Supersonic steam ejectors are simple devices which can be used to compress a low pressure flow by a pressurized motive flow. “Compression ratio” and “entrainment ratio” are two major characteristics of the ejectors. One of the current challenging issues in ejector design is the correct size selection for different dimensions of ejectors to achieve the maximum entraining capability at a given compression ratio. The conventional design methods are based on varying shape parameters such as lengths, angles and diameters and pick a particular geometry which yields the best performance under a given boundary conditions.
In the current study, a new method of size selection for different geometrical parameters of ejectors will be introduced. The basis of this method is to define a non-dimensional volume in terms of ejector dimensions. The effect of varying this parameter on the characteristics of ejectors has been studied numerically via a CFD method. The numerical simulation has been performed on more than 400 ejector models with different geometries according to the finite-volume steady-state method. Steam was taken as the working fluid and it was assumed a real gas with a nonlinear relationship between pressure and density. The numerical results verified with experimental measurements obtained from a pilot model of steam ejector. This method enables us to develop the practical characteristic curves based on non-dimensional parameters which further leading to achieve an optimized size selection for design purposes.