Hello. I want to conduct an experiment in the wind tunnel for measurement of drag forces. Currently we are considering which setup would be able to give an accurate measurement. In the attachment show two possible setup. Are the drag forces measured from these two set up going to be the same? Or which set up is better? Any suggestions and explanations will be very useful. Thank you very much.
I woud like to clarify that instead of a strain gauge, we are using a double bending beam force sensor. thanks!
Hello Jessica Tay Ying Ling , having a quick look at the configurations, I think that the first one (on the left) is more convenient if you are using a bending beam sensor. You may need to isolate the beam from the air flow so that only the sphere location is hit by the wind. You can also replace the sphere by a hollow hemisphere with the concave surface facing the wind which is very suitable for this type of study.
I agree with response of Jessica. I had used this sensor in my project
Hello Ahmad Hajjar , thank you for the response. Can you explain what do you mean by more convenient? We tested the drag coefficient of a sphere and a circular plate with the set up on the right, but our Cd were a little lower than what was reported in the literature.. Do you think it could be due to the set up? I could of course test it with the other set up but I was wondering if there is an explanation as to which set is is more suitable. Thanks!
Jessica Tay Ying Ling I think that the configuration on the left iss more convenient because it was easier to set up with a bending beam sensor, but if you already installed the second configuration then it should be fine. I am not sure how different the result would be without testing. Cd was little lower, what error % did you get with the second configuration?
Hello Ahmad Hajjar , i'm not too sure what do you mean by error %, but from our testing with a sphere of 20cm in diameter, our cd values plateau at 0.41. I know that a range of values should be acceptable but I just wanted to see if set up configuration mattered.
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