# Aerospace How do I know what the separation point is on a Pressure Coefficient vs Angle graph ?

1. Apr 19, 2012

### 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 isnt one but it has negative and positive gradients too. Please help and thank you.

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• ###### IdealCPvsAngle.png
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2. Apr 19, 2012

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.