An Experimental Study of the Jet in Cross-Flow in Fully Developed Turbulent Channel-Flow

Abstract

In this study a transient air jet in a fully developed turbulent channel flow has been studied. The main objective has been to see how the behaviour of the jet has been effected by the turbulent channel flow.

The flow in the channel was first investigated through measurements with a Pitot static probe. A jet was then processed and inserted into the channel. Measurements of the resulting flow field were performed with a Pitot rake and a 5-hole Pitot probe. The results of these measurements have been analysed and compared to results from previous studies.

The velocity contours based on the results from the Pitot rake have proven to lack essential information about the jet in cross-flow flow field. The main feature of the flow field of the jet in cross-flow, the counter rotating vortex pair, was for instance not visible in the results collected with the Pitot rake.

The results from the 5-hole Pitot probe showed a much better ability to capture the features of the complex flow field resulting from the jet in cross-flow.

Based on the results from this study, it does not seem that the turbulence have had a great impact on the development jet in cross flow. The development of the jet trajectory fits scaling laws found in previous studies. An increased vertical velocity component in the flow field and a delay in the development of the counter rotating vortex pair were noted as areas where the results from the turbulent channel differ from the results from previous studies.