Experiments on Coaxial Heated Water Discharges

The paper describes an experimental investigation in which heated water was discharged coaxially into rectangular open channel flow from a slot placed at the channel center. Discharge and channel velocity were the same, and discharges with excess temperatures of 9 °C and 20 °C were studied. The temperature distribution in the near field was measured in detail with thermistors, and the surface motion was recorded by photographing surface floats. The photographs show how the warm water spreads at the surface and that it forms a straight front whose angle with the center line increases with increasing density difference. Isotherm pictures are given for various cross-sections down to 16 water depths from the discharge, and these show the rise to and the spreading at the surface of the warm water, the formation of warm-water pools off the centre line at the surface, the inward motion of cold channel water near the bottom, and the eventual detachment of the warm water from the bottom.