Contribution to the description of rotating flow instabilities and inlet perturbations in axial flow compressors

A calculation method for the description of aerodynamic cascade instabilities and the phenomena of rotating flow separation in axial flow compressors was developed. The solution of the unsteady, two-dimensional flow in convergent-divergent channels with variable cross section is an initial value and boundary value problem. The integration of the equation system was performed with an explicit time-step method of second order. The calculated global pressure perturbation in a transonic axial flow compressor agrees with the measurements. The calculated periodically varying flow phenomena have a similar behavior to the observed rotating separations. The prediction capability of the calculation results was demonstrated. The quantitative evaluation of the stability analysis for a highly loaded rotor shows agreement with experimental data. The method seems to be too complicated for the calculation of multistage machines.