Determination of local bulk temperature based heat transfer coefficient in the channel with multiple inlets and multiple outlets

The accuracy of heat transfer coefficient of internal cooling channel is directly related to the selection of the fluid bulk temperature called T_b, and it is difficult to be directly measured in the test. As a result, a practical and precise method is needed to be developed for data processing. This paper investigates one theoretical derivation method and one practical experimental data processing method. The theoretical one is more precise but depends on much immeasurable flow field information. With some simplifications and corrections, the practical method is easy to calculate and the parameters involved are easy to measured. By dividing the channel into four kinds of segments, our methods are suitable for many kinds of channel. The energy balance method is used in the theoretical derivation method. The practical method is mainly based on local linear interpolation and the channel is divided into three parts that mainly influenced by mainstream flow, secondary flow or both two flows according to different mass flow ratios. The experimental data of the rotational turbine blade and corresponding numerical simulations show the superiority of this method in the aspect of accuracy, stability and applicability. In general, these two methods have their own characteristics and apply to different scenes, which makes them of great meaning and progressiveness.