Experimental Research of Pressure Irregularity Within Exhaust Hood Model for Low-Power Steam Turbine

Vibrational reliability control for turbine blades is the most important requirement of turbomachinery industry. In most cases blades vibrations are caused by aerodynamic forces connected with irregularity of velocity and pressure fields. However, there are practically no data in scientific literature on the problem of impact on a blades vibration condition of irregular pressure inside exhaust hood for steam turbines. The problem of intensity estimates of static pressure irregularity within the entrance section for axial-radial exhaust hood of low power steam turbine is solved. For this purpose exhaust hood model is built and static pressure distribution within computational the entrance section is obtained by numerical simulation. Then, an experimental research of pressure irregularity was carried out using a physical model of exhaust hood. Air was used as a working body at M= 0.17...0.19. The comparison of the obtained results with the computational ones showed that satisfactory quality coincidence is observed only within angle range of 0...180°. An evaluation method of irregularity value was offered. The research showed that pressure irregularity in the axial-radial exhaust hood caused by the inverted stream exists and the evaluation method has been offered.

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