Calculating Velocity in a Pipe: Flow Rate 0.01, Diameter 90mm

In summary, the conversation discusses finding the velocity within a pipe using the flow rate and diameter. The equation V = Q/A is mentioned, where A is found using A = pi/4 x D^2. The resulting value of A should have units of mm^2.
  • #1
fowler2k
6
0
I need to find the velocity within a pipe , I know the flow rate and diameter

Flow rate =0.01
Diameter =90mm

Am I correct in thinking to use V =Q/A

Where A is found using A=pi/4 x D^2

Using this I got A =0.0064m but somehow this does not seem quite right to me

Can anybody please tell me where I am going wrong please

Thanks
 
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  • #2
Please include units for all quantities. How else can we tell what these numbers mean?
 
  • #3
0.01m3 s-1
 
  • #4
fowler2k said:
I need to find the velocity within a pipe , I know the flow rate and diameter

Flow rate =0.01
Diameter =90mm

Am I correct in thinking to use V =Q/A

Where A is found using A=pi/4 x D^2

Using this I got A =0.0064m but somehow this does not seem quite right to me

Yes, it's not quite right. Your answer is a length...you want an area.
 
  • #5
Ah so it should be m^2 ?
 
  • #6
What are the units for your flow rate?

And also, Your equation for area includes the term D^2 which implies the diameter is being squared, so your answer for area should have the units mm^2.
 

1. How do you calculate velocity in a pipe with a flow rate of 0.01 and a diameter of 90mm?

To calculate the velocity in a pipe, you can use the formula:
velocity = flow rate / (area of pipe)
First, convert the diameter of 90mm to meters by dividing by 1000. This gives a diameter of 0.09m.
Next, calculate the area of the pipe using the formula for the area of a circle:
area = π * (radius)^2
The radius of the pipe is half of the diameter, so the radius would be 0.045m.
Plug in the values into the initial formula to get:
velocity = 0.01 / (π * (0.045)^2)
Solve for velocity to get the answer.

2. What is the flow rate in a pipe with a velocity of 5 m/s and a diameter of 90mm?

To calculate the flow rate, you can use the formula:
flow rate = velocity * (area of pipe)
Using the same steps as in question 1, we can find the area of the pipe to be approximately 0.012m^2.
Plug in the values into the formula to get:
flow rate = 5 * 0.012
Solve for flow rate to get the answer.

3. How does changing the diameter of a pipe affect the velocity?

Changing the diameter of a pipe can affect the velocity in two ways. First, if the flow rate remains constant, increasing the diameter of the pipe will decrease the velocity. This is because a larger diameter pipe has a larger area, so the same amount of fluid will take longer to pass through. Conversely, decreasing the diameter of the pipe will increase the velocity. Secondly, if the flow rate is changed to maintain a constant velocity, then increasing the diameter will also increase the flow rate, and vice versa.

4. What units are typically used to measure velocity and flow rate in pipes?

Velocity is typically measured in meters per second (m/s) or feet per second (ft/s). Flow rate is typically measured in cubic meters per second (m^3/s) or cubic feet per second (ft^3/s).

5. How accurate are the calculations for velocity and flow rate in pipes?

The accuracy of the calculations for velocity and flow rate in pipes depends on the accuracy of the input values and the assumptions made in the calculations. For example, the calculations assume that the fluid is incompressible, the pipe is smooth, and the flow is steady. Any deviations from these assumptions can affect the accuracy of the calculations. Additionally, the accuracy can also be affected by factors such as turbulence, friction, and changes in the fluid's properties. It is important to carefully consider all factors and use accurate input values to ensure the most precise calculations.

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