# Determining the flow losses through a pipe with friction

• Johan85
In summary, the conversation is discussing flow losses through a pipe with friction, specifically focusing on the Mach number reaching unity and the frictional losses after chocking is reached. The person asking the question is looking for the best way to quantify these losses, and also mentions being confident in their determination of surface roughness. It is mentioned that there is plenty of literature and tables available for estimating friction losses based on capacity and pipe ID, but the person asking the question is specifically interested in the flow model used when the Mach number reaches 1 in the Fanno flow model.
Johan85
Hi everyone,

I am trying to determine the flow losses through a pipe with friction. I understand that the Mach number increases through the pipe to unity and that the flow cannot increase when unity is reached. If the pipe is longer than the hypothetical chocking length, what would be the best way to quantify the frictional losses after chocking is reached?

Thank you so much in advance, I am very rusty when it comes to compressible flow.

Is this academic or practical? I.e. how precise of a measurement are you looking for. Pipes have different friction factors, and it is quite easy to estimate the friction losses based on capacity and pipe ID. Tons of literature and tables available for that. If it is an academic study, I'm sorry but I can't answer that right now as that is more involved than I would like to get into haha.

Travis_King,

Thanks for the reply. I am actually quite confident with the surface roughness used to determine the friction factor, since I determined that empirically. I just want to know what flow model is used after the flow reaches mach 1 when using the Fanno flow model.

Regards

## 1. What is friction loss in a pipe?

Friction loss in a pipe is the energy loss that occurs when fluid flows through a pipe due to the surface roughness of the pipe and the viscosity of the fluid. It is a result of the resistance to flow caused by the friction between the fluid and the pipe walls.

## 2. How is friction loss calculated?

Friction loss is typically calculated using the Darcy-Weisbach equation, which takes into account factors such as the length and diameter of the pipe, the flow rate, and the roughness of the pipe walls. There are also online calculators and software programs available to aid in calculating friction loss.

## 3. What are the factors that affect friction loss in a pipe?

The main factors that affect friction loss in a pipe include the velocity of the fluid, the roughness of the pipe walls, the diameter and length of the pipe, and the viscosity of the fluid. Additionally, the type of fluid being transported and the temperature can also impact friction loss.

## 4. How can friction loss be reduced in a pipe?

Friction loss can be reduced by using a larger diameter pipe, smoothing the surface of the pipe, reducing the flow rate, or using a more viscous fluid. Additionally, proper maintenance and cleaning of the pipes can also help to reduce friction loss.

## 5. Why is it important to determine the flow losses through a pipe with friction?

Determining the flow losses through a pipe with friction is important for designing efficient piping systems and ensuring that the desired flow rate and pressure are achieved. It also helps to prevent excessive energy consumption and unnecessary costs associated with pumping fluids through a pipe.

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