Heat transfer from a non-isothermal rotating rough disk subjected to forced flow

摘要

This communication aims to report heat transfer characteristics from a non-isothermal wavy disk rotating in a forced flow. The primary objective of this kind of studies is to seek a suitable mechanism for the quick removal of heat energy from a rotating disk surface. The achievement of an efficient mechanism which ensures a further higher rate of heat transfer is a fundamental goal in such studies. In this regard active and passive techniques are of fundamental importance whereby the current study utilizes a combination of both. There are three key elements, namely, the nonuniform disk temperature; surface roughness, and a radial free flow, which are responsible for the augmentation of the heat transfer. The analysis has been carried out for a variety of fluids depicting the increased rate of heat transfer due to a variation of these different elements. In doing so, the local and global heat transfer rates are manipulated in order to obtain a clear picture of the heat transfer process at a corrugated disk. The considered rough non-isothermal disk (with two sinusoids) rotating in the uniform stream of air (Pr = 0.71) leads to a significant (about 263%) enhancement in the overall heat transfer rate compared to that of a flat free rotating disk having surface temperature as quatratic function of the radial coordinate. Moreover, some threshold values (which correspond to seizing the heat transfer process) of the used power-index of the disk temperature (T_w — T_∞ = c_0r~(n*)) are also identified which are observed to vary slightly due to the surface irregularities and the relative motion of fluid and disk.