Persona: de Lucas Veguillas, Javier
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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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de Lucas Veguillas
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Javier
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Publicación Restringido Numerical optimization of the radial dependence of effective emissivity in blackbody cylindrical cavities(IOP Science Publishing, 2014-06-25) de Lucas Veguillas, JavierThe effective emissivity of a blackbody with cylindrical geometry has a definite radial dependence, at the bottom cavity, which is a function of the surface intrinsic emissivity, cavity geometry (L/D) and the temperature gradient along the cylinder walls. The optimal use of large aperture blackbody cavities, particularly in thermal imager calibration applications or for the characterization of size-of-source effect of radiation thermometers for example, requires quite precise control of the thermal gradient, in order to achieve sources as uniform as possible in effective emissivity, over the complete aperture. In this paper, we present a numerical model in which the radial profile of effective emissivity is optimized, by means of the theoretical modification of the temperature gradients in a cylindrical diffuse cavity. The distribution functions of secondary absorption impacts are defined and the criteria for a suitable choice of experimentally realizable temperature gradients are presented, including the uncertainty analysis.Publicación Restringido Measurement and analysis of the temperature gradient of blackbody cavities, for use in radiation thermometry(Springer Link, 2018-03-24) de Lucas Veguillas, Javier; Segovia, José Juan; Instituto Nacional de Técnica Aeroespacial (INTA)Blackbody cavities are the standard radiation sources widely used in the fields of radiometry and radiation thermometry. Its effective emissivity and uncertainty depend to a large extent on the temperature gradient. An experimental procedure based on the radiometric method for measuring the gradient is followed. Results are applied to particular blackbody configurations where gradients can be thermometrically estimated by contact thermometers and where the relationship between both basic methods can be established. The proposed procedure may be applied to commercial blackbodies if they are modified allowing secondary contact temperature measurement. In addition, the established systematic may be incorporated as part of the actions for quality assurance in routine calibrations of radiation thermometers, by using the secondary contact temperature measurement for detecting departures from the real radiometrically obtained gradient and the effect on the uncertainty. On the other hand, a theoretical model is proposed to evaluate the effect of temperature variations on effective emissivity and associated uncertainty. This model is based on a gradient sample chosen following plausible criteria. The model is consistent with the Monte Carlo method for calculating the uncertainty of effective emissivity and complements others published in the literature where uncertainty is calculated taking into account only geometrical variables and intrinsic emissivity. The mathematical model and experimental procedure are applied and validated using a commercial type three-zone furnace, with a blackbody cavity modified to enable a secondary contact temperature measurement, in the range between 400 °C and 1000 °C.Publicación Restringido Geometrical and thermal optimization of cylinder-conical blackbody cavities to uniform radiance temperature profiles in the infrared(Elsevier, 2023-04-07) de Lucas Veguillas, Javier; Segovia, José Juan; Instituto Nacional de Técnica Aeroespacial (INTA)Large-area blackbody cylinder conical cavities are generally used as primary radiation sources for calibrating and characterizing radiation thermometers and quantitative thermal imagers in the infrared, both in metrology laboratories or for industrial applications. The radiation temperature of the emitted radiation depends on effective emissivity and surface (contact) temperature. The instrument’s field of view generally only covers the cavity bottom since this is where contact temperature is best measured. A non-uniform effective emissivity profile at the bottom poses a problem if instruments with a different field of view have to be calibrated with the same blackbody. Spatial uniformity depends principally on the cone angle and temperature gradient along the cavity. In this paper, we analyse blackbody optimization in terms of uniform radiance temperature profiles as a function on geometric parameters and temperature. For the isothermal case, we conclude that angles between 160° and 170° are the optimum, depending on intrinsic emissivity and length-to-diameter ratio of the cavity. For non-isothermal cavities, the effect of the temperature gradient on uniformity is relatively small, with only the temperature near the bottom proving significant. The use of multi-zone maintenance furnaces would allow temperature gradients to be designed that can improve uniformity in addition to geometric optimization.Publicación Restringido Evaluation of a Portable Apparatus for the Realization of the Triple Point of Argon(Springer Link, 2014-06-21) de Lucas Veguillas, Javier; Benyon Puig, RobertIn this paper, the evaluation of the performance of a portable triple-point-of-argon apparatus, via the analysis of the calibration history of selected working (fused silica) standard platinum resistance thermometers (SPRTs), is presented. These have an extensive calibration history, both internally (using different apparatus) and externally at two National Measurement Institutes. A special procedure had to be developed, for the calibration of metal-sheathed SPRTs, in order to ensure adequate thermal contact between the SPRT and the well and to minimize the influence of stem conduction, inherent in the compact design of the maintenance system. The results show good agreement between the measurements performed with this system and those with the previously used apparatus, to a level of uncertainty consistent with the INTA calibration and measurement capability (CMC) of 3.0 mK (k = 2). This CMC is given by the Spanish accreditation body (ENAC), under accreditation No. 16/10.007, for the routine calibration of SPRTs at the triple point of argon. It is concluded that the portable apparatus is suitable for use as a transfer standard for the comparison of local realizations of the triple point of argon. This avoids the need to shipping fragile SPRTs, with a valuable long calibration history, and eliminates the contributions due the long-term stability of the thermometers subjected to transportation. The long-term stability of the portable apparatus reported in this work has only been determined in laboratory conditions.Publicación Restringido A simple geometrical model for calculation of the effective emissivity in blackbody cylindrical cavities(Springer Link, 2015-10-15) de Lucas Veguillas, Javier; Instituto Nacional de Técnica Aeroespacial (INTA)A simple geometrical model for calculating the effective emissivity in blackbody cylindrical cavities has been developed. The back ray tracing technique and the Monte Carlo method have been employed, making use of a suitable set of coordinates and auxiliary planes. In these planes, the trajectories of individual photons in the successive reflections between the cavity points are followed in detail. The theoretical model is implemented by using simple numerical tools, programmed in Microsoft Visual Basic for Application and Excel. The algorithm is applied to isothermal and non-isothermal diffuse cylindrical cavities with a lid; however, the basic geometrical structure can be generalized to a cylindro-conical shape and specular reflection. Additionally, the numerical algorithm and the program source code can be used, with minor changes, for determining the distribution of the cavity points, where photon absorption takes place. This distribution could be applied to the study of the influence of thermal gradients on the effective emissivity profiles, for example. Validation is performed by analyzing the convergence of the Monte Carlo method as a function of the number of trials and by comparison with published results of different authors.Publicación Restringido Aperturas efectivas en calibración y comparación de termómetros de radiación(Federación de Asociaciones de Ingenieros Industriales de España, 2020-09-15) de Lucas Veguillas, Javier; Instituto Nacional de Técnica Aeroespacial (INTA)Los termómetros de radiación (TR) se calibran con cuerpos negros (CN) cuya apertura debe cubrir suficientemente el blanco nominal del termómetro. Debido a posibles imperfecciones en su sistema óptico, radiación proveniente de regiones exteriores al blanco puede llegar al detector. Es el efecto del tamaño de la fuente (ETF) y constituye una limitación importante en el uso de TR en aplicaciones especialmente en un entorno industrial y fuente entre otras de incertidumbre de medida.Publicación Restringido Uncertainty calculation of the effective emissivity of cylinder-conical blackbody cavities(IOP Science Publishing, 2015-12-30) de Lucas Veguillas, Javier; Segovia, José Juan; Instituto Nacional de Técnica Aeroespacial (INTA)A numerical and geometrical model for calculating the local effective emissivity of isothermal blackbody cylinder-conical cavities with lid, assuming diffuse reflection, is described. This has been developed by generalizing previous models based on conical and cylindrical geometries. The model has been validated by determining the diffusely reflected photon trajectories and the corresponding experimental view factors between given pairs of surface elements. Differences compared to theoretical values, were subsequently analyzed in terms of the model's intrinsic uncertainty. A well-defined numerical function that calculates the effective emissivity as a function of its natural variables, intrinsic emissivity and geometrical parameters, is established. In order to calculate the probability distribution of the output quantity, we use the Monte Carlo method for the propagation of the probability distributions that characterize our knowledge concerning the values of the influence variables. The model is applied to heat-pipe black bodies installed at our laboratory, previously characterized at the PTB. A comparison with published uncertainty results, obtained by applying classical uncertainty propagation techniques, is also made.Publicación Restringido Practical Calibration of Platinum Resistance Thermometers in the Range −190 °C to 0 °C(Springer Link, 2011-10-22) de Lucas Veguillas, Javier; Benyon Puig, RobertThe results obtained in the characterization of a low-temperature comparator and its performance in relation to the calibration of metal and borosilicate sheathed standard platinum resistance thermometers (SPRTs) calibrated at the International Temperature Scale of 1990 (ITS-90) fixed points, are presented and discussed. The principal influence quantities are addressed and the estimation of measurement uncertainty supporting the calibration and measurement capability (CMC) accredited by Entidad Nacional de Acreditación (ENAC), the Spanish Accreditation Body, are presented and discussed.Publicación Restringido Validation of a geometrical model for the calculation of the integrated effective emissivity of conical cavities with a lid(IOP Science Publishing, 2015-08-03) de Lucas Veguillas, Javier; Instituto Nacional de Técnica Aeroespacial (INTA); Ministerio de Ciencia e Innovación (MICINN)In this paper, a geometrical model for the numerical calculation of the integrated effective emissivity of conical isothermal cavities with a lid, is described in detail. We make use of the Montecarlo method and the 'back ray tracing' technique, assuming diffuse reflection and a detector situated at an arbitrary distance from the cavity aperture. First, the geometry of the problem is discussed and the local hemispherical emissivity profiles along the cone generatrix are calculated for different configurations. Then we proceed to the validation of the model, by calculating the distribution of the reflected photons in the interior of the cavity, such as it is provided by the numerical algorithm. The calculated distribution is compared with theoretical values, obtained from the expressions of the view factors for the conical geometry. The calculated values for the local and integrated effective emissivity are compared with results published by other authors, highlighting the differences between them, and the internal consistency of our model is demonstrated. Special attention to the calculation of the view factors in conical cavities affected by vignetting due to the obstruction produced by the lid, is paid. The view factors of points at the penumbral region are numerically calculated, applying the Montecarlo method, including a complete analysis of the uncertainty.Publicación Acceso Abierto In-flight calibration of the MEDA-TIRS instrument onboard NASA's Mars2020 mission(Elsevier, 2024-11-09) Sebastián, E.; Martínez, Germán M.; Ramos, Miguel; Smith, Michael D.; Peinado, V.; Mora Sotomayor, L.; Lemmon, M. T.; Vicente Retortillo, Álvaro; de Lucas Veguillas, Javier; Ferrándiz, Ricardo; Rodríguez Manfredi, J. A.This article describes a novel procedure and algorithm used for the in-flight calibration of the Thermal Infrared Sensor (TIRS) onboard the Mars 2020 mission. The purpose is to recalibrate the responsivity of TIRS’ IR detectors as they degrade following surface operations and exposure to harsh environmental conditions. Using data from in-flight calibration campaigns conducted through sol 800 of this mission, we report the time evolution of the responsivity for the different IR detectors, as well as the final performance achieved by the algorithm in the real operating environment. Moreover, we analyzed changes in responsivity as a function of TIRS geometric design and environmental factors, e.g., detector orientation, direct exposure to prevailing winds and solar radiation, electrostatic properties of the detector filter, and atmospheric dust concentration. We concluded that dust deposition on the detectors' filter during landing, and later during operation is the most likely cause of the degradation observed in the various channels, with gravitational sedimentation and the capacity of the filters to accumulate electrostatic charge being key factors. The relative and absolute degradation of the TIRS is similar to those reported by other Martian missions and instruments with similar orientations, and to date, it has shown no signs of cleaning after more than a year on the surface of Mars. Accounting for changes in responsivity during the mission is critical to maintaining the reliability of TIRS measurements, which will later be made available in NASA's Planetary Data System for the benefit of the scientific community.
