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When an element of mass is offset from the axis of rotation, centrifugal force will tend to pull the mass outward. The elastic properties of the shaft will act to restore the “straightness”. If the frequency of rotation is equal to one of the resonant frequencies of the shaft, whirling will occur. In order to save the machine from failure ...
Alternatively the map of a similar compressor can be suitably scaled. This article is an overview of compressor maps and their different applications and also has detailed explanations of maps for a fan and intermediate and high-pressure compressors from a three-shaft aero-engine as specific examples.
Stiffness of the shaft and its support; Total mass of shaft and attached parts; Unbalance of the mass with respect to the axis of rotation; The amount of damping in the system; In general, it is necessary to calculate the critical speed of a rotating shaft, such as a fan shaft, in order to avoid issues with noise and vibration.
Rotating shaft unbalanced by two identical attached weights, which causes a counterclockwise centrifugal couple Cd that must be resisted by a clockwise couple Fℓ = Cd exerted by the bearings. The figure is drawn from the viewpoint of a frame rotating with the shaft, hence the centrifugal forces.
The following stresses are induced in the shafts. Shear stresses due to the transmission of torque (due to torsional load). Bending stresses (tensile or compressive) due to the forces acting upon the machine elements like gears and pulleys as well as the self weight of the shaft. Stresses due to combined torsional and bending loads.
Calculation of the steam turbine shaft radius for a turboset: Assumptions: Power carried by the shaft is 1000 MW; this is typical for a large nuclear power plant. Yield stress of the steel used to make the shaft (τ yield) is: 250 × 10 6 N/m 2. Electricity has a frequency of 50 Hz; this is the typical frequency in Europe.
Having a constant diameter, measured at varying angles around the shape, is often considered to be a simple measurement of roundness.This is misleading. [3]Although constant diameter is a necessary condition for roundness, it is not a sufficient condition for roundness: shapes exist that have constant diameter but are far from round.
This is done by either bolting the shafts together or by applying spring pressure from an external housing. This lack of backlash also reduces wear due to fretting. The coupling is defined by the groove count, the outer diameter of the cylindrical feature, the bottom angle of the grooves (to the axis of the cylindrical feature), and their depth.