AN INVESTIGATION TURBULENCE MODEL OF STANDARD k- TO GET OPTIMUM PARAMETERS OF TURBULENCE CONSTANTS (cµ, c1, AND c2) OF COMPRESSIBLE FLUID DYNAMICS IN A CONFINED JET

This research aims to find the optimal standard k- turbulence model constants (cµ, c1, and c2) for
better predicting compressible fluid dynamics in an air jet ejector. The turbulence field in a jet flow plays
an important role in influencing the performance of the momentum transfer process at a shear layer in
nozzle application for momentum source and mixing process. In this research, some activities have been
done before analyzing and optimizing the turbulence model constants, including preliminary turbulence
modeling study for compressible flow in the air-jet ejector, verification, and validation with primary
experimental data as well as by other secondary data. The preliminary studies in turbulence modeling
presented that the turbulence modeling of a 3mm air jet-ejector resulted in a similar trend of the relation
between entrainment ratio and motive fluid pressure. The results showed that the sensitive parameters in
the standard k-
model dissipation and diffusion terms, cµ, c1, and c2, strongly affected the optimum
value of turbulence kinetic energy (k) and dissipation rate (), compared to the reference model. Better k
and  could be obtained by changing the c2 into positively proportional, but the cµ and c1 must be
changed with opposite proportionality. It was found that the optimum standard k- model constants in the
case of air-jet ejector with 3 mm nozzle diameter for cµ, c1, and c2 are 0.05, 1.48, and 1.88, respectively,
with the error values for k being -8.88% and  being -17.44%.