Ponències/Comunicacions de congressos
http://hdl.handle.net/2117/3483
2018-01-18T16:16:34ZFluidic 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.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.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.Analysis of perturbations and station-keeping requirements in highly-inclined geosynchronous orbits
http://hdl.handle.net/2117/86428
Analysis of perturbations and station-keeping requirements in highly-inclined geosynchronous orbits
Fantino, Elena; Flores Le Roux, Roberto Maurice; Di Salvo, Alessio; Di Carlo, Marilena
There is a demand for communications services at high latitudes that is not well served by conventional geostationary satellites. Alternatives using low-altitude orbits require too large constellations. Other options are the Molniya and Tundra families (critically-inclined, eccentric orbits with the apogee at high latitudes). In this work we have considered derivatives of the Tundra type with different inclinations and eccentricities. By means of a high-precision model of the terrestrial gravity field and the most relevant environmental perturbations, we have studied the evolution of these orbits during a period of two years. The effects of the different perturbations on the constellation ground track (which is more important for coverage than the orbital elements themselves) have been identified. We show that, in order to maintain the ground track unchanged, the most important parameters are the orbital period and the argument of the perigee. Very subtle changes in the orbital period (due mainly to lunar perturbations) cause a large east-west drift of the ground trace which dwarfs the displacement due to the regression of the ascending node. From these findings, a station-keeping strategy that minimizes propellant consumption has then been devised. Our results offer interesting guidelines for the design and operation of satellite constellations using these orbits.
2016-04-29T13:21:01ZFantino, ElenaFlores Le Roux, Roberto MauriceDi Salvo, AlessioDi Carlo, MarilenaThere is a demand for communications services at high latitudes that is not well served by conventional geostationary satellites. Alternatives using low-altitude orbits require too large constellations. Other options are the Molniya and Tundra families (critically-inclined, eccentric orbits with the apogee at high latitudes). In this work we have considered derivatives of the Tundra type with different inclinations and eccentricities. By means of a high-precision model of the terrestrial gravity field and the most relevant environmental perturbations, we have studied the evolution of these orbits during a period of two years. The effects of the different perturbations on the constellation ground track (which is more important for coverage than the orbital elements themselves) have been identified. We show that, in order to maintain the ground track unchanged, the most important parameters are the orbital period and the argument of the perigee. Very subtle changes in the orbital period (due mainly to lunar perturbations) cause a large east-west drift of the ground trace which dwarfs the displacement due to the regression of the ascending node. From these findings, a station-keeping strategy that minimizes propellant consumption has then been devised. Our results offer interesting guidelines for the design and operation of satellite constellations using these orbits.Modelling harmonics drawn by nonlinear loads
http://hdl.handle.net/2117/76228
Modelling harmonics drawn by nonlinear loads
Lamich Arocas, Manuel; Balcells Sendra, Josep; Mon González, Juan; Corbalán Fuertes, Montserrat; Griful Ponsati, Eulàlia
This paper is devoted to obtain a model of
nonlinear loads (NLL) connected to LV electric networks, in
order to predict the consequences of including parallel active or
passive filters. The model is based on Neural Networks (NNs) and
its purpose is the prediction of harmonic currents generated by a
certain load when supplied by a network with significant series
impedance, disturbed by other random and unknown neighbour
loads. The NNs have been trained by using data obtained from
several circuit simulations of a network supplying several
unknown neighbour loads beside the load of interest, consisting
of a set of rectifiers. The model is validated using the same
network structure, with different neighbour loads and different
load conditions.
2015-07-20T11:37:01ZLamich Arocas, ManuelBalcells Sendra, JosepMon González, JuanCorbalán Fuertes, MontserratGriful Ponsati, EulàliaThis paper is devoted to obtain a model of
nonlinear loads (NLL) connected to LV electric networks, in
order to predict the consequences of including parallel active or
passive filters. The model is based on Neural Networks (NNs) and
its purpose is the prediction of harmonic currents generated by a
certain load when supplied by a network with significant series
impedance, disturbed by other random and unknown neighbour
loads. The NNs have been trained by using data obtained from
several circuit simulations of a network supplying several
unknown neighbour loads beside the load of interest, consisting
of a set of rectifiers. The model is validated using the same
network structure, with different neighbour loads and different
load conditions.Preliminary study on fluidic actuators. Design modifications
http://hdl.handle.net/2117/28310
Preliminary study on fluidic actuators. Design modifications
Campo Sud, David del; Bergadà Granyó, Josep Maria; Campo Gatell, Vanessa del
As fluidic actuators have the advantage of lacking moving parts, their use in real applications brings high reliability. This is why, once having overcome their drawbacks, which means being able to provide the appropriate momentum and frequency, they could extensively be used in a wide range of applications. The present paper will present a CFD evaluation of the flow inside a fluidic oscillator. Initially a standard fluidic actuator will be simulated and the results compared with existing experimental data. In a second step, several geometric parameters will be modified; the actuator performance under these new conditions is reported. The paper aims to be an aid for future innovative oscillator designs.
2015-06-15T15:31:45ZCampo Sud, David delBergadà Granyó, Josep MariaCampo Gatell, Vanessa delAs fluidic actuators have the advantage of lacking moving parts, their use in real applications brings high reliability. This is why, once having overcome their drawbacks, which means being able to provide the appropriate momentum and frequency, they could extensively be used in a wide range of applications. The present paper will present a CFD evaluation of the flow inside a fluidic oscillator. Initially a standard fluidic actuator will be simulated and the results compared with existing experimental data. In a second step, several geometric parameters will be modified; the actuator performance under these new conditions is reported. The paper aims to be an aid for future innovative oscillator designs.A simulation tool for parachute/payload systems
http://hdl.handle.net/2117/26732
A simulation tool for parachute/payload systems
Flores Le Roux, Roberto Maurice; Ortega, Enrique; Vallés Fluvià, J.; Oñate Ibáñez de Navarra, Eugenio
The design and evaluation of parachute-payload systems is a technology field in which numerical analysis tools can make very important contributions. This work describes a new development from CIMNE in this area, a coupled fluid-structural solver for unsteady
simulations of ram-air type parachutes. For an efficient solution of the aerodynamic problem, an unsteady panel method has been chosen exploiting the fact that large areas of separated
flow are not expected under nominal flight conditions of ram-air parachutes. A dynamic explicit finite element solver is used for the structure. This approach yields a robust solution
even when highly non-linear effects due to large displacements and material response are present. An added benefit of the proposed aerodynamic and structural techniques is that they
can be easily parallelized for increased performance in multi-core and multi-CPU architectures. The main features of the computational tools are described and several numerical examples are provided to illustrate the performance and capabilities of the
technique.
2015-03-16T14:39:52ZFlores Le Roux, Roberto MauriceOrtega, EnriqueVallés Fluvià, J.Oñate Ibáñez de Navarra, EugenioThe design and evaluation of parachute-payload systems is a technology field in which numerical analysis tools can make very important contributions. This work describes a new development from CIMNE in this area, a coupled fluid-structural solver for unsteady
simulations of ram-air type parachutes. For an efficient solution of the aerodynamic problem, an unsteady panel method has been chosen exploiting the fact that large areas of separated
flow are not expected under nominal flight conditions of ram-air parachutes. A dynamic explicit finite element solver is used for the structure. This approach yields a robust solution
even when highly non-linear effects due to large displacements and material response are present. An added benefit of the proposed aerodynamic and structural techniques is that they
can be easily parallelized for increased performance in multi-core and multi-CPU architectures. The main features of the computational tools are described and several numerical examples are provided to illustrate the performance and capabilities of the
technique.Multidisciplinary study of tutoring using virtual characters and second life
http://hdl.handle.net/2117/18862
Multidisciplinary study of tutoring using virtual characters and second life
Amante García, Beatriz; Campo Sud, David del; Martínez Martínez, María del Rosario
In this article we present the planning and methodology followed in order to apply virtual tutoring sessions in different subjects and universities. The Second Life environment, together with the Voki speaking avatars will be employed. It is a multidisciplinary study that includes personal and collective tutoring sessions, answering key questions through animated avatars, virtual labs, and posters exhibition for peer-evaluation. From a survey run among the students it is concluded that most of them are willing to learn and try this kind of tutoring sessions, but at the same time some feel skeptical about its utility
2013-04-18T10:23:24ZAmante García, BeatrizCampo Sud, David delMartínez Martínez, María del RosarioIn this article we present the planning and methodology followed in order to apply virtual tutoring sessions in different subjects and universities. The Second Life environment, together with the Voki speaking avatars will be employed. It is a multidisciplinary study that includes personal and collective tutoring sessions, answering key questions through animated avatars, virtual labs, and posters exhibition for peer-evaluation. From a survey run among the students it is concluded that most of them are willing to learn and try this kind of tutoring sessions, but at the same time some feel skeptical about its utilityA numerical simulation of fluid-structure interaction for flow through valves of a hermetic compressor with immersed boundary method
http://hdl.handle.net/2117/18358
A numerical simulation of fluid-structure interaction for flow through valves of a hermetic compressor with immersed boundary method
Mushyam, Aditya; Bergadà Granyó, Josep Maria
2013-03-15T16:53:47ZMushyam, AdityaBergadà Granyó, Josep Maria