Structural features and surface heat transfer associated with a row of short-hole jets in crossflow

Abstract

Abstract Surface streak experiments coupled with flow visualization and numerical simulations were used to investigate short length-to-diameter injection holes for geometries of interest to the gas turbine industry. The flow field results were also related to measured surface heat transfer coefficients in the downstream region of the jets. Geometric surface topology maps inferred from “oil and lampblack” surface streak experiments give insights into the flow field, as well as boundary layer disruption, and ultimately the convective heat transfer coefficient enhancement in the wake region of the jets. A secondary counter-rotating vortex pair (CRVP) with the opposite sense of rotation as the well-documented main CRVP is present in some configurations and is found to noticeably enhance the attachment event in the wake region and correspondingly enhance the convective heat transfer coefficient. The separation and attachment regions corresponding to the separation and attachment of boundary layer fluid brought about by jet–crossflow interaction was found to strongly affect the heat transfer on the surface downstream of the jets. The relative strength of the attachment events, and therefore the effect on h , is dependent on the trajectory of the CRVP, presence or absence of the secondary CRVP, and the attachment of crossflow fluid that has accelerated around the issuing jet. In addition to providing information about the crossflow boundary layer disruption, the surface topological results relate the signature of the surface shear stress to the coherent flow structures in the flow field being investigated.