Calculating Reynolds Number for Turbulent Gas Flow

In summary: Hello turbulence freaksIn summary, the Reynolds equation holds for gas flows, but property values must be corrected for compressibility and temperature.
  • #1
Mancunian
1
0
Hello

Im currently looking at turbulent gas flow in circular pipe sections by calculating the Reynolds the number. Does the Reynolds equation hold for say flow of an ideal gas - air as it does for a real fluid say water.

This may sound like a stupid question and I supose I've got my head in a twist between the difference of a real fluid and a ideal gas, but I would like to know if I can calculate the reynolds number for a gas - in the same way I would say water through a pipe.

Any help would be greatly appreciated

A very confused Mancunian
 
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  • #3
Reynolds number definition does not change due to fluid state that I have ever seen. The trick comes in, when dealing with gases, is getting accurate property values. An ideal gas is pretty easy, but it gets tricky when going away from the ideal model and you have to start correcting for pressure (compressibility) and temperature. At work, our aero guys have proprietary aero-thermo codes specifically for calculating properties that are non ideal in our engine decks.
 
  • #4
Mancunian said:
Does the Reynolds equation hold for say flow of an ideal gas - air as it does for a real fluid say water.
calculate the reynolds number for a gas - in the same way I would say water through a pipe.
A confused Mancunian
Hello Mancunian
don't be confused, Gases and fluids are measured equally in their way of getting turbulent or remaining laminar... That is hydrodynamics, yet remarcs of non ideal gases (electrically?) or ideal fluids (non -Stokes) remain of consequence.
greetings Janm
 
  • #5
Hello turbulence freaks
You have to admit that yesterday waterballet is not only a olympic game anymore but entried entertainment. I know you want to hear here about turbulent gas flow, more difficult to see (coloured gasses?) then turbulent water (still remaining best drawing of L. daVinci) yet hanging water bassins brought to the public in Russia as an experiment for multimedia...
I was astounded...
And for calculating reynolds number for gasses: The Reynolds number is a dimensionless number. The way I was tought about that is: you can make a model with the same Reynolds number with very varied number of dimensions but if the Reynolds number is the same you get the transition of laminar to turbulent or the other way around in the same way as a model which uses the whole North Sea saying Norway has won...
Sorry for eventually poetic changes, but I am still impressed of the ESC...
greetings Janm
 

What is Reynolds Number and why is it important in studying turbulent gas flow?

Reynolds Number is a dimensionless quantity used to determine the type of flow (laminar or turbulent) occurring in a fluid. In the context of gas flow, it is used to understand the transition from smooth, predictable flow to chaotic, unpredictable flow. It is a crucial parameter in fluid dynamics and helps in predicting the behavior of fluids in various systems, including pipes, pumps, and turbines.

How is Reynolds Number calculated for turbulent gas flow?

Reynolds Number (Re) is calculated by multiplying the fluid's density (ρ), velocity (V), and characteristic length (L), and dividing it by the fluid's dynamic viscosity (μ). The formula is: Re = ρVL/μ

What is the significance of the characteristic length in calculating Reynolds Number?

The characteristic length represents the size of the object through which the fluid is flowing. It is an essential factor in calculating Reynolds Number as it helps determine the size of the boundary layers in the fluid flow. The boundary layers play a crucial role in determining the type of flow (laminar or turbulent) occurring in the fluid.

What is the range of values for Reynolds Number in turbulent gas flow?

Reynolds Number can vary from very low values (less than 2000) for laminar flow to very high values (greater than 4000) for turbulent flow. In the range of 2000 to 4000, the flow may be transitional, exhibiting characteristics of both laminar and turbulent flow. Generally, a higher Reynolds Number indicates a more turbulent flow.

What are some practical applications of calculating Reynolds Number for turbulent gas flow?

Reynolds Number is used in various industries, including aerospace, automotive, and energy, to design and optimize systems involving fluid flow. It helps in predicting the pressure drop, heat transfer, and flow patterns in pipes, ducts, valves, and other complex systems. It is also used in the development of new technologies, such as microfluidics, which have applications in medical devices and drug delivery systems.

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