... The HH flow associated with young stellar object HL Tau has an exciting history and even until now the origin of some its features is not clear yet. ... Knotty structures of Herbig-Haro jets are common phenomena and knowing the origin of such structures is essential for understanding the processes of jet formation. ... In the flow detected compact knots with high (-150 km/s) and bow shape structures in front of those, with low radial velocities (-50 km/s). ...