Rootes blower rotary compressor

Dry Vacuum Pumps (DVPs) These use the operating principles of rotary-lobe roots blowers, claw compressors or screw compressors, and hence require electrical power. They run dry and hence at very high temperature due to the heat of compression. Usually,... 

Many users consider rotary compressors, such as the Rootes -type blower, as turbomachines because their behavior in terms of the rotor dynamics is very close to centrifugal and axial flow machinery. Unlike the reciprocating machines, the rotary machines do not have a very high vibration problem but, hke the reciprocating machines, they are positive-displacement machines. 

Figure 7.19. Some rotary positive displacement compressors (a) A two-lobe blower, (b) Performance of a two-lobe blower Roots-Connersville Co.), (c) A screw pump with one power and two idle rotors (Kristal and Annett, 1940). (d) Performance ot 3 5 screw pump handling oils at 1150 rpm against 325 psig Kristal mi Annett, 1940). (e) Rinciple of Ihe liquid ring seM compressor (Nash Et meemg Co.), (f) A shding vane Mower (Beach-Russ Co.).

---