The paper presents a numerical and experimental investigation of the effect of incindence angle offset in a two-dimensional section of a flat blade cascade in a high-speed wind tunnel. The aim of the current work is tp determine the aerodynamic excitation forces and approximation of the unsteady blade-loading function using a quasi-stationary approach. The numerical simulations were performed with an in-house finite-volume code built on the top of the OpenFOAM framework. The experimental data were acquired for regimes corresponding to the numerical setup. The comparison of the computational and experimental results is shown for the static pressure distributions on three blades and upstream and downstream of the cascade. The plot of the aerodynamic moments acting on all five blades shows that the adjacent blades are significantly influenced by the angular offset of the middle blade.

This paper presents a very effective interference technique for the sensing and researching of compressible fluid flow in a wind tunnel facility. The developed technique is very sensitive and accurate, yet easy to use under conditions typical for aerodynamic labs, and will be used for the nonintrusive investigation of flutter in blade cascades. The interferometer employs a high-speed camera, fiber optics, and available “of-the-shelf” optics and optomechanics. The construction of the interferometer together with the fiber optics ensures the high compactness and portability of the system. Moreover, single-shot quantitative data processing based on introducing a spatial carrier frequency and Fourier analysis allows for almost real-time quantitative processing. As a validation case, the interferometric system was successfully applied in the research of supersonic compressible fluid discharge from a narrow channel in a wind tunnel. Density distributions were quantitatively analyzed with the spatial resolution of about $50 \mathsf{\mu }\mathrm{m}$. The results of the measurement revealed important features of the flow pattern. Moreover, the measurement results were compared with Computational Fluid Dynamics (CFD) simulations with a good agreement.

Flow separation in rocket nozzles has been studied mostly under sea-level conditions, which fail to take into account changes in ambient density and ambient pressure during the flight of a rocket. In the present study, numerical analysis is conducted of flow characteristics within a truncated ideal contour (TIC) nozzle to investigate the influence of ambient density and pressure on flow separation. Six different altitudes from a typical flight are considered, from a very low altitude to a high altitude. The flow is analyzed by varying the nozzle pressure ratios corresponding to these altitudes. Both cold flow and hot flow simulations are conducted. The locations of separation positions at various altitude conditions are accurately captured and are found to be in good agreement with experimental results. The results of the study establish that for a given nozzle pressure ratio, the flow separation point is shifted upstream with increasing altitude. This clearly points to a dependence of separation position on the altitude of operation for TIC rocket nozzles.