Abstract: This article investigates through experiments the flow characteristics of plane jets from sharp-edged orifice-plate, beveled-edge and radially contoured nozzle. The first two configurations exhibit saddle-backed velocity profiles while the third shows a top-hat. A vena contracta is found for the jet emanating from orifice at x/h » 3 while the contoured case displays a potential core extending to the range x/h = 5. A spurt in jet pressure on the centerline supports vena contracta for the orifice-jet. Momentum thicknesses and integral length scales elongate linearly with x although the growth of the shear-layer and large-scale eddies for the orifice are greater than the contoured case. The near-field spectrum exhibits higher frequency of the primary eddies that concur with enhanced turbulence intensity. Importantly, highly “turbulent” state of the orifice-jet prevails in the far-field where the spectra confirm more energetic secondary eddies associated with greater flapping amplitude of the orifice-jet.
Abstract: Subsonic wind tunnel experiments were conducted to
study the effect of tripped boundary layer on the pressure distribution
in the contraction region of the tunnel. Measurements were
performed by installing trip strip at two different positions in the
concave portion of the contraction. The results show that installation
of the trip strips, have significant effects on both turbulence and
pressure distribution. The reduction in the free stream turbulence and
reduction of the wall static pressure distribution deferred signified
with the location of the trip strip.