Compressible Flow, Pressure and Mass Flowrate

In summary, the conversation discusses a lab report on compressible flow through rotameters. The experiment involves using an upstream and downstream rotameter with a fixed orifice created by a needle valve. The results show that at pressures above 13psig, the flow is sonic and follows a straight line on a graph, but at subsonic speeds, it does not follow a curve. The person is struggling to explain this and is advised to research "choked flow" for further understanding.
  • #1
Calum Blair
1
0
I am doing a lab report and it is to do with compressible flow through rotameters. An upstream and downstream rotameter to measure flow rate with a needle valve between the two. The needle valve acts as a fixed orifice in one part of the experiment. Then the inlet pressure is altered.

Plotting pressure against mass flow rate yields a graph where above 13psig the flow is sonic and it follows a straight line. However at subsonic speeds it no longer follows a curve. I am struggling to explain why this is the case?

Any ideas?
 
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  • #2
Google "choked flow." That ought to set you down the right path.
 

Related to Compressible Flow, Pressure and Mass Flowrate

1. What is compressible flow?

Compressible flow is a type of fluid flow in which the density of the fluid changes due to changes in pressure and temperature. This type of flow is commonly seen in gases, as opposed to incompressible flow which is seen in liquids.

2. How does pressure affect compressible flow?

As the pressure of a fluid increases, its density also increases. This means that in compressible flow, as the pressure increases, the density of the fluid also increases. This can cause changes in the flow behavior and velocity of the fluid.

3. What is the relationship between pressure and mass flowrate?

The mass flowrate of a fluid is directly proportional to the pressure of the fluid. This means that as the pressure increases, so does the mass flowrate. This relationship is important in understanding and predicting flow behavior in compressible flow systems.

4. How is compressible flow different from incompressible flow?

The main difference between compressible and incompressible flow is the behavior of the fluid under changes in pressure. Incompressible flow assumes that the density of the fluid remains constant, while compressible flow takes into account the changes in density due to changes in pressure.

5. What factors affect the mass flowrate in compressible flow?

The mass flowrate in compressible flow is affected by the pressure, temperature, and density of the fluid. It can also be influenced by the geometry of the system and any obstructions or changes in the flow path. Additionally, the properties of the fluid, such as its viscosity and compressibility, can also impact the mass flowrate.

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