Velocity and pipe diameter

In summary, The question is about calculating the velocity and pipe diameter for the flow of 20m3/h of water at 20 degrees C from one storage tank to another, with a 15m elevation difference and 50m pipe length. The suggested velocity of 9.81 m/s due to gravity seems too fast and the asker is seeking help on a forum thread.
  • #1
birddog
2
0
Hello there,

Im trying to figure this assignment question and I have hit hurdle. Can someone please help with figuring out what the velocity and pipe diameter will be??

Question:
In a plant 20m3(cubic)/h of water at 20 degrees C is to flow via gravity from a storage tank to another one. the difference in elevation is 15m and total pipe length is 50m.

I thought it would be 9.81 m/s because of gravity but that seems too fast.
Can someone please help.

Thanks in advance!
 
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  • #3


Hello! I can provide some insight on the relationship between velocity and pipe diameter in this scenario. The velocity of water flowing through a pipe is dependent on several factors, including the diameter of the pipe, the pressure difference, and the fluid properties (such as density and viscosity). In this case, the velocity will be affected by the diameter of the pipe, as well as the pressure difference caused by the difference in elevation and the total pipe length.

To determine the velocity of the water, you can use the Bernoulli's equation, which states that the sum of the pressure, potential energy, and kinetic energy of a fluid in a pipe must remain constant. In this case, the potential energy (due to the elevation difference) will be converted into kinetic energy as the water flows through the pipe.

To calculate the velocity, you can use the following equation:

v = √(2gΔh)

where v is the velocity, g is the acceleration due to gravity (9.81 m/s²), and Δh is the difference in elevation (15m in this case). This will give you a velocity of 17.22 m/s, which is quite fast. This is because the pressure difference and pipe length also play a role in determining the velocity.

As for the pipe diameter, it is important to choose a diameter that can accommodate the desired flow rate without causing excessive pressure drop. This can be calculated using the Darcy-Weisbach equation, which takes into account the fluid properties, pipe length, and flow rate. Without knowing the specific details of the pipe and fluid properties, it is difficult to determine the exact diameter needed. However, you can use online calculators or consult with an engineer to determine the appropriate diameter for your specific scenario.

I hope this helps with your assignment question. Good luck!
 

1. What is the relationship between velocity and pipe diameter?

The velocity of a fluid flowing through a pipe is inversely proportional to the diameter of the pipe. This means that as the diameter of the pipe decreases, the velocity of the fluid increases.

2. How does the velocity affect the flow rate in a pipe?

The velocity of a fluid directly affects the flow rate in a pipe. As the velocity increases, the flow rate also increases, and vice versa. This is because a higher velocity means that more fluid is passing through a certain point in the pipe per unit time.

3. What is the ideal velocity for fluid flow in a pipe?

The ideal velocity for fluid flow in a pipe depends on the specific application and type of fluid. In general, a velocity between 2-4 feet per second (fps) is considered ideal for most applications. However, for high viscosity fluids, a lower velocity may be more suitable to prevent excessive pressure drop.

4. How does the pipe diameter affect the pressure drop in a pipe?

The pipe diameter has a significant impact on the pressure drop in a pipe. A larger diameter pipe will result in a lower pressure drop because the fluid has more space to flow through, reducing the resistance. Conversely, a smaller diameter pipe will result in a higher pressure drop due to the increased resistance caused by the smaller space for the fluid to flow through.

5. Can velocity and pipe diameter be adjusted to control the flow rate in a pipe?

Yes, the velocity and pipe diameter can be adjusted to control the flow rate in a pipe. By changing the diameter of the pipe, the velocity of the fluid can be altered, which in turn affects the flow rate. However, it is important to consider the limitations of the system and ensure that the velocity does not exceed certain thresholds to prevent damage or inefficiency.

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