Heat transfer and pressure loss performance for families of partial length pin fin arrays in high aspect ratio rectangular ducts

Arrays of short pin fins are frequently used in narrow high aspect ratio channels to provide heat transfer augmentation for internal cooling of gas turbine engine airfoils. One characteristic of such arrays is that the amount of additional heat transfer area created by the installation of pins is small. Potential increases in performance may be accomplished through removal of a portion of the length of the pins, thereby adding surface area from the pin cross section and reducing flow blockage. For a given pin spacing pattern, such partial length pin fin arrays can be arranged in a large number of variations, both with and without accompanying rib roughness elements. The present paper is a summary of the results of an extensive experimental program which fabricated more than twenty new arrangements to provide designers with additional options. With heat transfer alone as the performance criteria, no partial length pin arrays were found that outperformed the corresponding full length pin array. However, with both heat transfer and pressure loss considered, several new partial length pin arrays were found to be superior.