STEADY AND UNSTEADY AERODYNAMIC CHARACTERISTICS OF SUPERSONIC THROUGH-FLOW FAN CASCADE

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・The computation program to predict the steady performance of a supersonic through-flow fan on the basis of the linearized three-dimensional steady lifting surface theory for a rotating annular cascade was developed. A parametric study of the steady performance in correlation with the axial Mach number, rotating speed, boss ratio, number of blades and blade profile was conducted.・The computation program to predict the unsteady aerodynamic characteristics of a supersonic through-flow fan on the basis of the Iinearized three-dimensional unsteady lifting surface theory for a rotating annular cascade was developed. A parametric study of the aerodynamic instability of blade vibration in correlation with design parameters was conducted. The pure bending motion under zero mean loading is always aerodynamically damped. The aerodynamic instability of pure torsional motion is heavily dependent on the location of the torsion axis and the interblade phase angle.・The computation programs on the bas … More is of the three-dimensional double linearization theory for linear and rotating annular cascades with supersonic axial velocity were developed to predict the unsteady aerodynamic characteristics of cascading blades vibrating under nonzero mean loading. It is found that the single-degree-of-freedom pure bending flutter can occur due to nonzero mean loading. The aerodynamic exciting force is very sensitive to the blade camber on which the steady loading is heavily dependent.・The computation program on the basis of the nonlinear Euler equation to predict the nonlinear steady flow through a two-dimensional cascade with a supersonic leading edge locus was developed. Comparison of the numerical results with those by the linearized theory was conducted. The linearized theory can predict the steady lift force within 10% accuracy at small incidence angles, but the deviation becomes significant as the incidence increases. The main reason of the difference is inaccurate prediction of location of shock wave reflections.・The measurement system including the Mach-Zehnder interferometer and the image processing system have been constructed. The technology of processing interferograms is being developed. Less