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Fig. 3.15 Pipe flow
converted into heat energy loss (which can no longer be used by the mechanical energy). In hydraulics, the mechanical energy consumed per unit weight
per unit time is called head loss, which is expressed in h w . The head loss
is closely related to the physical properties, internal structure, and boundary
characteristics of the liquid. From the surface, the head loss of liquid flow
can be divided into the head loss along the way and the local head loss. If the
flow channel or flow pipe is smooth, the head loss is mainly caused by the
work done by the liquid flow to overcome the boundary friction resistance,
as shown in Fig. 3.16, represented by h f , which is called the head loss along
the way. If the liquid flow is partially separated, the head loss will mainly
Fig. 3.16 Losses along the uniform flow pipeline