# Calculating Flow Rate in a Converging Nozzle System

• npc214
In summary, the speaker is seeking help in calculating the flow rate of a fluid system with a pressure source and a converging nozzle. They have tried to simplify the system and are using a pressure sweep in Excel. They are unsure how to calculate the flow rate and are considering using the equations hL = [k(v)^2]/(2g) and ΔP = (ρ*hL)/144 or q = K*A*(2*144*g*ΔP/ρ). They also have posted the question on a forum for assistance.
npc214
Hey everyone,

I have a fluid system of water coming from a pressure source. Then there is a converging nozzle, which I have calculated the resistance coefficient using Crane's Manual and it has an outlet to the atmosphere.
I have tried to simplify the system. The full system is a pressure source, converging nozzle which has outlet into original diameter at converging nozzle inlet followed by hose to outlet to atmosphere. (this is like a fire hose system - slightly different for my actual application)​

The pressure of the pressure source is my independent variable, I am doing a sweep in excel. So if it helps for simplicity, you can assume the pressure is 100 psi.

How do I calculate the flow rate (in GPM)? Do I need to take away the outlet of the system?

Currently I am thinking using:

hL = [k(v)^2]/(2g)
ΔP = (ρ*hL)/144
then what for q??

Or I am thinking q = K*A*(2*144*g*ΔP/ρ)
but then what is ΔP?? is it the pressure drop across the converging nozzle or is it the pressure drop from the inlet to outlet at atmospheric?

## 1. What is flow rate?

Flow rate is a measure of how much fluid is moving through a specific point in a given amount of time. It is usually measured in units of volume per unit of time, such as liters per second or gallons per minute.

## 2. How is flow rate calculated?

Flow rate is calculated by dividing the volume of fluid that has passed through a point by the amount of time it took for the fluid to pass through that point. This can be represented by the formula: flow rate = volume / time.

## 3. What factors affect flow rate?

Several factors can affect flow rate, including the size and shape of the pipe or channel through which the fluid is flowing, the fluid's viscosity, and the pressure and temperature of the fluid. Other factors such as obstructions or changes in elevation can also impact flow rate.

## 4. How is flow rate measured?

Flow rate is typically measured using instruments such as flow meters or flow sensors. These devices can be placed in the fluid's path to measure the volume of fluid passing through in a given amount of time. Flow rate can also be calculated using pressure and velocity measurements.

## 5. Why is flow rate important?

Flow rate is an important measurement in many industries, including manufacturing, engineering, and environmental science. It can help determine the efficiency of a system or process, identify potential issues or blockages, and ensure that the appropriate amount of fluid is being delivered or used. Flow rate is also important in understanding and managing water and air pollution, as well as in monitoring and controlling the flow of fluids in our everyday lives.

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