The purpose of this research was a proof of concept using a fan motor stator as transducer to monitor motor rotor and attached axial fan for mechanical motion. The proof was to determine whether bearing faults and fan imbalances could be detected in vane-axial fans using Motor Electrical Signature Analysis (MESA). The data was statistically analyzed to determine if the MESA systems could distinguish between baseline conditions and discrete fault frequencies for the three test conditions: bearing inner race defect, bearing outer race defect, and fan imbalance. The statistical conclusions for these proofs of concept were that MESA could identify all three faulted conditions.

Dans le contexte des avions plus électriques, le potentiel de récupération d'énergie de ventilateurs de refroidissement embarqués est étudié. Ces compresseurs conventionnels, utilisés uniquement au sol, fonctionnent en autorotation libre en vol. Dans cette dernière configuration, appliquer un couple donné sur l'arbre permet de récupérer de l'énergie électrique, le ventilateur fonctionne alors en autorotation chargée (mode turbine). Cependant, ces géométries conventionnelles obtiennent de faibles rendements turbine, causés par des incidences fortement négatives conduisant à des décollements massifs. Il est alors nécessaire de concevoir une machine axiale réversible capable de fonctionner de manière duale en mode compresseur et turbine, avec une performance élevée dans les deux cas. Ce nouveau concept permet de capitaliser l’équipement tout au long de la mission. Dans cette étude, l'adéquation de l'approche quatre-quadrants et du formalisme psi-phi à propos du mode dual de turbomachines est soulignée, au détriment des représentations classiques séparant les performances compresseur et turbine. Une analyse du fonctionnement du mode compresseur à l'autorotation chargée a permis de mettre en évidence les propriétés génériques des écoulements d'autorotation ainsi que ce qui fait la spécificité des machines duales. Les mécanismes de l’écoulement et les paramètres géométriques impactant la performance le long de la ligne de fonctionnement ont également été identifiés. Le concept de machine duale est validé grâce aux grands rendements obtenus en essais. Enfin, une géométrie optimisée est proposée et des recommandations liées au design de machines duales sont données. / In 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.

Vehicle electrification plays a significant role in the effort to reduce the environmental impact of the automotive industry. Scania is one of the leading manufacturers ofheavy vehicles which is currently moving towards a sustainable transport system by manufacturing a new generation of heavy vehicles powered by batteries. Oneof the major concerns with these vehicles is related to the noise generated by the electric axial fans used in the cooling system. This project was conducted with thepurpose of investigating the factors that positively affect both noise and performance in the electric fans. Based on two different blade design methods and several noisecontrol techniques, 11 fan models were developed. The fan models created with design method 1 are equipped with cambered-plate blades, while the models madewith design method 2 consist of airfoil-shaped blades. Moreover, the performance of these models was analyzed by using theoretical methods and Computational FluidDynamics (CFD). In addition, two empirical approaches were used to estimate the acoustic energy emitted by the fan models. Furthermore, the developed modelswere compared with two commercially available fans. It was found that both design methods provide similar performance in low pressure differences. On the other hand,the efficiency and acoustic energy are influenced by the choice of the noise control methods. / Fordonselektrifiering har en väsentlig roll i arbetet med att minska bilindustrins miljöpåverkan. Scania är en av de ledande tillverkarna av tunga fordon som för närvarandegår mot ett hållbart transportsystem, genom att tillverka en ny generation tunga fordon drivna med batterier. Ett stort bekymmer med dessa fordon är relaterattill det ljud som genereras av de elektriska axialfläktarna som används i kylsystemet. Detta projekt genomfördes i syfte till att undersöka de faktorer som positivtpåverkar både buller och prestanda hos de elektriska fläktarna. Baserat på två olika bladdesignmetoder och flera brusstyrningstekniker, utvecklades 11 fläktmodeller.Fläktmodellerna som är utformade med konstruktionsmetod 1 är utrustade med krökformade plattor, medan modellerna som skapades med designmetod 2 bestårav vingprofil blad. Dessutom analyserades prestandan för dessa modeller med användning av teoretiska metoder och strömningsmekaniska beräkningar. Ytterligaretvå empiriska tillvägagångssätt användes för att uppskatta den akustiska energin som släppts ut av fläktmodellerna. Utöver det jämfördes de utvecklade modellernamed två kommersiellt tillgängliga fläktar. Detta visade att båda konstruktionsmetoderna resulterar i liknande prestanda vid lågtrycksskillnader, däremot påverkasverkningsgraden och den akustiska energin av valet av brusstyrningsmetoder.

Recent experimental achievements in active noise control (ANC) for cooling fans have used near-field error sensors whose locations are determined according to a theoretical condition of minimized sound power. A theoretical point source model, based on the condition previously stated, reveals the location of near-field pressure nulls that may be used to optimize error sensor placement. The actual locations of these near-field pressure nulls for both an axial cooling fan and a monopole loudspeaker were measured over a two-dimensional grid with a linear array of microphones. The achieved global attenuation for each case is measured over a hemisphere located in the acoustic far field of the ANC system. The experimental results are compared to the theoretical pressure null locations in order to determine the efficacy of the point source model. The results closely matched the point source model with a loudspeaker as the primary source, and the sound power reduction was greatly reduced when error sensors were placed in non-ideal locations. A weakness of the current near-field modeling process is that a point monopole source is used to characterize the acoustic noise from an axial cooling fan, which may have multipole characteristics. A more complete characterization of fan noise may be obtained using a procedure based on the work of Martin and Roure [J. Sound Vib. 201 (5), 577--593 (1997)]. Pressure values are obtained over a hemisphere in the far field of a primary source and the contributions from point source distributions up to the second order, centered at the primary source, may be calculated using a multipole expansion. The source information is then used in the aforementioned theoretical near-field calculation of pressure. The error sensors are positioned using the complete fan characterization. The global far-field attenuation for the multipole expansion model of fan noise is compared to that of previous experiments. Results show that the multipole expansion model yields a more accurate representation the near field, but is not successful in achieving greater sound power reductions in the far field.