General Methodology Prior to a disc

General Methodology Prior to a discussion as to the validation of the model, the general procedure is presented in the following subsection. The particular novelty of the method pertains to its use in rapidly ascertaining the cooling performance of a double-wall geometry based on the calculation of the various thermal resistances. In the most general case, this relies upon the use of correlative data and empirical observations. Take, for example, the impingement zone heat transfer coefficient, necessary in calculating thermal resistance R6. Many correlations exist to determine Nui based solely on the geometry and impingement jet Reynolds number, see for example [19]–[21]. Consequently, an approximate value for this heat transfer coefficient can be quickly obtained. Similarly, correlations exist for pedestals in crossflow at varying Reynolds numbers [22]. Other studies, such as those by Elmukashfi et al. [12] have discussed the appropriate use of various correlations over varying surfaces of a double- wall geometry based on sole knowledge of the geometry and impingement jet Reynolds number. Similarly, Gillespie [23] discusses the respective cooling attributes of various surfaces within a turbine blade, accounting for both the respective Nusselt number augmentations, along with area of cooling effect. Finally, the respective heat transfer coefficient augmentation that results from cooling films at varying blowing ratios is also documented in the literature (see for example Ammari et al. [24]). Consequently, a variety of methods exist which allow the determination of the various surface heat transfer coefficients to occur, thus permitting thermal resistances R1, R2, R4, R6, and R 7 to be calculated. The two conduction resistances, R3 and R5, require only knowledge of the material thermal conductivity and pedestal geometry for calculation. Thus, with knowledge of the value of resistors R1 – R7, the final three, amalgamated, parallel resistors R8 – R10, can be obtained.