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Rotor solidity is a dimensionless quantity used in design and analysis of rotorcraft, propellers and wind turbines.Rotor solidity is a function of the aspect ratio and number of blades in the rotor and is widely used as a parameter for ensuring geometric similarity in rotorcraft experiments.
Such a chart can be used in turbine design. Experimentally measured vibration response spectrum as a function of the shaft's rotation speed (waterfall plot), the peak locations for each slice usually corresponding to the eigenfrequencies.
Rotordynamics (or rotor dynamics) is a specialized branch of applied mechanics concerned with the behavior and diagnosis of rotating structures. It is commonly used to analyze the behavior of structures ranging from jet engines and steam turbines to auto engines and computer disk storage .
A static balance (sometimes called a force balance [2] [3]) occurs when the inertial axis of a rotating mass is displaced from and parallel to the axis of rotation.Static unbalances can occur more frequently in disk-shaped rotors because the thin geometric profile of the disk allows for an uneven distribution of mass with an inertial axis that is nearly parallel to the axis of rotation.
Phase lag may vary depending on rotor tilt rate, ratio of aerodynamic damping to blade inertial forces (Lock number), offset of flapping hinge from axis of rotation (e/R ratio), and coupling of blade flap, drag, and feather motions, and often results in cross-coupling between the aircraft control axes. Phase lag is a property of all rotating ...
These four readings are sufficient to define the size and position of a final mass to achieve good balance. Ref 4 For production balancing, the phase of dynamic vibration is observed with its amplitude. This allows one-shot dynamic balance to be achieved with a single spin, by adding a mass of internally calculated size in a calculated position.
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When it does occur, recovery is often possible if action is taken quickly. If sufficient rotor RPM exists, immediate takeoff can restore rotor balance by allowing the airframe to move and help dampen the oscillation freely. [1] Complete shutdown may be sufficient if rotor RPM is very low during a ground resonance incident.