In the present work, computational fluid dynamics (CFD) studies on single phase turbulent confined jets were carried out. The CFD model was validated by comparison with a number of parameters available from the previous literature. An attempt is made to study the jet expansion and hydrodynamics in presence of confinement. This has been studied in two ways: (i) effect of enclosure size and (ii) effect of presence of draft tube. The effect of enclosure size was investigated over a wide range and compared with the previous literature. It was observed that with an increase in the draft tube diameter, the entrainment rate of the surrounding fluid into the draft tube increases while the average turbulent kinetic energy in the jet flow in draft tube decreases. Thus the size of the draft tube plays an important role in determining the level of entrainment and the extent of mixing between the jet fluid and the surrounding fluid. (c) 2007 Elsevier B.V. All rights reserved.