| 摘要 |
A rotary gas-handling machine and rotor therefor in which the number of puffs of gas affecting the rotor so as to tend to excite vibrations therein on each revolution will be such that for the designed speed of operation of the rotor the resulting frequency of excitation puffs will be different from each of the resonant frequencies of the rotor, such as the resonant frequency for "saddle" vibration, blade vibration, rotational and outer edge vibration of the shroud, etc. The excitation frequency is also made to differ from one-half of each of the resonant frequencies. In the case of such a machine in the form of a turbine the number of excitation puffs per revolution is determined by the number of circumferentially spaced nozzles carried by the housing to direct the gas against the rotor, while in the case of a compressor rotor the number of excitation puffs per revolution is determined by the number of blades. The blades and the shroud are preferably made thicker adjacent their inner extremities both to deter vibration by inherent stiffness of such thicker members and to change their natural frequencies by the mass of the thickened members. The same sort of structure makes the shroud more resistant to vibration by stiffening an important component of the "spring" of the resonant mode while strengthening it against shear. Another expedient is to cause the blades to protrude from the wheel outwardly past the plane of the eye of the shroud and be joined to the hub out beyond such plane so as to provide bracing for both the shroud and the disk of the rotor against axial vibration.
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