Influence of Seals with Frequency Dependent Characteristics on the Rotordynamic Behaviour of High Pressure Compressors

The economic development of oil fields in increasingly difficult environments requires unconventional technical solutions for turbo compressors which are installed for the re-injection of the gas into the oil reservoir. In this paper a compressor rotor designed for a discharge pressure of 1000 bar with a honeycomb seal on the balance piston is presented and compared to the behaviour with a labyrinth seal. The force characteristics of the seals have been measured in a special test stand designed for this type of measurement. It is shown, that the traditional description of the forces with constant stiffness and damping coefficients can no longer be applied in case of a honeycomb seal. A new approach with the description of the forces by means of transfer functions is described. The rotordynamic stability of the compressor is analysed by modelling the seal transfer function in a similar way as it is done for a “magnetic bearing”. 1