Calculating Flow Rate: A Guide for Sevy

In summary, the conversation is about solving a question regarding the flow rate of water from a tank through a pipe with given dimensions and factors. The speaker is seeking guidance on how to approach the question and provides some equations and a lecture as potential resources.
  • #1
Sevy35
2
0
I'm trying to get my head around this question but having missed a few lecture through illness I'm going round in circles.

Water is fed from a tank 12m above ground along a pipe 200 m long with a diameter of 125mm. Pipe frictyion factor is 0.008. K factors for the fittings, (tank exit, valve etc) add up to 3.3. I'm being asked to find the flow rate in kg/s and donlt knwo where to start.

I don't want the answer, just some direction of how to approach it.

Regards

Sevy.
 
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  • #2
Welcome to PF.

Basically you are going to have the potential energy of the drop (12m) that is given in ρgh that will go into kinetic energy of the flowing liquid that will be 1/2ρV².

But that's not all it goes into because they have given you the frictional factor that will be experienced over the 120m of run length. And you have the K factor for the pipe system that takes into bends and such that they would give you of 3.3.

The contribution to friction loss I think looks like

Frictional resistance energy loss = ½ ρ*f (L/d) x (V²)

L is Length and d is diameter and f is your frictional factor.

The K factor contributes an additional energy loss of ½ ρ*K*V²

where K is your K factor.
 
  • #3
Here is a lecture that touches on some of the basics. (About 30 minutes in.):

https://www.youtube.com/watch?v=ngABxM7jl0Q
 

1. What is flow rate and why is it important to calculate?

Flow rate is the measure of how much fluid or gas is moving through a given area in a specific amount of time. It is important to calculate because it helps us understand and predict how fluids will behave in various systems, such as in plumbing, irrigation, or industrial processes.

2. How do I calculate flow rate?

Flow rate is typically calculated using the formula Q=V/t, where Q is the flow rate in volume per time, V is the volume of fluid or gas, and t is the time it takes for the fluid or gas to pass through a specific area. However, there may be variations in the formula depending on the specific system or application.

3. What units are used to measure flow rate?

Flow rate can be measured in a variety of units, depending on the system and the application. Some common units include liters per second, gallons per minute, cubic meters per hour, and cubic feet per minute. It is important to use the appropriate units for the specific calculation to ensure accuracy.

4. How can I measure flow rate in a closed system?

In a closed system, where the fluid or gas is confined and cannot escape, flow rate can be calculated using pressure and cross-sectional area. The formula for this is Q=A√(2gh), where Q is the flow rate, A is the cross-sectional area, g is the acceleration due to gravity, and h is the height of the fluid column.

5. How can I ensure accurate flow rate calculations?

To ensure accurate flow rate calculations, it is important to use the correct formula and units for the specific system. It is also important to measure and record all variables accurately, such as volume, time, pressure, and cross-sectional area. Regular maintenance and calibration of measuring instruments can also help maintain accuracy.

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