Experimental work was carried out by Electricité de France at Chatou on two-phase critical flow in long nozzles. The experiments were carried out on two steam-water facilities: one with steady-state conditions and the second with transient conditions. The ranges of the various parameters studied are as follows:

  1. critical pressure: from 1.7 to 6.1 MPa
  2. mass flux: from 17 000 to 50 000 kg/m2·s
  3. nozzle diameter: from 12 to 50 mm.
A comparison with theoretical calculations made with a computer code that takes thermal nonequilibrium in account was made. These are precalculations because the code had been fitted to low-pressure data only. The error in the flow rate prediction lies between +5 and −5% for most of the points and between +5 and −27% for all experimental points.