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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.
If the object is disk-like, weights may be attached near the rim to reduce the sensed vibration. This is called one-plane dynamic balancing. If the object is cylinder or rod-like, it may be preferable to execute two-plane balancing, which holds one end's spin axis steady, while the other end's vibration is reduced.
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 .
The whirling frequency of a symmetric cross section of a given length between two points is given by: = where: E = Young's modulus, I = second moment of area, m = mass of the shaft, L = length of the shaft between points.
Moreover, at such high speeds the centrifugal forces are immense, and can damage the structure. Hence, compounding is needed. The high velocity steam just strikes on a single ring of rotor that causes wastage of steam ranging 10% to 12%. To overcome the wastage of steam, compounding of steam turbines are used.
For a given weight, a helicopter with shorter rotors will have higher disk loading, and will require more engine power to hover. A low disk loading improves autorotation performance in rotorcraft. [5] [6] Typically, an autogyro (or gyroplane) has a lower rotor disk loading than a helicopter, which provides a slower rate of descent in ...
Analytical Campbell Diagram for a Simple Rotor. A Campbell diagram plot represents a system's response spectrum as a function of its oscillation regime. It is named for Wilfred Campbell, who introduced the concept. [1] [2] It is also called an interference diagram. [3]
There are three general designs. The earliest, and by far, least common design today, is the fully rigid rotor system; the blades are rigidly fixed to the rotor hub but made of a flexible material that allows some degree of flap. Semi-rigid rotor systems have a horizontal hinge at the base of the blades that allow flap as they rotate. By ...