抄録
he influence of dynamic fluid reaction forces and moments of a long annular seal on the stability of fluid machinery was investigated. The stability analysis was carried out by using a submerged motor pump in a circulation boiler, in order to explain the effect of the long seal. In the stability analysis, the individual contributions of the fluid forces and moments due to rotor conical and cylindrical whirl movements were evaluated according to logarithmic decrements. As a result, the individual contributions depend on the mode shapes of the vibration. Fluid forces acting on the long seal due to conical and cylindrical whirl movements should not be ignored because they play an important role in the stability.
