Abstract:
Different characteristics and performance parameters for the exhaust of nozzle are analyzed
both experimentally and analytically to observe the behavior of the free jet and swirling jet
discharge into a quiescent environment. Swirl plays a significant role by escalating the
dispersion of free turbulent jets. Swirling jets represent one of a few basic flow pattern that has
a great practical significance in practical field. It allow the fundamental study of complex but
generic dynamical processes and their interactions. They feature prominently in a variety of
propulsion systems. In combustion application, their ability to create reverse flow regions near
the jet nozzle has been exploited for the purpose of swirl-stabilizing the flame. Swirling jets
have many other possible industrial application also. The objectives of the present research is
a comparative study between the plane circular jet and swirling jet. It was carried out to assess
the effect of initial condition such as Reynolds number and pitch of swirls generator on swirling
jets. A circular nozzle of 60 mm diameter was used for the whole experiment. Velocity profiles
were attained for two initial condition Re = 8.4e4 & Re = 1.27e5. In the measurement system
a 3-hole yaw-meter of United Sensor Ltd (USA) along with sensitive incline tube manometers
were used for the measurement of axial velocity and flow direction. The yaw-meter was located
in different position of the jet flow by a precision height gause which was mounted on a
precision traversing mechanism. The velocity profiles for six conditions (a) Free jet, (b) Free
jet with extension tube, (c) Swirling jet using 5 deg. (d) Swirling jet using 15 deg.. (e) Swirling
jet using 15 deg. were evaluated in this study. It was found that the Reynolds number had little
effect on the velocity profile of any of the described six cases. A top hat shaped velocity profile
was observed near the nozzle exit of plane jet, as the flow develops the shape changes and
become more like inverted U shape. The velocity profile for the free jet with extension tube is
quite similar to the free jet but the profiles were smoother. Introduction of swirl with the jet
increases the mixing of jet with surrounding air. For swirling jet the velocity deterioration is
quicker than free jet. The potential core of free jet was present up-to axial distance of X/D =
3.5.
