Impinging jets have become an indispensable measure for cooling applications in gas turbine technology. The present study seeks to explore the flow field dynamics inside an enigine-relevant cooling passage of trapezoidal cross-section. The investigated geometry produces a highly complex flow field which was investigated employing particle image velocimetry (PIV). The experiments were accompanied by numerical simulations solving the Reynolds-averaged Navier–Stokes (RANS) equations with FLUENT using the low-Re k-ω-SST (shear stress transport) turbulence model. Additionally, time-resolved pressure measurements were performed utilizing Kulite pressure transducers. The spectral analysis of the transient pressure signal in conjunction with a proper orthogonal decomposition (POD) analysis of the PIV data allows for a detailed insight into the effects of geometric constraints on the fluid dynamic processes inside the geometry. The results are presented for a jet Reynolds number of 45,000 and display a qualitatively fair agreement between the experiments and numerical simulations. Nevertheless, the simulations predict flow features in particular regions of the geometry that are absent in the experiments. Despite the lack of conspicuous high energy modes, the flow was well suited for a POD analysis. Depending on the considered PIV plane, it could be shown that up to 25% of the flow field's total turbulent energy is contained in the first ten POD modes. Additionally, using the first 20 to 60 POD modes sufficed to reconstruct the flow fields with its governing features.