Abstract: The article deals with experimental and numerical
investigation of axi-symmetric subsonic air to air ejector with
diffuser adapted for boundary layer suction. The diffuser, which is
placed behind the mixing chamber of the ejector, has high divergence
angle and therefore low efficiency. To increase the efficiency, the
diffuser is equipped with slot enabling boundary layer suction. The
effect of boundary layer suction on flow in ejector, static pressure
distribution on the mixing chamber wall and characteristic were
measured and studied numerically. Both diffuser and ejector
efficiency were evaluated. The diffuser efficiency was increased,
however, the efficiency of ejector itself remained low.
Abstract: The article deals with pneumatic and hot wire
anemometry measurement on subsonic axi-symmetric air ejector.
Performances of the ejector with and without pulsations of primary
flow are compared, measuring of characteristic pressures and mass
flow rates are performed and ejector efficiency is evaluated. The
pulsations of primary flow are produced by a synthetic jet generator,
which is placed in the supply line of the primary flow just in front of
the primary nozzle. The aim of the pulsation is to intensify the
mixing process. In the article we present: Pressure measuring of
pulsation on the mixing chamber wall, behind the mixing chamber
and behind the diffuser measured by fast pressure transducers and
results of hot wire anemometry measurement. It was found out that
using of primary flow pulsations yields higher back pressure behind
the ejector and higher efficiency. The processes in this ejector and
influences of primary flow pulsations on the mixing processes are
described.
Abstract: The article deals with numerical investigation of axisymmetric
subsonic air to air ejector. An analysis of flow and mixing
processes in cylindrical mixing chamber are made. Several modes
with different velocity and ejection ratio are presented. The mixing
processes are described and differences between flow in the initial
region of mixing and the main region of mixing are described. The
lengths of both regions are evaluated. Transition point and point
where the mixing processes are finished are identified. It was found
that the length of the initial region of mixing is strongly dependent on
the velocity ratio, while the length of the main region of mixing is
dependent on velocity ratio only slightly.
Abstract: In this study, an optimization of supersonic air-to-air ejector is carried out by a recently developed single-objective genetic algorithm based on adaption of sequence of individuals. Adaptation of sequence is based on Shape-based distance of individuals and embedded micro-genetic algorithm. The optimal sequence found defines the succession of CFD-aimed objective calculation within each generation of regular micro-genetic algorithm. A spring-based deformation mutates the computational grid starting the initial individualvia adapted population in the optimized sequence. Selection of a generation initial individual is knowledge-based. A direct comparison of the newly defined and standard micro-genetic algorithm is carried out for supersonic air-to-air ejector. The only objective is to minimize the loose of total stagnation pressure in the ejector. The result is that sequence-adopted micro-genetic algorithm can provide comparative results to standard algorithm but in significantly lower number of overall CFD iteration steps.