PRESSURE PULSATIONS IN A DRUM EXCITED BY A CENTRIFUGAL COMPRESSOR CONNECTED TO A PIPING SYSTEM

The characteristics of the pressure pulsations in a drum connected to a piping system excited by a centrifugal compressor or a blower operated at blade-passing frequencies were investigated. In this study, the equivalent resistance of a compressor and that of a piping system were introduced and linked to the three dimensional calculation model, so that the non-linear damping proportional to velocity squared in the system is properly incorporated. The experiment was performed in order to validate the proposed simulation model. As a result, the three dimensional pressure response in the drum as well as the pipe can be well evaluated by this model. Furthermore, the effect of the acoustic dynamic absorber on the pressure pulsations in the pipe and drum is evaluated. When the resonant frequency of the pipe coincides with that of the drum, two peaks appear in the frequency response curve around the resonant frequency of the pipe, because the drum acts as an acoustic dynamic absorber. It is shown that the maximum pressure amplitude in the drum is obtained when the resonant frequency of the pipe is slightly shifted from the resonant frequency of the drum under the small damping conditions. The effect of the damping in the drum and the mode shape of the drum on the maximum pressure amplitude in the drum is discussed in detail.