Numerical simulation of film cooling with coolant supply through a nozzle of triangular shape with a step

The paper presents the numerical simulation results for a near-wall film cooling with gas ejection through a nozzle shaped as a cavity with triangular cross section (with a backward facing step). The backward facing step induces the main flow detachment and generates coherent vortex structures with a constant vortex-shedding frequency (in the zone of mixing with the coolant jet). These vortex structures interact with the wall and improve the coolant spreading in the horizontal direction. This also improves the jet flow attachment to the surface at high blowing ratios. The cavity’s triangular shape reduces the generation of streamwise vortices that separate the near-wall flow from the surface. The study was conducted for a wide range of coolant blowing ratios. The wall boundary conditions were adiabatic. We determined the injection parameters range suitable for practical applications of the proposed nozzle design. The proposed flow model has a specific vortex shedding frequency and is sensitive to the external forcing at this frequency. Thus, the model is a prototype of an active control system for film cooling.