Studies on the Convective Heat Transfer from a Rotating Disk : 4th Report, Laminar Heat Transfer from a Disk with a Step-wise Discontinuity in Surface Temperature Rotating in Uniform Forced Stream

Abstract

The step function factor for laminar heat transfer from a disk rotating in uniform forced stream, with its surface temperature changing step-wise was analysed by the profile method based on the energy integral equation. The velocity profile in a laminar boundary layer changes complicatedly by the ratio of axial velocity to rotating one, but it was expressed by a single formula. On the other hand, the temperature profile was assumed by cubic polynomial. The step function factor was numerically obtained by HIPAC 103 electronic computer and then in view of the application of the technique of superposition, an empirical formulation of the step function factor was conducted. Its adequancy was confirmed by comparison with the exact similar solution for the case of the simple quadratic surface temperature distribution as a typical non-isothermal surface. Moreover, for the isothermal disk with an unheated part in center, the mean heat transfer coefficient was obtained by use of the step function factor.