Models of ejectors
Note :
An ejector or injector receives as input two fluids normally gaseous but which may also be liquid or two-phase:
the high pressure fluid called primary fluid or motive;
the low pressure fluid, called secondary fluid or aspirated.
The primary fluid is accelerated in a converging-diverging nozzle, creating a pressure drop in the mixing chamber, which has the effect of drawing the secondary fluid. The two fluids are then mixed and a shock wave may take place in the following zone. This results in an increase in pressure of the mixture and reduction of its velocity which becomes subsonic. The diffuser then converts the residual velocity into increased pressure.
The ejector thus achieves a compression of the secondary fluid at the expense of a decrease in enthalpy of the primary fluid.
Models of ejectors
Three external classes model ejectors: FluidEjector, GasEjector and IdealGasEjector.
The first is for condensable vapors (refrigerants, steam...). It has been almost validated against the work of Li and Groll referenced in the documentation. This class combines equations of real fluids and ideal gas, which is not entirely satisfactory, but seems about justified.
The second is for the case where the same ideal gas is used as motive and secondary fluid. It was developed in parallel with the previous, the model being similar except for the fluid properties, but was only partially validated
The third is a generalization of the second in case the motive and secondary fluids are two different ideal gases. Their mixture is then recalculated. It is also only partially validated.
You will find below the various documents defining the external class:
Presentation of the model / Instructions for use of class FluidEjector
Presentation of the model / Instructions for use of class IdealGasEjector
Java code of the external classes
extUser.zip or extUser2.zip file containing the three classes
CRC_pa_3
