Impinging jet and combined slot nozzle

The paper is an experimental study olf a special kind of slot nozzle. The f low field with recirculation area results from a structure built in the noz zle (the so called combined slot nozzle). As the nozzle to wall distance ch anges, quantitative changes of the flow field occur. They can be seen in th e development of the wall pressure as well as in the development of the mas s transfer coefficient. Two different sorts of this development have been o bserved, corresponding to two different states of the flow field. The chang e of one into the other is very rapid and hysteretic in character.