Help on how to plot the Rayleigh line for a flow?

In summary, the Rayleigh line is a plot of the change in entropy as a function of the change in pressure and temperature at a constant Mach number. To plot this line, you will need to use the equation s2/s1 = (p2/p1)^((gamma-1)/gamma) * (T2/T1)^(-1/(gamma-1)) and choose a range of p2 and T2 values to plot.
  • #1
kawf
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0

Homework Statement



I need to plot the Rayleigh line for a flow that has the following conditions at one point
(Perfect gass assumption holds, R=287 J/kgK, gama=1.4)
p = 101.3 kPa
T = 300 K
s = 6.867*10^3 J/kgK
M = .25

My question is what equation am I actually supposed to plot for a Rayleigh line?

Any help is appreciated. TIA

Homework Equations



http://upload.wikimedia.org/math/7/0/e/70eca7a87051faef8ba16009e8f46fe2.png

The Attempt at a Solution



So far i have tried plotting the change in entropy as a function of mach number but that does not seem to be right (seen here as S_R http://upload.wikimedia.org/math/7/0/e/70eca7a87051faef8ba16009e8f46fe2.png)
 
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  • #2


After doing some research, it seems that the Rayleigh line is a plot of the change in entropy (s) as a function of the change in pressure (p) and temperature (T) at a constant Mach number. In order to plot this, you will need to use the following equation:

s2/s1 = (p2/p1)^((gamma-1)/gamma) * (T2/T1)^(-1/(gamma-1))

where s is entropy, p is pressure, T is temperature, and gamma is the specific heat ratio (in this case, 1.4). M is the Mach number, which is already given as 0.25.

To plot the Rayleigh line, you will need to choose a range of p2 and T2 values and use the equation to calculate the corresponding s2 value. Then, plot s2 as a function of p2 and T2. This will give you a curve that represents the change in entropy at a constant Mach number.

I hope this helps! Let me know if you have any further questions.
 

1. What is the Rayleigh line for a flow?

The Rayleigh line is a graphical representation of the stagnation state of a compressible flow. It shows the relationship between the stagnation temperature and stagnation pressure of a fluid at various points along a streamline.

2. How do I plot the Rayleigh line for a flow?

To plot the Rayleigh line, you will need to have the necessary data for the fluid properties, such as density, temperature, and pressure. Using this data, you can use the Rayleigh flow equations to calculate the stagnation temperature and pressure at different points along the streamline. Then, you can plot these values on a graph to create the Rayleigh line.

3. What are the equations used to plot the Rayleigh line?

The equations used to plot the Rayleigh line are the Rayleigh flow equations, which are based on the conservation of energy and mass. These equations take into account the changes in temperature, pressure, and velocity along a streamline to determine the stagnation state of the flow.

4. What information can I get from the Rayleigh line?

The Rayleigh line provides valuable information about the stagnation state of a compressible flow. By plotting the Rayleigh line, you can determine the conditions at different points along a streamline, including the stagnation temperature, stagnation pressure, and Mach number. This information can be used to analyze the performance of a fluid flow system and make design decisions.

5. What are some practical applications of the Rayleigh line?

The Rayleigh line has several practical applications, such as in the design of gas turbine engines, supersonic aircraft, and rocket engines. It is also useful in analyzing the performance of compressible flow systems, such as in gas pipelines and steam turbines. Additionally, the Rayleigh line can be used to study the effects of shock waves and determine the maximum possible flow velocity in a compressible flow system.

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