electron content values calculated from GPS observations. The technique identifies an EPB when a slant total electron content depletion is detected. This technique is based on the analysis of the slope and the population variance variations of the slant total electron content values. The Ionospheric Bubble Seeker, based on the Java programming language, has been developed to implement this technique, allowing its use in all operating systems and on the Internet. Several thousands of slant total electron content profiles from different stations around the equatorial region have been analyzed to configure it. Different stations distributed worldwide have been analyzed to evaluate the robustness of the technique. The results reveal a clear daily dependence, showing the influence of the seasonal, longitudinal, and solar activity conditions. These results are compared with previous studies accomplished from different techniques and measurements and show clear agreements in the results. © 2012 IEEE.

Medina S.F.,CSIC - National Center for Metallurgical Research | Gomez M.,CSIC - National Center for Metallurgical Research | Valles P.,National Institute of Aerospace Technology INTA
Steel Research International | Year: 2010

Recrystallisation kinetics of two low-carbon steels, of which one with Ti and the other with Al as precipitate-forming elements was studied by means of hot torsion tests. The mean size of TiN and AlN particles that precipitate during hot deformation was analysed by transmission electron microscopy (TEM). These results, along with the determination of the activation energy, the precipitated volume fraction and the diffusion coefficients of Ti, Al and N in austenite explain the ineffectiveness of these particles to inhibit the static recrystallisation. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dufour J.,Rey Juan Carlos University | Serrano D.P.,Rey Juan Carlos University | Galvez J.L.,National Institute of Aerospace Technology INTA | Gonzalez A.,National Institute of Aerospace Technology INTA | And 2 more authors.
International Journal of Hydrogen Energy | Year: 2012

New processes under development for producing hydrogen have been assessed using a life cycle methodology and compared to conventional ones. The aim of this paper is to determine the main obstacles to be beaten or the critical aspects to be addressed to ensure the feasibility of these processes. Water photosplitting, solar two-step thermochemical cycles and automaintained methane decomposition with different lay-outs were studied. They have been compared to methane steam reforming with CCS and electrolysis with different electricity sources. The results show the good behaviour of the automaintained methane decomposition. This process is one of the best options when the greenhouse effect emissions are evaluated. Nevertheless, the consumption of a great amount of a non-renewable resource, i.e., natural gas, as reagent can be negative. The two-step thermochemical cycles based on NiFe2O4 is also an interesting option, but its behaviour depends largely on the infrastructure materials employed on the installations. The most promising option is photosplitting with CdS as catalysts. This process shows the best performance. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Dufour J.,Rey Juan Carlos University | Dufour J.,IMDEA Madrid Institute for Advanced Studies | Serrano D.P.,Rey Juan Carlos University | Serrano D.P.,IMDEA Madrid Institute for Advanced Studies | And 3 more authors.
Energy and Fuels | Year: 2011

Because of the existence of infrastructures all around the world, the use of fossil resources as raw materials for hydrogen production can be a midterm solution in the implementation of hydrogen as a transport fuel. Therefore, the fuel processing technology used for the production of hydrogen should produce the lowest amount of greenhouse gases, with the highest energy efficiency and the lowest environmental impact. In this work, several options for hydrogen production from fossil fuels are evaluated: steam reforming, autothermal reforming of hydrocarbons, coal gasification, and methane decomposition. A system for the capture of CO2 is supposed to be integrated in the reforming and gasification processes. This study evaluates the overall life cycle greenhouse gas emissions, the fossil energy consumption, and the environmental impact for the current and future energy scenarios. The autothermal reforming, decomposition of natural gas, and coal gasification are the best options from all of the points of view, while extrapolations to future scenarios predict very similar impacts. The economic analysis of methane decomposition processes reveals that the carbon selling price and the conversion of methane are the main factors influencing the cost-efficiency of produced hydrogen. © 2011 American Chemical Society.

Dufour J.,Rey Juan Carlos University | Galvez J.L.,National Institute of Aerospace Technology INTA | Serrano D.P.,Rey Juan Carlos University | Serrano D.P.,IMDEA Madrid Institute for Advanced Studies | And 2 more authors.
International Journal of Hydrogen Energy | Year: 2010

Methane decomposition to yield hydrogen and carbon (CH4 ⇆ 2H2 + C) is one of the cleanest alternatives, free of CO2 emissions, for producing hydrogen from fossil fuels. This reaction can be catalyzed by metals, although they suffer a fast deactivation process, or by carbonaceous materials, which present the advantage of producing the catalyst from the carbon obtained in the reaction. In this work, the environmental performance of methane decomposition catalyzed by carbonaceous catalysts has been evaluated through Life Cycle Assessment tools, comparing it to other decomposition processes and steam methane reforming coupled to carbon capture systems. The results obtained showed that the decomposition using the autogenerated carbonaceous as catalyst is the best option when reaction conversions higher than 65% are attained. These were confirmed by 2015 and 2030 forecastings. Moreover, its environmental performance is highly increased when the produced carbon is used in other commercial applications. Thus, for a methane conversion of 70%, the application of 50% of the produced carbon would lead to a virtually zero-emissions process. © 2009 Professor T. Nejat Veziroglu.

Garcia-Magarino A.,Defense Systems | Sor S.,National Institute of Aerospace Technology INTA | Velazquez A.,Technical University of Madrid
Experimental Thermal and Fluid Science | Year: 2016

The work presented in this article describes a data reduction method for droplet deformation experiments carried out in a rotating arm facility. The reduction method is based on the technique known as High Order Singular Value Decomposition (HOSVD). The idea is to find out whether, in this context, HOSVD allows for sufficient generalization of the results in a way that the outcome of new cases can be reasonably predicted with no need for further experiments. Droplets were generated and allowed to cross the path of an incoming airfoil attached to a rotating arm. A high speed camera was used to record droplet deformation as a function of time. The flow field was characterized via Particle Image Velocimetry. Airfoil velocity was varied between 50 m/s and 90 m/s. Droplet radius was in the range from 200 μm to 600 μm. Three different self-similar airfoils were used in the experiments with leading edge radii varying from 0.030 m to 0.103 m. The generated droplet deformation data was organized in the shape of a tensor having four dimensions: airfoil velocity, airfoil leading edge radius, droplet size, and time along droplet trajectory. The results obtained show that, in this problem, HOSVD can be reasonably used to densify the original experimental data tensor with acceptable accuracy. Thereby, allowing for the generation of reliable new information without having to perform additional experiments. © 2016 Elsevier Inc.

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