What is rotor dynamic analysis?

Rotordynamics, also known as 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.

What is a centrifugal compressor define briefly?

Centrifugal compressors, also known as dynamic compressors, efficiently converts the energy utilizing a series of stages to compress and cool the air as it continuously flows through the unit.

What is aerodynamic cross coupling?

Cross-coupling in all flying aircraft, including helicopters, is the occurrence of instability in an aircraft due to violent motions on the three axis. It causes the helicopter to drift towards the tail rotor.

What is a supercritical rotor?

There are two types of centrifuges: subcritical and supercritical. A rotor is subcritical when it operates at a rotational frequency less than the lowest flexural resonance frequency and supercritical when operates above it.

What is a rotor critical speed?

Critical speed (nk) is the rotational speed at which acting dynamic forces cause a machine component (e. g. shaft, rotor) to vibrate at its natural frequency (also referred to as intrinsic frequency, fi) and can even result in resonant vibrations throughout the entire machine and pump set.

What are the two types of centrifugal compressor?

Centrifugal compressor can be made into different configuration to suit specific services. the foremost being either a single stage centrifugal compressor or a multistage centrifugal compressor.

What is centrifugal compressor and what are its advantages?

Advantages of centrifugal compressor Low weight, easy to design and manufacture. Suitable for continuous compressed air supply, such as cooling unit. The oil free in nature. They have fewer rubbing parts. Generating a higher pressure ratio per stage as compared to axial flow compressor.

What is cross coupling stiffness?

Cross-coupled stiffness (CCS) can be generated from fluid pressure forces in internal machine components such as gas/liquid seals, hydrodynamic bearings, axial flow turbomachinery stages, and centrifugal impellers. These CCS forces are purely distortive to the orbit and are not de-stabilizing.

What is the jeffcott rotor model?

Jeffcott rotor is the simplest model to study the flexural behaviour of rotor mass system. In this model the rotor was assumed to be massless and a point mass is attached to the rotor at some distance from the centre called eccentricity. The rotor is modelled by considering both damping and undamped condition.

Why are rotors important in a centrifugal compressor?

Rotordynamics play a very important role for large LNG centrifugal compressors where the rotational speeds may be low but bearing spans can be very large (up to 5850 mm). In general these large rotors are quite rigid and have good separation margins.

What are the two types of rotordynamic analysis?

Rotordynamic Analyses There are two types of rotordynamic analysis commonly performed on compressor drive trains: lateral and torsional. Torsional analysis evaluates the twisting interaction between rotors and couplings. A lateral analysis evaluates the rotor vibration in a compressor or train of equipment.

What’s the difference between a centrifugal and axial compressor?

That is the fundamental difference between the axial compressor’s rotor and the centrifugal (or radial) compres- sor’s impeller — the axial rotor discharges flow in the axial direction while the centrifugal impeller discharges in a radial direction.

How are the bearings used in a centrifugal compressor?

Centrifugal compressors are equipped with two radial (journal) bearings to support the rotor weight and position the rotor concentrically within the stationary elements of the compressor. One thrust bearing also is used to ensure that the compressor rotor is maintained in its desired axial position.