CPC F02C 7/36 (2013.01) [F02C 7/06 (2013.01); F05D 2220/32 (2013.01); F05D 2240/50 (2013.01); F05D 2240/60 (2013.01); F05D 2260/40 (2013.01)] | 20 Claims |
1. A turbomachine engine comprising:
a fan section having a fan shaft;
a core engine including one or more compressor sections, one or more turbine sections that includes a power turbine, and a combustion chamber in flow communication with the compressor sections and turbine sections;
a low-speed shaft coupled to the power turbine and having a midshaft that extends from a forward bearing to an aft bearing, the low-speed shaft being characterized by a midshaft rating (MSR) between two hundred (ft/sec)1/2 and three hundred (ft/sec)1/2, wherein the low-speed shaft has a redline speed between fifty and two hundred fifty feet per second (ft/sec), and the turbomachine engine is configured to operate up to the redline speed without passing through a critical speed associated with a first-order bending mode of the low-speed shaft; and
a gearbox assembly that couples the fan shaft to the low-speed shaft, the gearbox assembly characterized by a gearbox assembly mode that is less than 95% of a midshaft mode of the midshaft or greater than 105% of the midshaft mode.
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