In axial-flow turbomachines considerable dynamic blade loads and noise production occur as a result of the unsteady blade row interaction between rotor and stator blades. This paper presents results of midspan measurements of the dynamic pressure distribution on the stator blade surface (fixed number of blades) for various rotor-blade numbers and various axial clearances between rotor and stator. For this purpose, one stator blade had been provided with eleven semiconductor pressure transducers in the midspan section. Simultaneously, the sound pressure level was measured at two axial distances downstream of the stator by four condensator microphones distributed along the circumference in each of the two sections and mounted flush with the wall surface. The wake-flow distribution downstream of the rotor could be obtained by a rotating three-hole pressure probe. The results of the corresponding dynamic pressure-measurements and noise measurements are discussed and compared with results from theory.

This paper contains the results of the measurements of fluctuating pressures on the mid-span profile surfaces of both rotor and stator blades for several points of operation. By the aid of rotating probes behind the rotor, the shapes of the rotor wakes were measured, too. All the measurements have been performed twice, at first with guide vanes in front of the rotor, and afterwards without the latter. The results of the measurements are evaluated with respect to the parameters involved, like Strouhal-number, reduced frequency, and circumferential Mach number. The flow analysis is done for various wake-fields behind the rotor correspondent to different operation points. Emphasis is given to the establishment of correlations for the blade-row interaction and to the comparison of the measured pressure distributions with computed results according to well-known theoretical approaches.