A rotating assembly adapted for use in turbines and pumps is provided. The rotating assembly includes a shroud that rotates around a central axis and a disk seated in a recess in the shroud so that the disk rotates with the shroud, the disk being oriented perpendicular to the central axis. The rotating assembly also includes a stationary element in which at least one surface of the disk contacts a fluid so that when the fluid flows under pressure, the surface of the disk resists the generation of drag between the surface and the stationary element of the rotating assembly. A shroud is provided that includes a circular recess with a cavity on an outer perimeter extending away from the fixed assembly. A method of manufacturing a rotating assembly is provided.

A method for pressure and temperature control of fluid in a series of cryogenic compressors. An actual speed for each compressor and an actual inlet pressure and actual inlet temperature at entry are determined. The maximum speed for each compressor and a desired inlet pressure for the first compressor is provided. A speed index for each compressor is determined from the maximum speed and actual speed of each compressor. A proportional value is determined from the deviation of the actual and desired inlet pressure. A priority value is determined from the smaller of the proportional value and the smallest speed index. A desired inlet temperature for the first compressor and a desired speed for each compressor are determined from the priority value. The actual inlet temperature is adjusted to the determined desired inlet temperature and the actual speed for each compressor is adjusted to the determined desired speed.

A method for controlling speeds of compressors arranged in series for compressing a fluid. The desired inlet pressure is predefined and the actual inlet pressure is detected. The actual discharge pressure of the fluid is recorded and the actual total pressure ratio is recorded. A proportional integral value is determined from the deviation of the actual inlet pressure from the desired inlet pressure and a capacity factor is determined from the proportional integral value and the actual total pressure ratio. A model total pressure ratio is determined from the actual total pressure ratio and the capacity factor. A reduced desired speed for each compressor is determined as a function value of the control function associated with the respective compressor. The control function assigns a reduced desired speed to each value pair of capacity factor and model total pressure ratio and is used to adjust the speed of each compressor.

A rotor assembly is provided and includes a two-piece rotor impeller and a rotor shaft. The two-piece rotor impeller includes a blade section and a forward section, which is connected to the blade section. The rotor shaft includes an aft section at which the rotor shaft terminates. The aft section is directly attached to the forward section of the rotor impeller. The blade section includes a converging blade configured to converge to a point with a minimized internal diameter (ID).

A rotor assembly is provided and includes a two-piece rotor impeller and a rotor shaft. The two-piece rotor impeller includes a blade section and a forward section, which is connected to the blade section. The rotor shaft includes an aft section at which the rotor shaft terminates. The aft section is directly attached to the forward section of the rotor impeller. The blade section includes a converging blade configured to converge to a point with a minimized internal diameter (ID).