Calculate Force on Steel Wall from Water Flow

In summary, the conversation discusses how to determine the force exerted by water exiting a pipe onto a steel wall. The water's flow rate, velocity, and pressure are all factors that can be used to calculate the force, with methods such as Bernoulli's equation and the rate of change of momentum. The discussion also touches on the impact of static pressure and the simplified version of the calculation.
  • #1
neilmark
2
0
We have a water pipe which is 750mm diameter assumed running full with a flow rate of 152l/s. When the water exits the pipe there is a steel wall approx 1.2m in front of it and I need to determine the force that the water exerts on the wall?

I have claulcated that the water is running at 0.067m/s.

Can anyone help?
 
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  • #2
Do you know how to work out the pressure of the fluid leaving the pipe?
 
  • #3
Not sure I follow you there??
 
  • #4
Pressure is force per unit area.

If you know the pressure and the area of the end of the pipe you can get the force at the point of leaving the pipe.

I suppose if you know the mass flow rate you could get the momentum also.
 
  • #5
Static pressure at the end of the pipe is zero, but there is velocity pressure, which you can calculate with Bernoulli's equation.
 
  • #6
By the time you are 1m away from the nozzle, I think you can neglect the static pressure as the jet will have spread outwards as soon as it exits the hole. All that counts is the force needed to stop the mass of water as it hits the wall.

The Force is the rate of change of Momentum, P.
P = Speed change X Mass
and Force = P/time
So Force = Speed change X Mass per second
Work out the speed of the jet (Volume per second / Area of Pipe) now multiply by the mass per second (Volume in one second X density). Assuming the water is brought to rest, then the change is from P to zero, this is the value of the force. (Someone will point out that there is a simplified version of this but I think this is more straightforward)
 

1. How do you calculate the force on a steel wall from water flow?

To calculate the force on a steel wall from water flow, you will need to know the velocity of the water, the density of the water, and the surface area of the wall. The formula for calculating force is F = ρ * v^2 * A, where ρ is the density, v is the velocity, and A is the surface area of the wall.

2. What is the density of water?

The density of water varies depending on its temperature and salinity, but on average it is approximately 1000 kg/m^3. It is important to use the correct density value for your specific water flow calculation.

3. How do I measure the velocity of water?

The velocity of water can be measured using a flow meter, which can be placed in the water flow to measure its speed. Another option is to use a pitot tube, which measures the pressure difference between the water flow and still water to determine the velocity.

4. Why is it important to calculate the force on a steel wall from water flow?

It is important to calculate the force on a steel wall from water flow to ensure that the wall can withstand the force and not be damaged. This is especially important for structures like dams, bridges, and offshore platforms that are constantly exposed to water flow.

5. How can I reduce the force on a steel wall from water flow?

There are several ways to reduce the force on a steel wall from water flow. One option is to increase the surface area of the wall to spread out the force. Another option is to redirect the water flow using barriers or diversion channels. Additionally, the shape and orientation of the wall can also impact the force on it from water flow.

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