This work focuses on the interconnection of internal flow field and liquid sheet stability of slit nozzles. The main issue was to supplement the existing experimental data with particle image velocimetry (PIV) experiments on the inner flow field of three different nozzle designs and visualization of the sheet modulation and breakup at Reynolds numbers about Re=19000. The main difference of these nozzles was the channel length. Like in former investigations, the dominating influence of the internal flow conditions on the film stability became obvious. The results support the conclusion that a certain amount of turbulence stabilizes the liquid film, as stated by [2]. The use of a double pulse technique for backlit photography of the free liquid film gave the opportunity to determine the velocity of the surface deformations near the nozzle exit. This in combination with the knowledge about the internal flow field allowed drawing conclusions about the energy transfer between core flow and free liquid surface at the nozzle exit. It is suggested that this energy transfer plays an important roll in the promotion of disturbances and surface deformation and therefore has an essential influence on the liquid sheet stability. 德國LaVision PIV/PLIF粒子成像測速場儀 自適應(yīng)粒子成像測速場儀（PIV）