76. Flow Pattern Generated by a Radial Jet

The article is focused on a radial jet investigation. The radial jet is one of the most important features of a rein­ forced exhaust system known as the Aaberg exhaust hood. In order to describe a radial jet flow pattern, measurements of radial jet characteristics, such as velocity decay, spreading rate and turbulence intensity profiles across the jet, are needed. An experimental set­up has been built up. It allows the measurements to be taken under various geometrical (jet width and orifice diameter) and initial conditions (turbulence intensity, air speed, and temperature at the inlet). The set­up consists of an air terminal that creates the radial jet, a ductwork with a fan unit and a heat exchanger. The basic dimensions of the air terminal are 200 mm in diameter and the width of the terminal nozzle is 4 mm; both of them are adjustable. The flow rate can be varied from 50 to 1200 m3/h. Data acquisition system is based on a computer and it enables the storage and evaluation of data from all measuring devices and sensors in real time. For the basic ar­ rangement, a set of measurements were undertaken and results of that were compared with available literature. The ra­ dial jet was also simulated numerically by means of a commercial CFD code with the aim of using this tool for further development and optimisation of radial jet reinforced exhaust system. Comparison of the results, both experimental and numerical, with available expressions and data for velocity decay shows as much as 30 % discrepancy.