Normally, the ejector design can be classified into two types according to the
position of the nozzle. The ejector, which has the nozzle with its exit plane located
within the suction chamber in front of the constant-are section, as described by
Keenan’s theory, the static pressure was assumed to be constant through the mixing
process. Therefore, this kind of ejector is known as a ‘constant-pressure mixing
ejector’ (Fig. 3a). For the nozzle with its exit located within the constant-area section,
the ejector is called a ‘constant-area mixing ejector’ (Fig. 3b) [20,41,42]. At
the beginning, it was thought that a constant-area mixing ejector could entrain a
higher amount of secondary flow than a constant-pressure mixing ejector [43].
Both types of ejector have been extensively tested experimentally over the intervening
years. It was found that the constant-pressure mixing ejector had a better performance than the constant-area one. Therefore, almost all current study has been
focused on the constant-pressure mixing ejector.