L'AIRE - Laboratori Aeronàutic i Industrial de Recerca i Estudis
http://hdl.handle.net/2117/3480
2017-10-20T13:42:58ZNonlinear loads model for harmonics flow prediction, using multivariate regression
http://hdl.handle.net/2117/108748
Nonlinear loads model for harmonics flow prediction, using multivariate regression
Lamich Arocas, Manuel; Balcells Sendra, Josep; Corbalán Fuertes, Montserrat; Griful Ponsati, Eulàlia
This paper describes a method for obtaining a model of a single or a set of nonlinear loads (NLL) connected to a certain point of an electrical network. The basic assumption is that the network supplying the NLL has significant series impedances and is disturbed by other parallel, random, and unknown neighbor loads, sharing part of the supply system with the NLL. The main interest for obtaining the model is its further use to predict the amount and flow of harmonic currents generated by the NLL, in the case of adding a filter to reduce the harmonics distortion. The modeling technique used in the paper is based on multivariate multiple outputs regression and leads to a set of equations giving the NLL behavior (one for each of the harmonic currents). The model is obtained from data taken at measuring point and is only valid to predict the NLL behavior when new loads are connected at this point. The modeling method was first tested with V, I data coming from simulations using a MATLAB-Simulink SimPowerSystems toolbox. Finally, the method has been validated using V, I data taken in a real installation with different neighbor loads and under different load conditions.
2017-10-17T12:00:15ZLamich Arocas, ManuelBalcells Sendra, JosepCorbalán Fuertes, MontserratGriful Ponsati, EulàliaThis paper describes a method for obtaining a model of a single or a set of nonlinear loads (NLL) connected to a certain point of an electrical network. The basic assumption is that the network supplying the NLL has significant series impedances and is disturbed by other parallel, random, and unknown neighbor loads, sharing part of the supply system with the NLL. The main interest for obtaining the model is its further use to predict the amount and flow of harmonic currents generated by the NLL, in the case of adding a filter to reduce the harmonics distortion. The modeling technique used in the paper is based on multivariate multiple outputs regression and leads to a set of equations giving the NLL behavior (one for each of the harmonic currents). The model is obtained from data taken at measuring point and is only valid to predict the NLL behavior when new loads are connected at this point. The modeling method was first tested with V, I data coming from simulations using a MATLAB-Simulink SimPowerSystems toolbox. Finally, the method has been validated using V, I data taken in a real installation with different neighbor loads and under different load conditions.Fluidic actuator performance variation via internal dimensions modifications
http://hdl.handle.net/2117/107732
Fluidic actuator performance variation via internal dimensions modifications
Baghaei, Masoud; Bergadà Granyó, Josep Maria; Campo Sud, David del
When aimed to modify the downstream vortex shedding of a given bluff body, whether any road vehicle or wing profile, the use of Active Flow Control (AFC) appears to be an efficient technology. Among the different (AFC) methodologies the use of periodic forcing is ment to have better efficiency since it requires less energy to activate the shear layer, the reason behind this efficiency lies on the fact that periodic forcing interacts with the shear layer natural instabilites. In the present paper, one of the devices widely emloyed to generate pulsating flow, is carefully studied via 3D-CFD and using OpenFOAM. Initially the base flow is being determined and compared with previous experimental results, in a second step several internal dimensions of the fluidic actuator are being modified to characterize the output frequency and amplitude variations, among the conclusions obtained it is found that a given fluidic actuator is capable of generating several output frequencies and amplitudes when modifying some internal dimensions while maintaining a constant incoming flow Reynolds number.
2017-09-18T12:43:44ZBaghaei, MasoudBergadà Granyó, Josep MariaCampo Sud, David delWhen aimed to modify the downstream vortex shedding of a given bluff body, whether any road vehicle or wing profile, the use of Active Flow Control (AFC) appears to be an efficient technology. Among the different (AFC) methodologies the use of periodic forcing is ment to have better efficiency since it requires less energy to activate the shear layer, the reason behind this efficiency lies on the fact that periodic forcing interacts with the shear layer natural instabilites. In the present paper, one of the devices widely emloyed to generate pulsating flow, is carefully studied via 3D-CFD and using OpenFOAM. Initially the base flow is being determined and compared with previous experimental results, in a second step several internal dimensions of the fluidic actuator are being modified to characterize the output frequency and amplitude variations, among the conclusions obtained it is found that a given fluidic actuator is capable of generating several output frequencies and amplitudes when modifying some internal dimensions while maintaining a constant incoming flow Reynolds number.Influence of data resolution in nonlinear loads model for harmonics prediction
http://hdl.handle.net/2117/106333
Influence of data resolution in nonlinear loads model for harmonics prediction
Balcells Sendra, Josep; Lamich Arocas, Manuel; Griful Ponsati, Eulàlia; Corbalán Fuertes, Montserrat
This paper describes the influence of data resolution in the agreement of models to predict harmonics generated by nonlinear loads (NLL), basically formed by single phase and three phase rectifiers, eventually combined with linear loads. We assume that the network supplying the NLL has significant impedances and that it is disturbed by other parallel, random and unknown neighbor loads, sharing part of the supply system. The aim of building NLL models is to make predictions on the amount and flow paths of harmonic currents generated by such NLL in case of using parallel filters. In this paper, the models are obtained from sets of (V,I) data taken at a certain point, called measuring point (MP) and are valid to predict the NLL behavior when random known or unknown parallel loads are connected upstream of this point. The technique used to obtain the models studied here is based on Multivariate Multiple Outputs Regression (MMOR) and will not be described in detail in this paper. This method allows obtaining a set of equations giving the current harmonics as a function of voltage harmonics observed at the measuring point (MP). The accordance between model and the experimental results is very dependent on the resolution and accuracy of V and I measurements at the MP and is the core matter of this paper.
2017-07-11T07:59:53ZBalcells Sendra, JosepLamich Arocas, ManuelGriful Ponsati, EulàliaCorbalán Fuertes, MontserratThis paper describes the influence of data resolution in the agreement of models to predict harmonics generated by nonlinear loads (NLL), basically formed by single phase and three phase rectifiers, eventually combined with linear loads. We assume that the network supplying the NLL has significant impedances and that it is disturbed by other parallel, random and unknown neighbor loads, sharing part of the supply system. The aim of building NLL models is to make predictions on the amount and flow paths of harmonic currents generated by such NLL in case of using parallel filters. In this paper, the models are obtained from sets of (V,I) data taken at a certain point, called measuring point (MP) and are valid to predict the NLL behavior when random known or unknown parallel loads are connected upstream of this point. The technique used to obtain the models studied here is based on Multivariate Multiple Outputs Regression (MMOR) and will not be described in detail in this paper. This method allows obtaining a set of equations giving the current harmonics as a function of voltage harmonics observed at the measuring point (MP). The accordance between model and the experimental results is very dependent on the resolution and accuracy of V and I measurements at the MP and is the core matter of this paper.A-posteriori error estimation for the finite point method with applications to compressible flow
http://hdl.handle.net/2117/104305
A-posteriori error estimation for the finite point method with applications to compressible flow
Ortega, Enrique; Flores Le Roux, Roberto Maurice; Oñate Ibáñez de Navarra, Eugenio; Idelsohn Barg, Sergio Rodolfo
An a-posteriori error estimate with application to inviscid compressible flow problems is presented. The estimate is a surrogate measure of the discretization error, obtained from an approximation to the truncation terms of the governing equations. This approximation is calculated from the discrete nodal differential residuals using a reconstructed solution field on a modified stencil of points. Both the error estimation methodology and the flow solution scheme are implemented using the Finite Point Method, a meshless technique enabling higher-order approximations and reconstruction procedures on general unstructured discretizations. The performance of the proposed error indicator is studied and applications to adaptive grid refinement are presented.
2017-05-11T08:48:09ZOrtega, EnriqueFlores Le Roux, Roberto MauriceOñate Ibáñez de Navarra, EugenioIdelsohn Barg, Sergio RodolfoAn a-posteriori error estimate with application to inviscid compressible flow problems is presented. The estimate is a surrogate measure of the discretization error, obtained from an approximation to the truncation terms of the governing equations. This approximation is calculated from the discrete nodal differential residuals using a reconstructed solution field on a modified stencil of points. Both the error estimation methodology and the flow solution scheme are implemented using the Finite Point Method, a meshless technique enabling higher-order approximations and reconstruction procedures on general unstructured discretizations. The performance of the proposed error indicator is studied and applications to adaptive grid refinement are presented.In situ particle zeta potential evaluation in electroosmotic flows from time-resolved microPIV measurements
http://hdl.handle.net/2117/103563
In situ particle zeta potential evaluation in electroosmotic flows from time-resolved microPIV measurements
Sureda Anfres, Miquel; Miller, Andrew; Diez, F. J.
A time-resolved microPIV method is presented to measure in an EOF the particles zeta potential in situ during the transient start-up of a microdevice. The method resolves the electrophoretic velocity of fluoro-spheres used as tracer particles in microPIV. This approach exploits the short transient regime of the EOF generated after a potential drop is imposed across a microchannel and before reaching quasisteady state. During the starting of the transient regime, the electrophoretic effect is dominant in the center of the channel and the EOF is negligible. By measuring the velocity of the tracer particles with a microPIV system during that starting period, their electrophoretic velocity is obtained. The technique also resolves the temporal evolution of the EOF with three regions identified. The first region occurs before the electroosmotic effect reaches the center of the channel, the second region extends until the EOF reaches steady state, and thereafter is the third region. The two time constants separating these regions are also obtained and compared to the theory. The zeta potential of 860 nm diameter polystyrene particles is calculated for different solutions including borate buffer, sodium chloride, and deionized water. Results show that the magnitudes of the electrophoretic and electroosmotic velocities are in the range of |300| to |700| µm/s for these measurements. The zeta potential values are compared to the well-established closed cell technique showing improved accuracy. The method also resolves the characteristic response time of the EOF, showing small but important deviations from current analytical predictions. Additionally, the measurements can be performed in situ in microfluidic devices under actual working EOF conditions and without the need for calibrations.
2017-04-20T08:07:22ZSureda Anfres, MiquelMiller, AndrewDiez, F. J.A time-resolved microPIV method is presented to measure in an EOF the particles zeta potential in situ during the transient start-up of a microdevice. The method resolves the electrophoretic velocity of fluoro-spheres used as tracer particles in microPIV. This approach exploits the short transient regime of the EOF generated after a potential drop is imposed across a microchannel and before reaching quasisteady state. During the starting of the transient regime, the electrophoretic effect is dominant in the center of the channel and the EOF is negligible. By measuring the velocity of the tracer particles with a microPIV system during that starting period, their electrophoretic velocity is obtained. The technique also resolves the temporal evolution of the EOF with three regions identified. The first region occurs before the electroosmotic effect reaches the center of the channel, the second region extends until the EOF reaches steady state, and thereafter is the third region. The two time constants separating these regions are also obtained and compared to the theory. The zeta potential of 860 nm diameter polystyrene particles is calculated for different solutions including borate buffer, sodium chloride, and deionized water. Results show that the magnitudes of the electrophoretic and electroosmotic velocities are in the range of |300| to |700| µm/s for these measurements. The zeta potential values are compared to the well-established closed cell technique showing improved accuracy. The method also resolves the characteristic response time of the EOF, showing small but important deviations from current analytical predictions. Additionally, the measurements can be performed in situ in microfluidic devices under actual working EOF conditions and without the need for calibrations.Research on fluidic amplifiers dimensional modifications via computer simulation (CFD)
http://hdl.handle.net/2117/103413
Research on fluidic amplifiers dimensional modifications via computer simulation (CFD)
Baghaei, Masoud; Bergadà Granyó, Josep Maria; Campo Sud, David del; Campo Gatell, Vanessa del
When studying active flow control applications, it is already stated that activating the boundary layer via using periodic flow produces better performance than when employing steady blowing or sucking. This is why studying the performance characteristics of devices like fluidic oscillators and zero net mass flow actuators is particularly interesting. In the present paper a particular configuration of fluidic oscillator is carefully analyzed, initially its dynamic performance is compared with experimental results undertaken by previous researchers, then the dimensional internal characteristics are modified in order to obtain how is the dynamic behavior being affected, in a third stage the evaluation of how fluidic oscillators scale is affecting its dynamic performance is also presented. Based on the results obtained it can be concluded that a given actuator working at a given Reynolds number, is capable of producing different frequencies and amplitudes when modifying some dimensional parameters.
2017-04-06T10:39:56ZBaghaei, MasoudBergadà Granyó, Josep MariaCampo Sud, David delCampo Gatell, Vanessa delWhen studying active flow control applications, it is already stated that activating the boundary layer via using periodic flow produces better performance than when employing steady blowing or sucking. This is why studying the performance characteristics of devices like fluidic oscillators and zero net mass flow actuators is particularly interesting. In the present paper a particular configuration of fluidic oscillator is carefully analyzed, initially its dynamic performance is compared with experimental results undertaken by previous researchers, then the dimensional internal characteristics are modified in order to obtain how is the dynamic behavior being affected, in a third stage the evaluation of how fluidic oscillators scale is affecting its dynamic performance is also presented. Based on the results obtained it can be concluded that a given actuator working at a given Reynolds number, is capable of producing different frequencies and amplitudes when modifying some dimensional parameters.Successes and challenges of a collaborative-PBL program in engineering degrees
http://hdl.handle.net/2117/97771
Successes and challenges of a collaborative-PBL program in engineering degrees
González Vila, Joaquin; Font Andreu, Jorge; Salán Ballesteros, Maria Núria; García-Almiñana, Daniel; Ortiz Marzo, José Antonio; Mudarra López, Miguel; Griful Ponsati, Eulàlia
This paper presents an extracurricular program called INSPIRE3 that has been implemented by the ETSEIAT (Escola Tècnica
Superior d’Enginyeries Industrial i Aeronàutica de Terrassa), a center belonging to the UPC-BarcelonaTech (Universitat
Politècnica de Catalunya). This program is mainly aimed at facilitating cross-curricular skills and developing abilities among
students through collaborative-project based learning. The projection of an attractive external image of engineering degrees
offered by ETSEIAT in order to increase the enrollment in such degrees is a secondary goal of this program. Under INSPIRE3,
several real, challenging and multidisciplinary engineering projects are currently under development. The main feature of this
program is that the subjects of the projects are proposed by the students themselves. In this paper, INSPIRE3 motivation,
program management and implementation process are described and a short description of projects under development is also
given.
Comunicació presentada a
2016-12-05T13:03:17ZGonzález Vila, JoaquinFont Andreu, JorgeSalán Ballesteros, Maria NúriaGarcía-Almiñana, DanielOrtiz Marzo, José AntonioMudarra López, MiguelGriful Ponsati, EulàliaThis paper presents an extracurricular program called INSPIRE3 that has been implemented by the ETSEIAT (Escola Tècnica
Superior d’Enginyeries Industrial i Aeronàutica de Terrassa), a center belonging to the UPC-BarcelonaTech (Universitat
Politècnica de Catalunya). This program is mainly aimed at facilitating cross-curricular skills and developing abilities among
students through collaborative-project based learning. The projection of an attractive external image of engineering degrees
offered by ETSEIAT in order to increase the enrollment in such degrees is a secondary goal of this program. Under INSPIRE3,
several real, challenging and multidisciplinary engineering projects are currently under development. The main feature of this
program is that the subjects of the projects are proposed by the students themselves. In this paper, INSPIRE3 motivation,
program management and implementation process are described and a short description of projects under development is also
given.Ram-air parachute simulation with panel methods and staggered coupling
http://hdl.handle.net/2117/91426
Ram-air parachute simulation with panel methods and staggered coupling
Ortega, Enrique; Flores Le Roux, Roberto Maurice; Pons Prats, Jordi
2016-11-03T13:43:42ZOrtega, EnriqueFlores Le Roux, Roberto MauricePons Prats, JordiReliability versus mass optimization of CO2 extraction technologies for long duration missions
http://hdl.handle.net/2117/89135
Reliability versus mass optimization of CO2 extraction technologies for long duration missions
Detrell Domingo, Gisela; Griful Ponsati, Eulàlia; Messerschmid, Ernst
The aim of this paper is to optimize reliability and mass of three CO2 extraction technologies/components: the 4-Bed Molecular Sieve, the Electrochemical Depolarized Concentrator and the Solid Amine Water Desorption. The first one is currently used in the International Space Station and the last two are being developed, and could be used for future long duration missions. This work is part of a complex study of the Environmental Control and Life Support System (ECLSS) reliability. The result of this paper is a methodology to analyze the reliability and mass at a component level, which is used in this paper for the CO2 extraction technologies, but that can be applied to the ECLSS technologies that perform other tasks, such as oxygen generation or water recycling, which will be a required input for the analysis of an entire ECLSS. The key parameter to evaluate any system to be used in space is mass, as it is directly related to the launch cost. Moreover, for long duration missions, reliability will play an even more important role, as no resupply or rescue mission is taken into consideration. Each technology is studied as a reparable system, where the number of spare parts to be taken for a specific mission will need to be selected, to maximize the reliability and minimize the mass of the system. The problem faced is a Multi-Objective Optimization Problem (MOOP), which does not have a single solution. Thus, optimum solutions of MOOP, the ones that cannot be improved in one of the two objectives, without degrading the other one, are found for each selected technology. The solutions of the MOOP for the three technologies are analyzed and compared, considering other parameters such as the type of mission, the maturity of the technology and potential interactions/synergies with other technologies of the ECLSS.
2016-07-25T10:43:03ZDetrell Domingo, GiselaGriful Ponsati, EulàliaMesserschmid, ErnstThe aim of this paper is to optimize reliability and mass of three CO2 extraction technologies/components: the 4-Bed Molecular Sieve, the Electrochemical Depolarized Concentrator and the Solid Amine Water Desorption. The first one is currently used in the International Space Station and the last two are being developed, and could be used for future long duration missions. This work is part of a complex study of the Environmental Control and Life Support System (ECLSS) reliability. The result of this paper is a methodology to analyze the reliability and mass at a component level, which is used in this paper for the CO2 extraction technologies, but that can be applied to the ECLSS technologies that perform other tasks, such as oxygen generation or water recycling, which will be a required input for the analysis of an entire ECLSS. The key parameter to evaluate any system to be used in space is mass, as it is directly related to the launch cost. Moreover, for long duration missions, reliability will play an even more important role, as no resupply or rescue mission is taken into consideration. Each technology is studied as a reparable system, where the number of spare parts to be taken for a specific mission will need to be selected, to maximize the reliability and minimize the mass of the system. The problem faced is a Multi-Objective Optimization Problem (MOOP), which does not have a single solution. Thus, optimum solutions of MOOP, the ones that cannot be improved in one of the two objectives, without degrading the other one, are found for each selected technology. The solutions of the MOOP for the three technologies are analyzed and compared, considering other parameters such as the type of mission, the maturity of the technology and potential interactions/synergies with other technologies of the ECLSS.Review of Lambert's problem
http://hdl.handle.net/2117/86429
Review of Lambert's problem
Torre Sangrà, David de la; Fantino, Elena
Lambert’s problem is the orbital boundary-value problem constrained by two points and elapsed time. It is one of the most extensively studied problems in celestial mechanics and astrodynamics, and, as such, it has always attracted the interest of mathematicians and engineers. Its solution lies at the base of algorithms for, e.g., orbit determination, orbit design (mission planning), space rendezvous and interception, space debris correlation, missile and spacecraft targeting. There is abundance of literature discussing various approaches developed over the years to solve Lambert’s problem. We have collected more than 70 papers and, of course, the issue is treated in most astrodynamics and celestial mechanics textbooks. From our analysis of the documents, we have been able to identify five or six main solution methods, each associated to a number of revisions and variations, and many, so to say, secondary research lines with little or no posterior development. We have ascertained plenty of literature with proposed solutions, in many cases supplemented by performance comparisons with other methods. We have reviewed and organized the existing bibliography on Lambert’s problem and we have performed a quantitative comparison among the existing methods for its solution. The analysis is based on the following issues: choice of the free parameter, number of iterations,generality of the mathematical formulation, limits of applicability (degeneracies, domain of the parameter, special cases and peculiarities), accuracy, and suitability to automatic execution. Eventually we have tested the performance of each code. The solvers that incorporate the best qualities are Bate’s algorithm via universal variables with Newton-Raphson and Izzo’s Householder algorithm. The former is the fastest, the latter exhibits the best ratio between speed, robustness and accuracy.
2016-04-29T13:51:49ZTorre Sangrà, David de laFantino, ElenaLambert’s problem is the orbital boundary-value problem constrained by two points and elapsed time. It is one of the most extensively studied problems in celestial mechanics and astrodynamics, and, as such, it has always attracted the interest of mathematicians and engineers. Its solution lies at the base of algorithms for, e.g., orbit determination, orbit design (mission planning), space rendezvous and interception, space debris correlation, missile and spacecraft targeting. There is abundance of literature discussing various approaches developed over the years to solve Lambert’s problem. We have collected more than 70 papers and, of course, the issue is treated in most astrodynamics and celestial mechanics textbooks. From our analysis of the documents, we have been able to identify five or six main solution methods, each associated to a number of revisions and variations, and many, so to say, secondary research lines with little or no posterior development. We have ascertained plenty of literature with proposed solutions, in many cases supplemented by performance comparisons with other methods. We have reviewed and organized the existing bibliography on Lambert’s problem and we have performed a quantitative comparison among the existing methods for its solution. The analysis is based on the following issues: choice of the free parameter, number of iterations,generality of the mathematical formulation, limits of applicability (degeneracies, domain of the parameter, special cases and peculiarities), accuracy, and suitability to automatic execution. Eventually we have tested the performance of each code. The solvers that incorporate the best qualities are Bate’s algorithm via universal variables with Newton-Raphson and Izzo’s Householder algorithm. The former is the fastest, the latter exhibits the best ratio between speed, robustness and accuracy.