Coefficient of Drag of a projectile for different Mach Numbers

CdProjectile · January 12, 2018, 13:09

Hi guys,

I am in need of some help with a simulation. I am looking to do a simulation to find the coefficient of drag around a 155mm projectile for multiple Mach Numbers. I am approaching this as a 2D simulation. Currently any value I get for CD is blatantly wrong (in the thousands but should obviously be below 1). For low velocities of around 3 m/s the result would appear correct although obviously projectile travel much faster than this. At high velocities the result i get is in the millions so is obviously not correct.

ANyone have any ideas that can help me in my problem.

I have been following an adapting these two tutorials as i go along in the hope of getting things correct:

https://confluence.cornell.edu/displ...+Physics+Setup

https://confluence.cornell.edu/displ...+-+Step+4+*New

I also hope to get a illustration of the pressure around the projectile that shows how the pressure at the back of the projectile is lower due to the fact it is a blunt body.

Thanks.

DEd · January 12, 2018, 16:52

In order for the Cd to be correct you need to specify the right reference values.

CdProjectile · January 12, 2018, 17:50

Quote:

Originally Posted by DEd

In order for the Cd to be correct you need to specify the right reference values.

What values are you talking about and where do i go to change them. Using ansys 18.2 currently

DEd · January 12, 2018, 18:17

The "Reference values" in the tree view. Can also be found under the tab "Setting up physics" and "Reference values"

January 12, 2018, 13:09	Coefficient of Drag of a projectile for different Mach Numbers	#1
CdProjectile New Member Join Date: Dec 2017 Posts: 5 Rep Power: 9	Hi guys, I am in need of some help with a simulation. I am looking to do a simulation to find the coefficient of drag around a 155mm projectile for multiple Mach Numbers. I am approaching this as a 2D simulation. Currently any value I get for CD is blatantly wrong (in the thousands but should obviously be below 1). For low velocities of around 3 m/s the result would appear correct although obviously projectile travel much faster than this. At high velocities the result i get is in the millions so is obviously not correct. ANyone have any ideas that can help me in my problem. I have been following an adapting these two tutorials as i go along in the hope of getting things correct: https://confluence.cornell.edu/displ...+Physics+Setup https://confluence.cornell.edu/displ...+-+Step+4+*New I also hope to get a illustration of the pressure around the projectile that shows how the pressure at the back of the projectile is lower due to the fact it is a blunt body. Thanks.

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January 12, 2018, 16:52		#2
DEd Member Daniel Edebro Join Date: Feb 2016 Location: Gothenburg Posts: 41 Rep Power: 10	In order for the Cd to be correct you need to specify the right reference values.

January 12, 2018, 18:17		#4
DEd Member Daniel Edebro Join Date: Feb 2016 Location: Gothenburg Posts: 41 Rep Power: 10	The "Reference values" in the tree view. Can also be found under the tab "Setting up physics" and "Reference values"