Analysis of Swirl Number Effects on Effusion Flow Behavior Using Time-Resolved Particle Image Velocimetry

Abstract

The analysis of the interaction between the swirling and liner film-cooling flows is a fundamental task for the design of turbine combustion chambers since it influences different aspects such as emissions and cooling capability. Particularly, high turbulence values, flow instabilities, and tangential velocity components induced by the swirlers deeply affect the behavior of effusion cooling jets, demanding for dedicated time-resolved near-wall analysis. The experimental setup of this work consists of a non-reactive single-sector linear combustor test rig scaled up with respect to engine dimensions; the test section was equipped with an effusion plate with standard inclined cylindrical holes to simulate the liner cooling system. The rig was instrumented with a 2D Time-Resolved Particle Image Velocimetry system, focused on different field of views. The degree of swirl is usually characterized by the swirl number, Sn, defined as the ratio of the tangential momentum to axial momentum flux. To assess the impact of such parameter on the near-wall effusion behavior, a set of three axial swirlers with swirl number equal to Sn = 0.6 − 0.8 − 1.0 were designed and tested in the experimental apparatus. An analysis of the main flow by varying the Sn was first performed in terms of average velocity, RMS, and Tu values, providing kinetic energy spectra and turbulence length scale information. Following, the analysis was focused on the near-wall regions: the effects of Sn on the coolant jets was quantified in terms of vorticity analysis and jet oscillation.

Swirling flow field reconstruction and cooling performance analysis based on experimental observations using physics-informed neural networks

“…In addition, another challenge for numerical simulation was that it was always difficult to obtain the expected results when the boundary conditions were unknown or deviated from the reality, which would always be applied when the boundary conditions were highly complex. Therefore, experimental investigations such as hot wire (Vu and Gouldin, 1982), laser Doppler velocimetry (Brum and Samuelsen, 1987), laser anemometry (Syred et al, 1994), and planar particle image velocimetry (PIV) (Andreini et al, 2014;Lenzi et al, 2022) could provide more accurate and reliable reference data, without knowing the boundary conditions. Besides for the flow field diagnosis, the cooling performance diagnosis of the common cooling design in the combustor, such as effusion cooling, slot cooling, was also widely conducted because of its most intuitive display of the cooling performance affected by the swirling flow (Andreini et al, 2014(Andreini et al, , 2015(Andreini et al, , 2017.…”