Determination of Static Presssure on an Airfoil

[kepler456]

I'm working with data across an airfoil and need some help.

We've got Kulite sensor data along 3 chord lengths of a certain NACA airfoil. The case is of an incompressible flow.

I need to determine the coefficient of pressure at these sensor locations using total pressure measured and I, therefore, require the static pressure.

What we have:

Free stream static pressure
Free stream total pressure
Surface total pressure

What I need:
Surface static pressure

Is this possible in any way? Thanks in advance.

 

[boneh3ad]

Wait, how do you have these Kulites mounted that they are measuring total pressure?

 

[kepler456]

They aren't? I'm just getting my hands into aerodynamics as I want to work on airfoil design and I got an internship working on this stuff. The thing is I read a few papers where they say the kulite sensors produced total pressure. I know for sure it's not static pressure as then there would have to be small holes on the airfoil to place the sensors inside? (or am I wrong).

Do you think the Kulite sensors are measuring dynamic pressure which is 0.5*rho*v^2?

 

[Baluncore]

How do you mount the sensors?
If they are mounted inside the airfoil, with the face flush with the surface of the airfoil so they do not disturb the flow, then they will read the static pressure against that surface.
If you mount them facing the airflow they will read static + dynamic pressure.

 

[boneh3ad]

They aren't? I'm just getting my hands into aerodynamics as I want to work on airfoil design and I got an internship working on this stuff. The thing is I read a few papers where they say the kulite sensors produced total pressure. I know for sure it's not static pressure as then there would have to be small holes on the airfoil to place the sensors inside? (or am I wrong).

Do you think the Kulite sensors are measuring dynamic pressure which is 0.5*rho*v^2?

You can't directly measure dynamic pressure. That's the whole purpose of a Pitot-static tube. The important question is the one that @Baluncore asked. How are your probes mounted and oriented? That determines what they measure. Just calling them Kulites doesn't tell us much because Kulite, a brand name, makes hundreds of different sensor types that can be mounted many different ways and measure any sort of pressure.

 

[Dr Transport]

They aren't? I'm just getting my hands into aerodynamics as I want to work on airfoil design and I got an internship working on this stuff. The thing is I read a few papers where they say the kulite sensors produced total pressure. I know for sure it's not static pressure as then there would have to be small holes on the airfoil to place the sensors inside? (or am I wrong).

Do you think the Kulite sensors are measuring dynamic pressure which is 0.5*rho*v^2?

I have seen Kulites mounted on the backside where the skin has been machined to allow for static pressure measurement. I took a look at the Kulite website and they list static and dynamic pressure measurement for the models LQ-062, etc... (FlightTest.pdf)