Motive steam acceleration

The motive steam accelerates to such a great velocity that it can exceed the speed of sound (that is, exceed sonic velocity). This tremendous increase in velocity of the steam represents a tremendous increase in the kinetic energy of the steam. The source of this kinetic energy is the pressure of the steam. 

The ejector is operated directly by a motive gas or vapor source. Air and steam are probably the two most common of the motive gases. The ejector uses a nozzle to accelerate the motive gas into the suction chamber where the gas to be compressed is admitted at right angles to the motive gas direction. In the suction chamber, also referred to as the mixing chamber, the suction gas is entrained by the motive fluid. The mixture moves into a diffuser where the high velocity gas is gradually decelerated and increased in pressure. 

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