The effects of nozzle angle and distance between the two nozzles on turbulent dual jet flow pattern were experimentally investigated. This experimental results can be applied to the polymer melt spinning process in which air is the jet medium.
In this study the measurement of characteristics of the dual jet flow was carried out within the limits of x/a ≤ 40 and the angles between the center line of nozzle exit and jet center line were 30℃, 45℃ and 60℃ respectively.
Mean velocity, turbulent velocity components and Reynolds shear stress were measured by a linearized two-channel constant temperature hot wire anemometer. Turbulent intensity distributions, increasing rates of the jet width and momentum flux distributions were calculated with these measured experimental data.
Sub-atmospheric region, which is one of the most remarkable characteristics of dual jet flow, was ascertained by these measurements.
The characteristics of dual jet flow were much influenced by the changes of nozzle angle or distance between two nozzles. As the nozzle angle increased, the lateral mean velocity distributions more deviated from the Goertler's theoretical solution. When nozzle angle was 30℃ or 45℃, the width of combined jet spread linearly in the downstream direction, but in case of nozzle angle was 60℃, there was a change of increasing rate of jet width. Mean momentum fluxes in the downstream direction are not conserved, and when nozzle angle was 60℃, mean momentum fluxes were small as compared with those of 30℃ and 45℃.