# Calculate Pressure & Speed of Submerged Water Jet 100mm Away

• JoachimSa
In summary, the conversation is about calculating the pressure and speed of a high pressure water jet hitting an object 100 millimeters away from the nozzle opening. The nozzle will be used in salt water at a depth of 100 meters and has a diameter of 2 millimeters. There is no simple formula for this calculation and it is recommended to refer to publications for guidance. The velocity of the water jet varies with distance and radial distance from the flow centerline. The geometry of the object also affects the impact of the water jet, especially in the case of a fresh water jet in salt water. Overall, there is no easy solution to this problem.

#### JoachimSa

I am trying to calculate at what pressure and speed water from a high pressure water jet will hit an object 100 millimeters away from the nozzle opening, but i can't figure it out.

The nozzle will be used at approximately 100 meter below sea level in salt water. Its a circular nozzle with a diameter = 2 millimeters. The water from the water jet is at 400 bar and with a flow of about 60 liters per minute.

Does anyone know what formula to use?

I don't think there is a simple formula where you could just plug in numbers. There are certainly publications about that setup, you could check what they did to simulate the system.

A turbulent jet of liquid discharged into a large volume of the same liquid spreads out in a cone shape . Tests and simulations have determined that assuming a half angle of 11.8 deg for the cone is adequate for most practical calculations . Problem is that the velocity of flow varies not only with distance from nozzle but also with radial distance from the flow centreline . Velocity is highest on the flow centreline and fades away to zero at larger radial distances .

What actually happens when jet impinges on an object depends on the geometry of the object .

• mfb and russ_watters
This becomes doubly difficult if your water jet is fresh water discharging into salt water, as it is now a turbulent buoyant jet. Generally speaking there is no simple solution to this problem (buoyant or not).

## 1. How do you calculate the pressure of a submerged water jet?

The pressure of a submerged water jet can be calculated using the Bernoulli's equation, which states that the pressure of a fluid decreases as its speed increases. To calculate the pressure, you will need to know the speed of the water jet, the density of the fluid, and the distance from the water jet's source.

## 2. What is the formula for calculating the speed of a submerged water jet?

The formula for calculating the speed of a submerged water jet is v = √(2gh), where v is the speed, g is the acceleration due to gravity, and h is the distance from the water jet's source. This formula is derived from the Bernoulli's equation by solving for velocity.

## 3. Can the distance from the water jet's source affect the pressure and speed?

Yes, the distance from the water jet's source can affect the pressure and speed. According to the Bernoulli's equation, as the distance from the source increases, the pressure decreases while the speed increases. This is because the energy of the water jet is conserved, and as it travels further, it has more distance to increase its speed.

## 4. What unit of measurement is used for pressure and speed in this calculation?

The unit of measurement for pressure is usually expressed in Pascal (Pa) or pounds per square inch (psi), while the speed is commonly measured in meters per second (m/s) or feet per second (ft/s). In some cases, other units such as bar or kilopascal may also be used for pressure.

## 5. Can this calculation be applied to other fluids besides water?

Yes, this calculation can be applied to other fluids besides water as long as the fluid's density and properties are known. The Bernoulli's equation is a fundamental principle in fluid mechanics and can be applied to any fluid as long as the necessary parameters are known.