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The jet interaction flow field generated by a subsonic circular jet exhausting into a transonic cross-flow over a convergent–divergent nozzle is investigated using numerical simulations. The simulations use the three-dimensional large eddy simulation and Reynolds-averaged Navier–Stokes equations coupled with the standard k-ε turbulence model. The numerical method is verified via cold-flow and schlieren experiments. The vortex structures are identified via the Liutex–Omega method, and the flow details of various pressure ratios and injection angles are studied. The numerical results capture the main vortex structures of a jet in cross-flow, such as the trailing upper vortex and trailing major vortex. The trailing top vortex, which is difficult to capture, and a new vortex structure, named the longitudinal shear vortex, are both observed when the momentum flux is sufficiently large. This study identifies the longitudinal shear vortex for restricted flow, which to some extent facilitates the mixing of the cross-flow and the jet. The results presented in this paper indicate that the vortex structure distribution of a subsonic jet and transonic cross-flow in the restricted region can be optimized. The main vortex structures are analyzed in detail.

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To develop an effective suction slot arrangement, computational fluid dynamics simulation software and a high subsonic compressor cascade were used to simulate different suction slots. Based on the effects of various suction slots on the cascade performance under various operating conditions, a novel segmented suction slot structure Seg3 was proposed. The results of the study revealed that in the vicinity of the operating conditions ( incidence ≤ 4 ° ), a full-blade height suction slot should be installed at least 5% of the chord length downstream of the corner separation point to effectively remove the separation. For small and medium incidences, the best performance was observed for suction slot SS5, which was located at 60% of the chord length downstream of the leading edge. Analyzing the effects of SS5 and Seg3 on the cascade performance revealed that when the incidence was less than 4°, the reductions in the total pressure loss coefficients for ζsuc of SS5 and Seg3 both exceeded 8.2%. When the incidence was 4° or greater, the ζsuc increased slightly for SS5, whereas it decreased for Seg3, and the ζsuc was reduced. For a 3° incidence, for example, Seg3 reduced the ζsuc and passage blockage by 12.74% and 8.41%, respectively, and increased the static pressure rise coefficient by 18.55% from the baseline values. Thus, the segmented suction slot proposed in this paper outperformed conventional full-blade height suction slots.