Specified angle flow rate measurement in a pipe.
 

In a 360 degree cylinder pipe I divide the cross section into 72 pieces,namely,each angle is 5 degree.In the experiment ,I measure the veloctiy profile of the straight path from 10 degree to 190 degree compared with that from 0 degree to 180 degree in a cylinder pipe. My question is how to measure the velocity profile at the specified θ angle in the pipe.(ps:not the flow rate across all the cross section but the specified θ angel.) Thank you sincerely.