Velocity characteristics of confined coaxial jets with and without swirl
Abstract
Measured values of the velocity characteristics of turbulent, confined, coaxialjet flows have been obtained, without swirl, for ratios of maximum annulus to pipe velocities of 1.0 and 3.0 and with a swirl number of 0.23 for a velocity ratio of 3.0. They were obtained by a combination of pressure probes, hotwire and laserDoppler anemometry. The results are compared with calculations, based on the solution of finitedifference forms of the steady, NavierStokes equations, and on effectiveviscosity hypothesis. The measurements allow the influence of confinement and swirl to be quantified and show, for example, the increased tendency towards centerline recirculation which results from both. The results with the three types of instrumentation allow a comparison within the corner recirculation region which reveals that serious errors of interpretation of meanvelocity measurements need not arise. The twoequation model, although able to represent the nonswirling flow, is less appropriate to the swirling flow and the reasons are indicated.
 Publication:

American Society of Mechanical Engineers
 Pub Date:
 December 1979
 Bibcode:
 1979asme.meetU....H
 Keywords:

 Coaxial Flow;
 Flow Characteristics;
 Flow Velocity;
 Jet Flow;
 Pipe Flow;
 Turbulent Flow;
 Circulation;
 Finite Difference Theory;
 Flow Distribution;
 Flow Measurement;
 HotWire Anemometers;
 Laser Doppler Velocimeters;
 NavierStokes Equation;
 Pressure Sensors;
 Swirling;
 Fluid Mechanics and Heat Transfer