Stagnation Point Heating - enthelpy at the wall

In summary, the conversation discusses using the Fay-Riddell correlation to solve for stagnation point heat transfer and the confusion surrounding the enthalpy at the wall. The speaker is considering using the eqair applet to find the enthalpy using the pressure and density of the flow at the wall. They also mention an example from class where the enthalpy at the boundary layer edge and after the shock wave were assumed to be the same. The speaker is unsure if they are using the applet correctly and is seeking help in solving for the enthalpy at the wall.
  • #1
roldy
237
2
Using the Fay-Riddell correlation, I can solve for the stagnation point heat transfer but I'm running into a snag. I'm doing this for a thermo-chemical equilibrium assumption. I'm confused with the enthalpy at the wall. I'm assuming a wall that is not adiabatic, but at some wall temp Tw. If I know what the pressure and density of the flow at the wall, could I use the eqair applet http://www.dept.aoe.vt.edu/~devenpor/tgas/ and solve for the enthalpy using the pressure and density as the inputs? I've posted an example from class.

I thought that I could use this but when I tried it and it didn't work out as I had planned. Following the example that my professor posted, he assumed that the enthalpy at the boundary layer edge (he) is the same as the enthalpy right after the shock wave (h2). The enthalpy after the shock wave was found using the eqair applet.

I'm I correct in using the eqair applet again for the wall?

I tried working the example problem but I am not getting the results that my professor is getting. I tried using the eqair applet for using the wall conditions. and I get h wall = 1.6227E6. I solved his example in reverse to solve for the h wall that he is using and I get h wall = 2.469999778E7. He doesn't show what value he is using for the wall enthalpy.
 

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  • #2
I'm not sure if I'm using the eqair applet correctly or if I should be using a different approach to solve for the enthalpy at the wall. Any help would be appreciated.
 

1. What is stagnation point heating?

Stagnation point heating, also known as stagnation enthalpy at the wall, is a phenomenon that occurs when a fluid flows over a solid surface and is brought to a complete stop, creating a region of high pressure and temperature at the point where the fluid meets the surface.

2. How does stagnation point heating affect the fluid flow?

Stagnation point heating can significantly alter the behavior of the fluid flow. The increase in temperature and pressure at the stagnation point can lead to changes in the density, viscosity, and other properties of the fluid, which can then affect the overall flow patterns and forces exerted on the solid surface.

3. What factors influence stagnation point heating?

The amount of stagnation point heating experienced by a fluid depends on several factors, including the flow velocity, the properties of the fluid and the solid surface, and the angle at which the fluid meets the surface. Additionally, the shape and roughness of the solid surface can also affect stagnation point heating.

4. Why is stagnation point heating important in aerodynamics and heat transfer?

Stagnation point heating plays a crucial role in aerodynamics and heat transfer, as it can impact the performance and efficiency of various systems. For example, in aircraft design, understanding and controlling stagnation point heating is essential for reducing drag and improving flight efficiency. In heat transfer applications, stagnation point heating can affect the efficiency of heat exchangers and other thermal systems.

5. Can stagnation point heating be controlled or mitigated?

Yes, stagnation point heating can be controlled or mitigated through various techniques such as using heat-resistant materials for the solid surface, altering the flow velocity, or changing the angle at which the fluid meets the surface. Additionally, advanced modeling and simulation techniques can also help predict and manage stagnation point heating in different applications.

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