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Handbook of Turbomachinery Second Edition Revised - Ventech!

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Figure 5 Schematic <strong>of</strong> the ‘‘air-injection supercharging’’ system tested by General<br />

Motors in the late 1950s.<br />

took at least a half hour to bring the tanks up to full charge using the<br />

engine-driven compressors. The 3,000-psi air bottles could also become<br />

‘‘bombs’’ in a crash.<br />

SUPERCHARGERS<br />

There are basically two distinct categories, classified according to<br />

compressor type, <strong>of</strong> mechanically driven superchargers that have been<br />

used with production gasoline engines. First there are the positivedisplacement<br />

types, which are characterized by the Roots, rotary piston,<br />

or vane-type superchargers. During each revolution, the positivedisplacement<br />

supercharger pushes the air charge into a zone <strong>of</strong> higher<br />

pressure.<br />

The second type is a dynamic or kinetic supercharger that uses a<br />

mechanically drive radial- or axial-flow compressor. These turbomachines<br />

convert the mechanical energy into kinetic energy by accelerating the air<br />

charge. This increased kinetic energy is converted to increased pressure by<br />

using <strong>of</strong> a diffuser. Incidentally, the turbocharger is a kinetic turbomachine<br />

except the drive energy comes from an exhaust-driven turbine rather than<br />

being mechanically driven by the engine crankshaft via belt or gears. Indeed,<br />

it is also called a turbosupercharger.<br />

Copyright © 2003 Marcel Dekker, Inc.

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