Estimation of windage losses inside very narrow air gaps of high speed electrical machines without an internal ventilation using CFD methods

Nachouane, Ayoub Ben; Abdelli, Abdenour; Friedrich, Guy; Vivier, Stéphane

doi:10.1109/icelmach.2016.7732904

Cited by 30 publications

(13 citation statements)

References 17 publications

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“…Some researchers believe that Cf is related to both Re and Ta, while Yamada [14] believes that Cf is only related to Re. And Nachouane [9] believes that when Taylor vortices do not occur, Cf is only related to Re, but when Ta goes higher, Cf is independent to Re, only related to Ta. This is because it is difficult to keep Ta unchanged when testing different Re, so the previous studies were under different range of Ta.…”

Section: Related Workmentioning

confidence: 99%

“…When Ta increases further to 1.6×10 5 , Taylor vortices begin to interact each other. Literature [9] defined two intervals Ta1 and Ta2 to distinguish laminar, partial turbulence and totally turbulence stages. In this paper, Ta1 is around 1700, Ta2 is around 1.6×10 5 , which matches the previous studies.…”

Section: Angular Velocity ωmentioning

confidence: 99%

“…The effect of Ta has been studied by other scholars. A B Nachouane [9], analyzed and fitted Cf under different Ta caused by different angular velocity, linear velocity and air gap length, but the influence of axial ventilation on Taylor vortices has not been studied. According to the existing research results [11][12][13], researchers commonly use linear superposition to calculate total windage loss caused by axial ventilation and tangential friction, which brings errors.…”

Section: Introductionmentioning

confidence: 99%

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Analysis of axial windage loss in air gap of high-speed motors under high Taylor number

Song

Cao

Zhong³

et al. 2023

J. Phys.: Conf. Ser.

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In the field of ultra-high-speed motors, windage loss rises rapidly with the increase of rotational speed, and even becomes the main part of motor loss. However, most researches of windage loss are based on empirical formulas, which has a narrow scope of application. These formulas could not guarantee the accuracy when calculating large Taylor number flow in high-speed motor air gap, especially under axial ventilation condition. This paper focuses on the interaction between Taylor vortices and axial flow, analyses the influence of Taylor number on the behaviour of Taylor vortices and windage loss under non-axial and axial ventilation. First, another form of friction coefficient related to rotation speed is proposed using dimension analysis. Second, the scale of Taylor vortices is estimated and how it affects windage loss is discussed. Finally, a deceleration experiment taking a 250krpm induction motor is used to verify the accuracy of the proposed windage loss model.

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Section: Related Workmentioning

confidence: 99%

Section: Angular Velocity ωmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Analysis of axial windage loss in air gap of high-speed motors under high Taylor number

Song

Cao

Zhong³

et al. 2023

J. Phys.: Conf. Ser.

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“…Afterward, to improve the prediction accuracy and enlarge the application range of C f , Yamada, Vrancik, and Bilgen 25,26 also built the model of C f . And the result of Bilgen model is closest to numerical and experimental data compared to the other three models under ambient air conditions, based on the studies described by Deng et al 14 and Sarri.…”

Section: Introductionmentioning

confidence: 99%

Action mechanism of axial flow on windage loss in open shaft‐type gap with CO₂

Hu,

Deng,

Liu

et al. 2023

Energy Science & Engineering

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The windage loss in rotor‐stator gap has an important effect on rotating machinery, especially with higher rotational speed and fluid density. However, the mechanism of axial flow on windage loss in open shaft‐type gap is hardly studied in most literature. To clarify it, the influences of axial Reynolds number Reu and rotational Reynolds number Reω on skin friction coefficient Cf are investigated, and flow characteristics are analyzed with different gap geometry, radius ratio η. First, the results reveal that the Cf remains constant when Reu is less than 2.8 × 104 and increases rapidly as Reu when Reu ≥ 2.8 × 104, which indicates that the effect of axial velocity u on Cf is negligible for low Reu. The positive relative deviation Δ suggests that the axial flow makes windage loss and Cf rise. Besides, a larger number of Taylor vortexes fill with gap when the effect of the centrifugal force is larger than that of the inertial force, but they gradually disappear as Reu. Subsequently, the Cf and Δ increase as η, highlighting that the effect of u on windage loss and Cf is more prominent for larger η. The fact that vorticity near walls is larger than that at the center of gap reveals that windage loss arises from the interaction between walls and fluid rather than the dissipation with fluid itself. Finally, the model of Cf in shaft‐type gap is proposed in different Reω ranges based on numerical results, and the maximum sum of squares error of 1.02 × 10−5 and minimal R2 of 0.969 satisfy the requirement of fitting accuracy and indicate that the fitting model can accurately predict Cf. The conclusions significantly help predict windage loss in open shaft‐type gap with axial flow, and further improve the design for generators of supercritical CO2 turbine‐alternator‐compressor unit.

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“…Este tipo de pérdidas son las ocasionadas por la fricción relativa entre el aire contenido en la cámara de vacío y la superficie exterior del rotor de la máquina. El proceso de cálculo de las pérdidas aerodinámicas es complejo y muy utilizado en los artículos de investigación relacionados con motores eléctricos [212]- [217]. En dichos artículos, se establecen ecuaciones analíticas que modelan las pérdidas en función de la geometría de la máquina y de la velocidad de giro de esta.…”

Section: Pérdidas Aerodinámicasunclassified

Diseño optimizado de una máquina de reluctancia conmutada aplicada a un sistema de almacenamiento de energía para integración de energías renovables

Miranda¹

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Diseño optimizado de una máquina de reluctancia conmutada aplicada a un sistema de almacenamiento de energía para integración de energías renovables P á g i n a | v AGRADECIMIENTOSCorría el año 2015 cuando decidí embarcarme en el mundo de las tesis doctorales y concretamente en el mundo del diseño de máquinas de reluctancia. Después de aquella decisión se sucedieron una lista de cosas: la primera de las tareas fue colocarme en lo que se denomina "umbral del conocimiento" o como se conoce a pie de calle ponerse al día estudiando. Esta tarea pensaba que era rápida y simple, pero conlleva mucho trabajo de investigación, lectura de artículos, estudio de teoría, etc.; algo que al principio supuso un suplicio y que se ha convertido en un disfrute. Después de enseñaros como fueron mis andanzas en el año 2015 y las alegrías y penas por partes desiguales de mi aventura en el mundo de la investigación, me encuentro ahora sentado delante de este apartado, recordando cada una de las personas y de las historias que me han ocurrido y que han aportado su granito de arena para que este documento fructifique. Hay que reconocer que me está costando más redactar este apartado que toda la tesis y no sé si es por qué no me quiero dejar nada en el tintero o porque no sabría cómo dar las gracias a cada una de las personas que, como decía antes, han aportado su granito de arena en ayudar a andar el camino de la investigación hasta el día de hoy.Diseño optimizado de una máquina de reluctancia conmutada aplicada a un sistema de almacenamiento de energía para integración de energías renovables P á g i n a | xiii ÍNDICE DE FIGURASDiseño optimizado de una máquina de reluctancia conmutada aplicada a un sistema de almacenamiento de energía para integración de energías renovables Figura 1.1. Comparación de diferentes tecnologías de almacenamiento en función de la capacidad de almacenamiento (tiempo) y de la potencia de intercambio [4].

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Estimation of windage losses inside very narrow air gaps of high speed electrical machines without an internal ventilation using CFD methods

Cited by 30 publications

References 17 publications

Analysis of axial windage loss in air gap of high-speed motors under high Taylor number

Analysis of axial windage loss in air gap of high-speed motors under high Taylor number

Action mechanism of axial flow on windage loss in open shaft‐type gap with CO₂

Diseño optimizado de una máquina de reluctancia conmutada aplicada a un sistema de almacenamiento de energía para integración de energías renovables

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Estimation of windage losses inside very narrow air gaps of high speed electrical machines without an internal ventilation using CFD methods

Cited by 30 publications

References 17 publications

Analysis of axial windage loss in air gap of high-speed motors under high Taylor number

Analysis of axial windage loss in air gap of high-speed motors under high Taylor number

Action mechanism of axial flow on windage loss in open shaft‐type gap with CO2

Diseño optimizado de una máquina de reluctancia conmutada aplicada a un sistema de almacenamiento de energía para integración de energías renovables

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Action mechanism of axial flow on windage loss in open shaft‐type gap with CO₂