Engr Help

Pipeflow (continued)

Turbulent Flow through single pipes -- The energy equation between two sections of pipe is:

P₁/γ + V₁²/2g + z₁ + dW/dt)/Qγ = P₂/γ + V₂²/2g + z₂ + H_L

Here dW/dt)/Qγ > 0 for pumps and dW/dt)/Qγ < 0 for turbines

Now the “head loss term”, H_L, has two parts – the major loss, HL₁, and the minor loss, HL₂.

As before the major head loss is: HL₁ = (fL/D) (V²/2g)

The minor loss HL₂ = K_LV²/2g where K_L is the loss coefficient which you obtain from

tables for fittings like elbows, bends, tees, valves, entrance sections, reentrant sections, etc.

In general there are three types of pipe flow applications.

Type 1

The flowrate or average velocity is specified. Then find the pressure

difference or head loss. Click for an example.

Type 2

The pressures at sections 1 and 2, P₁ and P₂ are specified or the head loss

is given. Then find the flowrate, Q. The unknowns are the friction factor, f,

the Reynolds Number, and the fluid velocity. Solve by iteration using a trial and

error solution. One way is to start with an assumption for f, the friction factor.

Note, you will use the Moody Chart during the solution. Click to view the

Type 3

The pressure drop and flowrate are specified. Find the required diameter of

the pipe. The unknowns are friction factor, f, the diameter of the pipe, D,

the relative roughness, ε/D, and the Reynolds Number. Solve by iteration

using a trial and error solution. Note, you will use the Moody Chart during