Heat-Transfer Characteristics of the Rotational and Axial Flow Between Concentric Cylinders

Gazley, Carl

doi:10.1115/1.4012256

Cited by 32 publications

(13 citation statements)

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“…In the present research, the maximum rotational Reynolds number is 4500 (see Table 1), so according to identified five different regions for CT flow by Murai et al (2008), the flow region is turbulent wavy vortex flow (TWTF). On the other hand, in a simple CT flow Taylor vortices appear in the annulus gap when Taylor number reaches to critical Taylor number ( 3 1.7 10 cr Ta ) (Gazley Jr, 1958 ). Since in this work minimum Taylor number is greater than the critical Taylor number, the Taylor vortices undoubtedly appear inflow.…”

Section: Methodsmentioning

confidence: 65%

Numerical study of frictional drag reduction using micro-bubbles in a vertical Couette-Taylor system

Javadpour

Maryami

Kadivar

2022

ijpse

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In this work, we numerically study the reduction of frictional drag in a vertical Couette-Taylor system by using micro-bubbles. The silicon flow is in the annular gap between two concentric cylinders as the internal cylinder is rotating while the outer cylinder is stationary. Taylor vortices are formed between the cylinders and the rotational Reynolds number also varies from 700 to 4500. The carrier flow is silicone while air bubbles are constantly injected into the carrier phase at the bottom of cylinders and rise through the flow. By employing a discrete phase model and Euler-Lagrange approach, we investigate a two-phase turbulent flow. In this way, we study the distribution of the bubbles through the flow, which is acquired using numerical modeling. Our numerical results are in good agreement with the experimentally reported data for different values of Reynolds numbers. We also investigate the effect of injected air with a constant flow rate on the skin friction drag and on the drag coefficient ratio. Our numerical results illustrate a reduction of drag about 36% when microbubbles are injected into the system. This reduction can be achieved by the effect of the bubbles on the density of the fluid and transformed momentum.

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Section: Methodsmentioning

confidence: 65%

Numerical study of frictional drag reduction using micro-bubbles in a vertical Couette-Taylor system

Javadpour

Maryami

Kadivar

2022

ijpse

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“…The thermal conduction in the air gap is carried out in a centrifugal force field, and the air convection in a cylindrical surface has been studied in related references. 31–37 The coefficient in the gap is calculated byhere δ is the air-gap length; Nu represents Nusselt number, which can be calculated by 33 where r1 is the rotor radius (m); β represents empirical coefficient considering surface roughness; and Re is Reynolds number of the airflow in the air gap, which is indicated asAnd in Eq. 37, Recr represents the critical value of Reynolds number, which is written as 38 …”

Section: Heat Transmission Mechanism In the Motorized Spindlementioning

confidence: 99%

An optimized thermal network model to evaluate the thermal behavior on motorized spindle considering lubricating oil and contact factors

Chen

2022

Proceedings of the Institution of Mechanical Engineers, Part C:

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During the operation of the high-speed motorized spindle, the heating of motorized spindle components can cause thermal deformations, which worsens the work performance and shortens the life expectancy of the motorized spindle. In response to the above behaviors, the thermal network model for the motorized spindle in this investigation was built in which the lubricating oil properties and contact characteristics were considered. Next, according to Kirchhoff's energy balance principle, the theoretical equations of steady-state temperature were established, and the temperature rise of the motorized spindle was obtained by Newton-Raphson method. Lastly, the influences of speed, cooling water flow rate, air flow rate and other variables on the temperature were analyzed and verified by the experiment. The results show that the thermal network model including lubricating oil and contact factors can predict the temperature rise of motorized spindle accurately, which provides some references and suggestions in motorized spindle design.

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“…However, the results from the literature give some uncertainty for what the critical T a m is. For Hwang [26], Hayase [25] and Gazley [16] the instability onset seems to take place for T a m < T a c . Whereas according to the data from Bouafia [21], [23], the vortices appear for higher values of modified Taylor number, and in particular the critical T a m = 3, 900 is measured.…”

Section: Literature Reviewmentioning

confidence: 99%

“…• Laminar flow • Laminar flow plus Taylor vortices • Turbulent flow plus Taylor vortices • Turbulent flow The presence of salient poles on the rotor side considerably changes the boundary conditions of the problem since the air flow is no longer driven by a continuous surface, and recirculations develop in the slots. This affects the critical value for the onset of instability and the rate of convective heat transfer between the rotor and stator surface, which may increase by up to 50% [16]. Thus, the classical correlations from the literature (e.g.…”

Section: Introductionmentioning

confidence: 99%

Air-gap convection in a switched reluctance machine

Romanazzi

Howey

2015

2015 Tenth International Conference on Ecological Vehicles and Renewable Energies (EVER)

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Switched reluctance machines (SRMs) have recently become popular in the automotive market as they are a good alternative to the permanent magnet machines commonly employed for an electric powertrain. Lumped parameter thermal networks are usually used for thermal analysis of motors due to their low computational cost and relatively accurate results. A critical aspect to be modelled is the rotor-stator air-gap heat transfer, and this is particularly challenging in an SRM due to the salient pole geometry. This work presents firstly a review of the literature including the most relevant correlations for this geometry, and secondly, numerical CFD simulations of air-gap heat transfer for a typical configuration. A new correlation has been derived: Nu = 0.181 Ta 0.207 m . This paper is part of the ADvanced Electric Powertrain Technology (ADEPT) project which is an EU funded Marie Curie ITN project, grant number 607361. Within ADEPT a virtual and hardware tool are created to assist the design and analysis of future electric propulsion, especially within the context of the paradigm shift from fuel powered combustion engines to alternative energy sources (e.g. fuel cells, solar cells, and batteries) in vehicles like motorbikes, cars, trucks, boats, planes. The design of these high performance, low cost and clean propulsion systems has stipulated an international cooperation of multiple disciplines such as physics, mathematics, electrical engineering, mechanical engineering and specialisms like control engineering and safety. By cooperation of these disciplines in a structured way, the ADEPT program provides a virtual research lab community from labs of European universities and industries [1].

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Heat-Transfer Characteristics of the Rotational and Axial Flow Between Concentric Cylinders

Cited by 32 publications

References 0 publications

Numerical study of frictional drag reduction using micro-bubbles in a vertical Couette-Taylor system

Numerical study of frictional drag reduction using micro-bubbles in a vertical Couette-Taylor system

An optimized thermal network model to evaluate the thermal behavior on motorized spindle considering lubricating oil and contact factors

Air-gap convection in a switched reluctance machine

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