In this paper, wall jets discharged from round nozzles (D = 43 mm [1.7 in.], 76 mm [3 in.], and 152 mm [6 in.]) were tested in a room (4.2 m x 3.6 m x 2.7 m [13.8 ft x 11.8 ft x 8.9 ft]) and measurement results show the following.

• In the case of big nozzles (D = 76 mm [3 in.] and 152 mm [6 in.]), the maximum velocity decay coefficient K-values of a wall jet can always be estimated by multiplying with those of a free jet with the same exit area. However, for the small size nozzles (D = 43 mm [1.7 in.]), K-values become lower.
• The end maximum velocity of zone 3 could be proportional to outlet velocity, and gradient can be related to room size. A smaller test room gives a higher value.