Pseudo-shock system structure in rectangular Laval nozzles with gaps

A detailed experimental investigation of the influence of small gaps on a pseudo-shock system has been performed for different gap sizes and pressure ratios p02/p01. In addition to schlieren images that only provide integral information of the total light deflection through the test section, 3-D numerical data was additionally used to investigate 3-D phenomena of the shock system. The combination of experimental and numerical techniques considerably increased the understanding of the underlying mechanisms that cause the change in structure and position of the pseudo-shock system when increasing the gap size