What do we mean by hydraulically smooth pipes?

Question

What do we mean by hydraulically smooth pipes?

Answer 1

The surface roughness of piping inner diameter has a great influence on the friction when fluid flows in the piping. Using a smooth piping reduces this resistance

Answer 2

The flow rate inside a pipe that will produce laminar(No turbulence) flow.   The physical smoothness plays a part but need not be as smooth as glass.   A concrete, cast iron , copper and glass pipe can all produce laminar flow.  The flow rate at which turbulence begins (no longer hydraulically smooth) will depend upon the surface texture where rougher surfaces will cause turbulence to occur at lower flow rates compared to a smoother material.    Raise teh flow rate enough and your will eventually get turbulence.

So to have hydraulically smooth pipes you would need to spec no only the material but diameter as well to ensure laminar flow upto the max expected flow rate. Also any turbulence inducing fittings would also be included. For example a bar grate in a storm water system could be installed such that hydraulically smooth flow is maintained for low flow rates.   (The water ca easily pass arround the bars). During the high flows a storm would produce the bar grate would cause a restriction and you would no longer have smooth flow.

Answer 3

No imperfections

Answer 4

Low resistance to flow