Lesson 8 - Control of Fluid Flow 1
This lesson will consider two main classifications of pumps: centrifugal and positive displacement. These will be introduced together, with aspects of their design and operation. The lesson will also pull together various fluid mechanics concepts from previous lessons, such as the Darcy-Weisbach equation and the use of loss-coefficient to calculate pressure drops in pipe systems. It will use this information to then size pumps for particular pipe systems.
Point of Reflection – Reconvene
Welcome back! So, what were your thoughts?
Well hopefully you noticed the bold clues of a rotating impeller and a stationary casing? So, we have a rotating shaft passing through a stationary casing, and within the casing is the liquid which is being pumped under pressure. How do we ensure that the liquid remains within the casing whilst the impeller drive shaft passes through the casing and is free to rotate? We need to know whether the hole in the casing, through which the drive shaft passes, leaks.
With careful design and maintenance, the hole will not leak as we can seal it, and also allow the shaft to rotate within that seal. To do this, we use a device called a seal.