Finding Separation Point: Pressure Coeff vs Angle Graph

[knight92]

Hi there, I just wanted to know how to find out where the separation point is on a Pressure Coefficient against Angle Graph ? I did some research and found out something called an adverse pressure gradient what does it mean ? I know that it does promote a separation point so would a separation point be where the graph has spikes so the gradient goes from negative to positive ? Please tell me according to the graph because right now I am thinking the separation point is at around 1.4,-1.3 [x,y] on the blue lined graph and can there be multiple separation points ? so confused.

I have attached an image for my experimental Pressure Coefficient vs Angle graph and a theoretical pressure coefficient graph. I thought the theoretical pressure coefficient graph didnt show a separation point because there isn't one but it has negative and positive gradients too. Please help and thank you.

 

[boneh3ad]

An adverse pressure gradient means that pressure is increasing as you move downstream (aka the flow is decelerating). In relation to your plots, for the first $\pi$ radians, it is any place where the slope of your curve is positive.

The separation points are marked by the points where your Cp distribution goes flat, so roughly $\phi \approx 1.75,4.25$ in your case. The region where it is flat is the separated region.

 

[NatSusan]

Hi there,

Finding the separation point on a Pressure Coefficient against Angle Graph can be a bit tricky, but there are a few things you can look for to identify it.

First of all, an adverse pressure gradient means that the pressure is increasing as the flow moves in the opposite direction. This can cause the flow to slow down and potentially separate from the surface. So, you are right in thinking that a separation point would occur where the graph has spikes and the gradient goes from negative to positive.

In terms of your specific graph, it's difficult for me to pinpoint the exact separation point without seeing the full graph and knowing more about your experimental setup. However, it looks like the separation point could be around 1.4,-1.3 [x,y] as you mentioned. And yes, there can be multiple separation points depending on the shape and angle of the surface.

As for the comparison between your experimental and theoretical graphs, it's important to keep in mind that the theoretical graph is just a prediction and may not perfectly match your experimental results. However, the fact that both graphs show negative and positive gradients does suggest that there could be a separation point.

I hope this helps and please let me know if you have any other questions. Good luck with your research!