<p style="margin: 0cm 0cm 0pt">Rotating disk is one of the important components of many rotating machineries such as clutches, retarders, disk brakes, and even computer-disk drives, etc. When these machineries are operating, heat will be generated due to the friction loss between the working elements and the surrounding working fluid. The heat will be built up if it can not be taken away by heat convection with surrounding cooling air or liquid so that the working elements is overheated, which results in a lower efficiency and shorter service life of these machineries. Therefore, the convective heat transfer around rotating disks is concerned highly so that the cooling systems can be designed appropriately to ensure that the designed rotating machineries can operate stably and reliably without overheating.</p><p style="margin: 0cm 0cm 0pt">Some literatures on the convective heat transfer of free rotating disks are reported and corresponding empirical or analyzing formulas for heat transfer coefficient were put forward. Among these reported formulas, the formula proposed by Dorfman (Hydrodynamic resistance and the heat loss of rotating solids, Oliver and Boyd, Edinburgh, 1963) is widely adopted by researchers and engineers. However, this formula was derived based on the case of single disk rotating in an infinite (or large) space, there are some limitations when it is applied to estimate the convective heat transfer of multiple coaxial rotating elements separated by limited distance or rotating disks installed in a finite space, such as transmissions and retarders. While relatively not enough studies of heat transfer coefficient on single rotating disk in a limited space or pair of parallel disks separated by a limited distance in an infinite space are available. In this paper, a series of direct numerical simulations were carried out to study the rotational convective heat transfer performance of a single disk in finite space and a coaxial double disks in large space. The influences of the space domain where the disk is located and the distance between two disks on the heat transfer performance were analyzed. The results show that for the convective heat transfer of a single disk in the finite space domain, when the structural parameters of the disk are fixed, the convective heat transfer coefficient on the disk surface decreases with the decreases of the housing dimension and the disk radius, regardless of whether the flow is laminar or turbulent. For the convective heat transfer of a coaxial double disks in large space, the convective heat transfer coefficient decreases with the decrease of the distance between two disks. By comparing the numerical simulation results with the estimated results from the Dorfman’s formula, the estimation errors and the applicable conditions of the formula in the case of limited space are obtained. Furthermore, a correction factor is given based on the Dorfman’s formula. These results are helpful for engineers to improve the simulation accuracy of thermal analysis of rotating machineries.</p>

Influences of Housing Dimension and Disk Gap on Convective Heat Transfer Performance of Rotating Disks

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

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