A new distortion evaluation method based on geometric association for arbitrary cross-sectional shape of inlet

The distortion flowfields generated by convoluted inlets are major factors that compromise the stability and performance of the downstream engine. For better understanding the distortion evolution, the total pressure distortion from the arbitrary cross-sectional shape of inlets was efficiently calculated based on geometric association. First, the Poisson equation was solved to generate a grid on the original, arbitrarily shaped, non-circular plane; then, a previously simulated dataset was used as a sample to interpolate the grid, whose nodes were mapped into a circular plane according to the principle of equal areas of rings and blocks. Finally, the traditional distortion descriptors were used to evaluate the distortion of the newly generated plane. The proposed method guarantees that both the total pressure recovery coefficient of the transformed crossflow plane and the contribution of this coefficient from each grid unit remain constant. This method was also applied for the flowfield analysis of serpentine and submerged inlets; the various forms of distortion along the ducts were studied. The total pressure distribution coefficient DC(60) distributions along the internal flow direction differed completely under different exit Mach numbers and their drastic changes were located at the severe bends or expansions of the inlet profile. Such innovation in distortion evaluation can provide insights into flow distortion in various inlets and enable better integration between inlets and engines.