Compression and Surge

Centrifugal Compression and Surge Mechanically, what is surge  

When a spinning wheel (with a wheel tip velocity of perhaps 600 miles an hour) touches a stationary element, the compressor internals are wrecked. Pieces of the wheel have been know to tear through the 

The gas enters the compressor s rotor through the large wheel shown in Fig. 28.2. The purpose of this wheel is to increase the velocity or kinetic energy of the gas. After the high-velocity gas escapes from the vanes in the wheel, the gas enters the stationary elements fixed to the inner wall of the compressor case. This is called the stator. Inside the stator the velocity or kinetic energy of the gas is converted to polytropic feet of head, or potential energy. 

Brave reader, do not be afraid of the term polytropic feet of head. It really has the same simple meaning as described in Chap. 23, except the term polytropic feet of head means feet of head for a compressible fluid. 

To convert from poly tropic feet of head to AP, which is really what us process people are interested in, we use the following very rough approximation  

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