The engineer’s interest in pipes.

Engineers become involved with pipe work in many different applications. In almost every case the engineer will, at some stage, will be required to determine either the smallest size of pipe to convey a given flow, or the maximum flow that can be carried by an existing pipe. We shall find that, in order to do this, data on the friction loss in steady flow through pipes is required. However we need to have some overall way of dealing with pipes. We are dependent on what others have already done and we do not need to proceed as if we were starting from scratch.

 

Once more the methods are dependent on the use of the energy equation. It is used in the following form :-

               + the loss between 1 and 2

The flow in a pipe is then considered to be a special sort of flow line where the path of the particles forming the flow is determined by the path of the pipe. Then the total head equation is applied to two sections 1 and 2 of the flow in a pipe, where 2 is downstream of 1. Then we choose to regard the pressure and velocity as uniform across every section of the pipe and we also measure potential energy to the centre line.[1] The same decisions are usually taken for ducts in general. This is described in short form by saying that the system is to be regarded as having one-dimensional flow, that is, that the measurable quantities change along the pipe but not across it.

 

Given this method of adapting the total head equation to a pipe we must consider the conditions that lead to steady flow.