From the Mollier’s chart shown in Fig. 2, it can be seen that the normal shock, which creates a major compression effect, causes loss in total pressure of the mixed
stream. If the mixed stream is brought to stagnation state isentropically (without a normal shock), the exhaust pressure will be as high as P04. This can be considered as an ideal ejector, which can be considered as an isentropic compressor driven by an isentropic turbine as shown in Fig. 4a. It must be noted that this model is not a reversible system even if the loss due to the shock is eliminated. Another loss caused by the mixing of two fluid streams (primary and secondary flows) remains. Not only the shear mixing, but the shear force was also introduced to the flowing process by the shear stress layer. These two factors were considered as the cause of entropy generation, and hence, the irreversibility of an ejector. A reversible ejector model which eliminates all losses is shows in Fig. 4b, both isentropic turbine compressor discharge at the same entropy and back pressure. The idea of designing an ejector with minimum losses from normal shock was proposed and named ‘the Constant Rate of Momentum Change method, (CRMC)’, by Eames . The ejector was designed so that the static pressure of the mixed flows was allowed to gradually increase from entry to exit while passing through the ejector. Without the shock, therefore, there is no stagnation pressure loss. It was claimed that the pressure lift ratio of the CRMC ejector was increased while the entrainment ratio remained unchanged. In the same manner, the losses created by normal shock were minimized in the experiment of Chunnanond and Aphornratana .