Dissertations / Theses on the topic 'Performances aérodynamiques'
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Dumont, Antoine. "Calculs de gradients pour l'optimisation des performances aérodynamiques d'un rotor d'hélicoptère en vol stationnaire." Poitiers, 2010. http://www.theses.fr/2010POIT2327.
Full textThis thesis work is dedicated to the development of efficient sensitivity analysis methods in the context of aerodynamic shape optimization considering the application of an isolated helicopter rotor in hover, for which the flow can be considered as steady in a rotating frame. Sensitivity quantities represent in fact an important information to any gradient based method used to solve local optimisation problems. For the flow analysis, the governing equations (RANS) are discretized using a finite volume method and are solved with the ONERA CFD code elsA. The two methods implemented in elsA for the specific formulation in a rotating frame are the discrete direct differentiation method and the discrete adjoint method which presents the interesting characteristic of being quasi-independent in terms of computational cost with respect to the number of shape parameters of the problem. They both rely on the differentiation of the flow solver and of the cost function which, in that context, is the aerodynamic efficiency of a hovering rotor, named the figure of merit (FM). Some single-objective shape optimizations have been done with the goal of improving the maximum of figure of merit of a rotor. They show the capability of the optimization process to converge to blade planform that improve significantly the figure of merit over a large range of thrust and that give an increase in load capacity of the rotor. This work could be used to perform local optimization of any rotary wing or fan in purely axial flight condition
Schneider, Alexandra Patrizia. "Aerodynamic and aeroelastic investigation of a composite fan for ultra-high-bypass-ratio aircraft engines." Electronic Thesis or Diss., Ecully, Ecole centrale de Lyon, 2024. http://www.theses.fr/2024ECDL0018.
Full textModern low-speed Ultra-High Bypass Ratio (UHBR) fans operate predominantly on the flat part of the compression characteristic, have shorter intake lengths, and employ flexible, lightweight, composite blades. These changes promote the evolution of different types of instabilities with multi-physical interactions such as convective non-synchronous vibration (NSV). To enable further technological ad-vancements, experimental benchmark data on representative geometries required. Within this con-text, the European project CATANA was initiated at Ecole Centrale de Lyon. The open-test-case fan stage ECL5 was designed, following industrial guidelines, and tested experimentally on the facility ECL-B3. This thesis presents the experimental results of the CATANA project. The experimental investiga-tion of the ECL5 reference configuration shows that all design goals have been reached. The machine is operational in a wide range and aerodynamic performance at design condition is exactly coincident with the numerical prediction. In contrast, instability mechanisms are more complex than predicted by the employed numerical methods. Through application of synchronized multi-physical instrumenta-tion, the involved complex fluid-structure interaction is resolved. The analysis of the influence of in-flow conditions and geometrical and structural system symmetry allows to identify the sensitivity of aerodynamic and structural characteristics and the behavior close to the stability limit. The investiga-tion of a second rotor configuration featuring structural mistuning highlights the importance of geo-metrical blade-to-blade variations. They cause an asymmetry of the aerodynamic field at the blade tip and suppress coherently propagating aerodynamic disturbances resulting in a delayed onset of NSV. The results presented in this thesis provide a comprehensive multi-physical characterization of the ECL5 fan stage and serve as a benchmark data set for the validation of numerical simula-tions
Belleil, Cédric. "Calcul direct des performances aérodynamique et acoustique d'un silencieux industriel par modélisation CFD, et optimisation aérodynamique." Mémoire, École de technologie supérieure, 2005. http://espace.etsmtl.ca/338/1/BELLEIL_C%C3%A9dric.pdf.
Full textLv, Peng. "Performance aérodynamique et structurelle du rotor flexible pour micro-drones." Thesis, Toulouse, ISAE, 2014. http://www.theses.fr/2014ESAE0058/document.
Full textThe wind tunnel tests were conducted to explore the performance difference caused by the potential twist deformation between baseline blades and flexible blades. The balance was built in SaBre wind tunnel for measuring the thrust and torque of blades. The BEMT predictions of blades with varied twist were also performed in hover and forward flight, respectively. In hover,flexible blades cannot help in improving the FM at light disk loading since the twist generated on flexible blades is probably beyond the ideal hover twist. In forward flight, the propulsive efficiency η of flexible blades is mostly higher than baseline blades due to the beneficial twist generated in rotation. A Particle Image Velocimetry (PIV) approach of loads determination was developed based on control volume method to obtain thrust and torque of small-scale proprotor,especially for off-optimum conditions. The pressure Poisson equation was implemented for the pressure estimation based on the PIV velocity data. The axial velocity of flexible blades is found to be lower than baseline blades on the same station at downstream. This corresponds to the lower inflow ratio distribution along flexible blade, which results from the negative twist deformation. For both baseline blades and flexible blades, the thrust differences between PIV test 2 and balance are larger when compared to the differences between PIV test 1 based on nearfield and balance. The Laser Displacement Sensor (LDS) technique was employed for measuring the stationary deformation of rotating flexible blades. By obtaining the LDS point cloud, the bending and torsion of the rotating blade were identified using the multiple regressions
Chabroux, Vincent. "Approche aérodynamique et biomécanique de l'amélioration des performances de cyclistes en course contre la montre." Thesis, Aix-Marseille 2, 2010. http://www.theses.fr/2010AIX22037/document.
Full textThe aim of this study is to determine the aerodynamic and biomechanical factors influencing cyclists performance during Time Trial stage (TT). The aerodynamic drag force represents over 90% of the power generated by the cyclist during TT stage. The aerodynamic optimization of the cyclist posture and equipment is thus a main objective. Experimentations were carried out in the wind tunnel S1L of the Institute of Movement sciences, in order to measure the aerodynamic drag force of cyclist according to different configurations. Measurements of the projected frontal led to a modeling of the cyclist frontal area value according to postural parameters. Aerodynamic performance of several TT helmets was characterized by measurement of the velocity fields in their downstream wake using a PIV-3C method (Particle Image Velocimetry 3 components). Results of this study have identified an optimized geometry of TT helmets. The aim of the biomechanical approach is to study the influence of the aerodynamic postural parameters studied on the performance of the cyclists. An inverse dynamics models is used to determine the torques and forces at each leg joint according to the saddle position and the power developed. The inverse dynamic calculation requires measurement of the pedal forces and the cycling motion. The motion analysis system VICON was used and two special 6 components sensors were design for this application. Results of this study have identified postural parameters increasing the performance. The synthesis of the factors influencing aerodynamic and biomechanical performances achieves a performance improvement of about 3%
Ortolan, Aurélie. "Etude aérodynamique de ventilateurs axiaux réversibles à performance duale compresseur/turbine élevée." Thesis, Toulouse, ISAE, 2017. http://www.theses.fr/2017ESAE0019/document.
Full textIn the more electric aircrafts context, the in-flight windmilling operation of conventional onboard axial fans is regarded as a functioning mode that enables energy recovery. Poor turbine efficiencies of classical geometries, due to massive separations, require to design a reversible machine. The latter allows a dual compressor/turbine functioning with high performances in both modes to capitalize the equipment throughout the mission. In this study, the relevance of psi-phi formalism to multi-quadrant approach is underlined. The flow analysis from compressor to load-controlled windmill enables to highlight generic properties of windmilling flows as well as dual machines specificities. The flow mechanisms and geometrical parameters impacting the performances along the operating line are also identified. Finally, an optimized dual machine design is proposed
Toubin, Hélène. "Prediction and phenomenological breakdown of drag for unsteady flows." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066576/document.
Full textAccurate drag prediction is now of a major issue for aircraft designers. Its phenomenological sources need to be identified and quantified for an efficient design process. Far-field methods, which allow such phenomenological drag breakdown, are however restricted to steady flows. This study consists in developing a far-field drag prediction method aiming at a phenomenological breakdown of drag for unsteady flows. The first step has consisted in generalizing the steady formulation of Van der Vooren to unsteady flows, starting from a new rigorous proof. Axes for the improvement of the robustness and physical background have then been explored. Acoustic contributions have in particular been highlighted and quantified. The resulting five-components formulation has then been applied to simple cases, in order to validate as best as possible the phenomenological breakdown. The behavior of the drag components has proved to be consistent with the physics of the flow. Finally, the method has been applied to complex cases in order to demonstrate its capabilities: a 3-D case and a flow simulated by the ZDES method. In the future, it would be interesting to further improve the definition of the induced drag component, for example by using velocity-based formulations. As far as the application cases are concerned, the performance evaluation of a Counter-Rotating-Open-Rotor would strongly benefit from such a method. Unsteady optimization of one of the drag component could also be contemplated. Finally, applications in aeroelasticity or flapping flight would be an interesting perspective
Laverne, Thomas. "Aérodynamique des éoliennes à axe horizontal : effets de la turbulence de l'écoulement amont et de la rotation sur le comportement aérodynamique des profils constitutifs : conséquences sur le fonctionnement et les performances." Orléans, 2003. http://www.theses.fr/2003ORLE2053.
Full textLauriau, Pierre-Thomas. "Caractérisation de la performance aérodynamique d'un étage de turbine radiale à géométrie variable, en fonctionnement hors-adaptation." Thesis, Toulouse, ISAE, 2019. http://www.theses.fr/2019ESAE0004/document.
Full textThe technological mutation of transport in general and aeronautics in particular, engaged to the European level, leads to an evolution of more economical and fuel-efficient aircrafts. It strongly impacts the environmental control systems by a partial electrification which does not need an air bleeding on the engine anymore. Then it is necessary to insure a large output range through the turbine, element of the turbomachine which forms the heart of the air conditioning « pack », while providing the maximum amount of possible power on the whole range. The classical turbine stage cannot insure the specified output range. Then it is replaced by a variable geometry radial inflow turbine. This turbine stage has to function from the maintenance phase on the ground (weak output, strong expansion ratio) to the en route phase (strong output, weak expansion ratio). It also has to guarantee its role during the others phases of flight and in case of multiple failures power. So the problematic is to design a turbine such that its geometry varies in operation and adapt itself to the changing operating with the best possible efficiency on the widest possible range. Thus it is primordial to understand beforehand the complexity of flows for this kind of geometry, and how the variable geometry device affects the flow topology in the turbine stage. In particular, the presence of clearances in the static parts of the stage creates a vortex perturbation upstream from the rotor. The impact of this perturbation on the main flow, its interaction with secondary flows, must be detailed. The influence of the perturbation localisation, its intensity, must be analysed, in the complex variable geometry context. The understanding of phenomenon involved and responsible for the downgrade of performance in the turbine stage, will allow defining a specific strategy of design. The improvement of performance for the turbine will enable to restrict the required power on the electrical engine for limiting the on board weight, and then the fuel consumption. The selected methodology to broach this problematic, is divided into four parts. Firstly, a bibliographic part in order to appropriate physics phenomenon related to the flow in a variable geometry turbine will be conducted, together with a state of art about the different existing technological solutions. Secondly, some numerical simulations will be set to propose a methodology of robust calculations for performance prediction and, to discriminate different design options. The third step consists in an experimental phase representing the main work of the thesis. It will consist in the definition of a specific module instrumented for tests representative of the turbine on aircraft functioning. It will provide a database for analysing the flow and validating the numerical simulations, and to quantify the effects of integration. These numerical and experimental studies will be led jointly, such that the general analysis takes advantage of complementarity of both approaches. The last step of this study aims at conditioning the results achieved and the know-how for industrial application
Noubel, Hugo. "Etude expérimentale du comportement aérodynamique et optimisation des performances des planeurs hypersoniques dans des écoulements supersoniques et hypersoniques raréfiés." Electronic Thesis or Diss., Orléans, 2024. http://www.theses.fr/2024ORLE1001.
Full textThe main objective of this thesis work is to experimentally characterize the impact of viscous effects on the aerodynamic performance of hypersonic gliders. The study includes six low-pressure flows (ranging from 0.068 Pa to 71.11 Pa) from the MARHy wind tunnel, four supersonic flows (Mach 2 and Mach 4), and two hypersonic flows (Mach 20). A total of 6 models were tested, aiming to study geometries with different degrees of optimization and to understand the impact of viscous effects one ach of them. Various diagnostics were used to carry out this study : Firstly, an aerodynamic balance was developed to measure the drag and lift forces of the different configurations. Next, shock waves were visualized using glow discharge imaging. Finally, a parietal pressure study was carried out on two hypersonic gliders. This thesis work establishes a broad experimental database on hypersonic gliders in the rarefied regime. Force studies have enabled us to quantify the evolution of glide ratio during atmospheric re-entry as a function of the degree of rarefaction (Tsien parameter). As far as angles of attack are concerned, formulations taking viscous effects into account have been established and can be used in the optimization of high-altitude waveriders. A hypersonic glider incorporating these data has been tested and shows promise at high altitude. Throughout this thesis, results have highlighted the impact of viscous effects on the aerodynamic performance of hypersonic gliders
Villeneuve, Thierry. "Improving the performance of H-Darrieus vertical-axis turbines for their use in isolation and within turbine farms." Doctoral thesis, Université Laval, 2021. http://hdl.handle.net/20.500.11794/69812.
Full textVertical-axis turbines have gained increasing attention in the wind and hydrokinetic energy sectors in recent years. This type of turbine has several interesting advantages over the well-established horizontal-axis wind turbine concept and recent works have suggested that vertical-axis turbines could be favorable for applications in turbine farms. However, this technology is relatively young and more research and development is needed to fully assess their potential in turbine farms. Indeed, it is crucial to better characterize the performance of vertical-axis turbines, find ways to improve their aerodynamic efficiency and understand the different physical mechanisms affecting their wake recovery in order to draw informed conclusions about their eventual use in wind farms and hydrokinetic turbine farms. In this context, the present thesis aims at studying the impact of two design considerations on the efficiency and on the wake recovery of vertical-axis turbines: the use of detached end-plates and the effect of the blade support structures.Firstly, the effect of detached end-plates on the performance and on the wake recovery of a vertical-axis turbine is investigated. A detached end-plate consists of a thin stationary plate that is located very close to the tips of the turbine blades, but not in contact with them. Using numerical simulations (CFD), two geometries of detached end-plates are simulated on a vertical-axis turbine: a circular geometry and a semi-annular one. The results show that these two geometries of detached end-plates allow to significantly increase the efficiency of the vertical-axis turbine considered. The efficiency enhancement can be explained by the viscous interaction that takes place between the turbine bladesand the detached end-plates. This interaction increases the circulation and the lift near the blade tips,which also increases the power extracted from the flow. Regarding the wake, it is shown that the use of semi-annular detached end-plates leads to a faster velocity recovery downstream of the vertical-axis turbine considered. The viscous interaction between the blades and the semi-annular detached end-plates is favorable to the velocity that is induced in the spanwise direction in the turbine wake, and this velocity induction is beneficial to the wake re-energization. Consequently, the velocity recovery in the wake of the turbine with semi-annular detached end-plates is faster than that in the wake of the reference turbine (without detached end-plates).Secondly, always using numerical simulations, the effect of the design and of the position of the blade support structures (i.e., the struts) is investigated on a vertical-axis turbine. The results show that the struts are less detrimental to the turbine efficiency if they are located at the tips of the turbine blades, rather than at other intermediate positions along the blade span. Moreover, it is shown that the use of rounded blade-strut junction geometries allows to increase the turbine efficiency very significantly. Indeed, the use of rounded blade-strut junctions reduces the kinetic energy of the blade tip vortices, and thus, decreases the induced drag considerably. Therefore, rounded blade-strut junctions help to obtain a flow that is essentially two-dimensional over a significant portion of the turbine blades and they also help to reach very interesting efficiency values. Regarding the wake recovery, the position of the struts along the blade span affects the spatial distribution of the vorticity shed in the turbine wake.The results show that struts located at the blade tips are slightly detrimental to the wake recovery incomparison with struts located at other intermediate positions along the blade span. However, because of the significant increase in efficiency, the use of rounded tip struts remains a very interesting option for vertical-axis turbines.
Lê, Van Nha Phuong. "Influence des propriétés physicochimiques du principe actif et du transporteur sur la performance aérodynamique des mélanges de poudre pour inhalation." Phd thesis, Université du Droit et de la Santé - Lille II, 2011. http://tel.archives-ouvertes.fr/tel-00647318.
Full textDebraux, Pierre. "Etude des déterminants de la performance en cyclisme: puissance musculaire et aérodynamisme. Application en BMX." Reims, 2010. http://theses.univ-reims.fr/sciences/2010REIMS013.pdf.
Full textThe BMX competitions take place on a specific track of 300-400 m with bumps and turns, and with a downhill start. The displacement velocity reached by the riders may be greater than 70 kmh-1 a few seconds after the start. Few scientific studies focused to the parameters related to the performance in BMX. Nevertheless, a study showed that the starting phase was capital and that the maximum muscle power was a major contributor to performance during this phase. The aim of this thesis is to study the determinants of performance in this sport in focusing on two main parameters: the muscular power output of the lower limbs and a variable of aerodynamics, the projected frontal area. Firstly, the study of the muscular power output in lower body during sprints on a cycle ergometer and a ½ Squat among road cyclists and BMX riders showed that the muscle cross-sectional area and maximal muscle strength were indicators of performance for all-out sprints (~ 6-30s). A comparison of muscular inertial profiles has shown that BMX riders produced a maximal power output with relative light loads and it was necessary to increase muscular power output at heavy loads. Secondly, a new field method for measuring the projetcted frontal area in cycling has been tested. This method is reproducible and valid in comparison to the methods of weighing photographs and digitization. This method was used to measure the projected frontal area of BMX riders during 80 m sprints. These sprints allowed to highlight the importance of the maximal power, the projected frontal area and the average pedaling rate on the chronometric performance and the need to find an optimal gear to decrease the difference between the average pedaling rate and the optimal pedaling rate. To optimize the performance in competition among the BMX riders, it seems necessary: i) to follow a resistance training to increase muscle mass and muscle maximal strength of the lower limbs; ii) to adjust the gear ratio depending on the riders; and iii) to optimize the projected frontal area for some phases of the race. Solutions are proposed in this thesis
Couteyen, Carpaye Jean Marie. "Contribution à la parallélisation et au passage à l'échelle du code FLUSEPA." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0073/document.
Full textThere are different kinds of satellites that offer different services like communication, navigationor observation. They are put into orbit through the use of launchers whose design is oneof the main activities of Airbus Defence and Space. Relying on experiments is not easy : windtunnel cannot be used to evaluate every critical situation that a launcher will face during itsmission. Numerical simulation is therefore mandatory for spatial industry.In order to have more reliable simulations, more computational power is needed and supercomputersare used. Those supercomputers become more and more complex and this impliesto adapt existing codes to make them run efficiently. Nowadays, it seems important to rely onabstractions in order to ensure a good portability of performance. Airbus Defence and Spacedeveloped for more than 20 years the FLUSEPA code which is used to compute unsteady phenomenalike take-off blast wave or stage separation. The aerodynamic solver relies on a finitevolume formulation and an explicit temporal adaptive solver. Bodies in relative motion are takeninto account through the use of multiple meshes that are overlapped.This thesis is about the parallelization of the FLUSEPA code. At the start of the thesis,the only parallel version available was in shared memory through OpenMP. A first distributedmemory version was realized and relies on MPI and OpenMP. The performance improvementof this version was evaluated on two industrial test cases. A task-based demonstrator of theaerodynamic solver was also realized over a runtime system
Gallard, François. "Optimisation de forme d’un avion pour sa performance sur une mission." Thesis, Toulouse, INPT, 2014. http://www.theses.fr/2014INPT0031/document.
Full textAn aircraft encounters a wide range of operating conditions during its missions, i.e. flight altitude, Mach number and angle of attack, which consideration at the design phase enhances the system robustness and consequently the overall fleet consumption. Numerical optimization of aerodynamic shapes contributes to aircraft design, and relies on the automation of geometry generation and numerical simulations of the flight physics. Minimization of aerodynamic shapes drag must take into account multiple operating conditions, since optimization at a single operating condition leads to a strong degradation of performance when this operating condition varies. Besides, structural flexibility deforms the wings differently depending on the operating conditions, so has to be simulated during such optimizations. In the present thesis, the mission fuel consumption minimization is formulated as an optimization problem. The focus is made on the choice of operating conditions to be included in the optimization problem, since they have a major impact on the quality of the results, and the computational cost is proportional to their number. A new theoretical framework is proposed, overcoming and giving new insights on problematic situations revealed by state-of-the-art methods for multipoint optimization problem setup. An algorithm called Gradient Span Analysis is proposed to automate the choice of operating conditions. It is based on a reduction of dimension of the vector space spanned by adjoint gradients obtained at the different operating conditions. Programming contributions to the optimization chain enabled the evaluation of the new method on the optimizations of the academic RAE2822 airfoil, and the XRF-1 wing-body configuration, representative of a modern transport aircraft. While the shapes resulting of single-point optimizations present strong degradations of the performance in off-design conditions, adequately formulated multi-Machmulti- lift optimizations present much more interesting performance compromises. It is finally shown that fluid-structure interaction adds new degrees of freedom, and has consequences on multiple flight conditions optimizations, opening the perspective of passive shape adaptation
Pinot, Julien. "Etude de la puissance mécanique comme variable d'amélioration de la performance en cyclisme à travers l'interface homme-machine." Thesis, Besançon, 2014. http://www.theses.fr/2014BESA1007/document.
Full textThis thesis has been completed as part of a CIFRE agreement between the laboratory C3S(EA4660) and the Research and Development (R&D) department of the FDJ professionalcycling team. The various studies that we conducted centred on analysing sport performanceoptimisation in cyclists through a central variable: the mechanical power output (PO)developed during locomotion. There were two main areas of focus: 1) evaluation andmonitoring of physical potential, with the aim of improving the training process, and 2)optimisation of the human–machine interface via analysis of the materials and equipmentused by the FDJ team cyclists
Portier, Eric. "Etude de l'écoulement au travers de diffuseurs équipés de vannes de guidage ; analyse des performances et application au contrôle actif des débits pulsés." Poitiers, 2000. http://www.theses.fr/2000POIT2269.
Full textBouillod, Anthony. "Positions sur le vélo et performance en cyclisme." Thesis, Bourgogne Franche-Comté, 2017. http://www.theses.fr/2017UBFCD032/document.
Full textThe studies conducted during this PhD research showed that optimizing the position of the cyclist on the bicycle is a key factor influencing cycling performance. Our research focused on four main axes: the design and validation of measurement tools, the study of the aerodynamic position, the study of the seated position and the study of the standing position.All the results showed that the performance capacity of cyclists can be improved in aerodynamic position by increasing the ratio between the mechanical power (PO) and the drag area (ACd). Comfort is also a significant factor in time trial (TT) performance as it determines the ability of the cyclist to maintain position over time. Our works show that comfort can be improved via orthopaedic correction in cyclists affected by lower limb length inequality (LLLI) in the TT position, related to a reduction in pelvis movements. The orthopaedic correction also induces an increase in gross efficiency (+5.7%). Thus, this improvement in comfort could increase the PO and/or the amount of time the aerodynamic position can be maintained during a TT. Therefore, cyclists affected by LLLI should compensate LLLI with individualised foot orthotics to improve their TT performance. In a preliminary study, we also showed that there is a relationship between head movements and ACd. Therefore, cyclists should minimise these movements to minimise their ACd and maximise their performance. Aerodynamic position must be evaluated in real cycling locomotion, whether for the evaluation of A or ACd. We have developed two applications that are a real asset for the dynamic evaluation of aerodynamic drag (Ra) as they make the data analysis more accessible to coaches. Finally, although we have initiated a new method to assess ACd in the aerodynamic position by combining 3D scanning and computational fluid dynamics simulation, this method is also recommended for individualisation of cycling equipment.The seated cycling position can also be optimised by increasing the cyclists’ force effectiveness (FE), regardless of practice level or gender. This increase in FE is mainly due to a decrease in resistive force (Fres) during the upstroke phase of pedalling. Nevertheless, the cyclist should not pull on the pedal to generate propulsive torque because this strategy is counterproductive from an energy point of view. It would be interesting to extend our first study, which was set up in a laboratory, to the field to analyse the biomechanical adaptations of cyclists to the real conditions of locomotion. The differences observed in the laboratory, on level ground and over an uphill grade suggest that cyclists adjust their pedalling technique according to the conditions under which they are performing.Finally, studies of the standing cycling position show that cyclists increase their mechanical cost (MC) (+4.3% in the laboratory vs. +19% in the field) compared to the seated position; however, oxygen consumption was similar between the two positions. These mechanical losses (13 W in the laboratory vs. 49 W in the field) in the standing position are mainly due to increased rolling resistance coefficient (Crr), induced by the lateral sways of the bicycle and therefore torsion of the tyres. Because the observed mechanical losses are higher in the field than on the treadmill, other factors could contribute to this difference, such as Ra (~10 W), the equipment used by cyclists, the Crr of the road surface and the technique adopted. Also, the standing position induces an increase in MC to maintain constant speed when faced with uphill slope variations. Cyclists are therefore strongly recommended to reduce the increase of the MC in standing position compared to the seated position. This reduction in mechanical losses can be achieved by decreasing lateral sways and Ra
Scheller, Johannes. "Electroactive morphing for the aerodynamic performance improvement of next generation airvehicles." Phd thesis, Toulouse, INPT, 2015. http://oatao.univ-toulouse.fr/14479/1/scheller_partie_1_sur_2_2.pdf.
Full textBarelle, Caroline. "Modélisation dynamique du geste sportif à partir de paramètres posturaux : application à l'entraînement en ski alpin." Lyon 1, 2003. http://www.theses.fr/2003LYO10097.
Full textRoux, Élodie. "Pour une approche analytique de la dynamique du vol." Toulouse, ENSAE, 2005. http://www.theses.fr/2005ESAE0019.
Full textDubosc, Matthieu. "Modélisation hors adaptation des performances individuelles d'un doublet d'hélices contrarotatives." Thesis, Poitiers, 2016. http://www.theses.fr/2016POIT2255/document.
Full textWithin the scope of the European research project Clean Sky, Snecma builds a ground demonstrator of the concept engine Contra Rotating Open Rotor (CROR). Engine control system design requires knowing how each propeller will behave aerodynamically under the interaction of each other. The aim of this work is to design a predictive model of contra rotating propeller individual performance fitting in a thermodynamic cycle calculation environment. A coupling is proposed in order to represent the dual propellers thanks to isolated propeller behavior. It has been shown that by matching the isolated propellers thrust and torque to the doublet values, the good values of mutual induced velocities can be found. Hence contra rotating propellers individual performance can be reached with a good variation in parameters. In addition to that, in order to meet withthermodynamic cycle calculation environment requirements of rapidity and numerical robustness, performance is calculated from pre-generated propeller maps. One-dimensional approach is used to calculate mutual induced velocities from propellers thrust and torque. Contra rotating propellers individual performance calculation is an iterative process. The method developed gives the performance within a 5% relative error margin and is currently used for the design of the ground demonstrator control system
Arntz, Aurélien. "Civil aircraft aero-thermo-propulsive performance assessment by an exergy analysis of high-fidelity CFD-RANS flow solutions." Thesis, Lille 1, 2014. http://www.theses.fr/2014LIL10110/document.
Full textThe tools and methodologies currently used for the design of commercial aircraft have been initiated decades ago and are based on simplifying assumptions that become excessively ambiguous for highly-integrated propulsion devices for which traditional drag/thrust bookkeepings become inapplicable. Likewise, the growing complexity of civil aircraft requires a more global performance assessment which could take into account thermal management. As a consequence, a new exergy-based formulation is derived for the assessment of the aerothermopropulsive performance of civil aircraft. The output of the derivation process is an exergy balance between the exergy supplied by a propulsion system or by heat transfer, the mechanical equilibrium of the aircraft, and the exergy outflow and destruction within the control volume. The theoretical formulation is subsequently numerically implemented in a Fortran code named ffx for the post-processing of CFD-RANS flow solutions. Unpowered airframe configurations are examined with grid refinement studies and a turbulence model sensitivity analysis. The code is thereby validated against well-tried methods of drag prediction or wind-tunnel testings when available. Finally, the investigation of powered configurations demonstrates the ability of the approach for the performance assessment of configurations with aerothermopropulsive interactions
Engels, Thomas. "Numerical modeling of fluid-structure interaction in bio-inspired propulsion." Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4773/document.
Full textFlying and swimming animals have developed efficient ways to produce the fluid flow that generates the desired forces for their locomotion. These bio-inspired problems couple fluid dynamics and solid mechanics with complex geometries and kinematics. The present thesis is placed in this interdisciplinary context and uses numerical simulations to study these fluid--structure interaction problems with applications in insect flight and swimming fish. Based on existing work on rigid moving obstacles, using an efficient Fourier discretization, a numerical method has been developed, which allows the simulation of flexible, deforming obstacles as well, and provides enhanced versatility and accuracy in the case of rigid obstacles. The method relies on the volume penalization method and the fluid discretization is still based on a Fourier discretization. We first apply this method to insects with rigid wings, where the body and other details, such as the legs and antennae, can be included. After presenting detailed validation tests, we proceed to studying a bumblebee model in fully developed turbulent flow. Our simulations show that turbulent perturbations affect flapping insects in a different way than human-designed fixed-wing aircrafts. While in the latter, upstream perturbations can cause transitions in the boundary layer, the former do not present systematical changes in aerodynamic forces. We conclude that insects rather face control problems in a turbulent environment than a deterioration in force production. In the next step, we design a solid model, based on a one--dimensional beam equation, and simulate coupled fluid--solid systems
Fakher, El Abiari Salah Eddine. "Modélisation des régimes d'écoulements instationnaires rencontrés en turbomachine axiale." Ecully, Ecole centrale de Lyon, 1987. http://www.theses.fr/1987ECDL0007.
Full textMinelli, Andrea. "Optimisation de forme aéro-acoustique d'un avion d'affaires supersonique." Phd thesis, Université Nice Sophia Antipolis, 2013. http://tel.archives-ouvertes.fr/tel-00938396.
Full textBengherbia, Tarek. "Contribution à l'étude des performances d'un accélérateur à effet stato en régime sous-détonatif." Phd thesis, 2009. http://tel.archives-ouvertes.fr/tel-00491860.
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