Calculate Thrust

andreia_melo · January 14, 2019, 11:48

I'm simulation a valveles pulsejet and i want to know the thrust, i read about this but i have some questions:

-In cfd-post it is possible to know the force at the exit but can i assume that force as being the thrust? I dont find any information on how this force is calculated by Fluent.

-I have this equaion thrust=massflow*Ve+(pe-p0)*Ae, if a use this formula the pe is the static or the total pressure ate the exit? And i'm doing a 2d simulation should i pass the mass flow to a 3d since it is not equal?

LuckyTran · January 14, 2019, 12:21

The force is the integration of pressure and shear forces (probably negligible) at the boundary. It is not the thrust.

Pe is the exit static pressure.

Sorry I can't understand your last question. Just do the bookkeeping. Mass flow is going to come from a velocity and exit area also.

andreia_melo · January 14, 2019, 12:24

Thank you so much for your reply, it was really helpful!!!

January 14, 2019, 11:48	Calculate Thrust	#1
andreia_melo New Member Andreia Join Date: Jun 2018 Posts: 13 Rep Power: 8	I'm simulation a valveles pulsejet and i want to know the thrust, i read about this but i have some questions: -In cfd-post it is possible to know the force at the exit but can i assume that force as being the thrust? I dont find any information on how this force is calculated by Fluent. -I have this equaion thrust=massflowVe+(pe-p0)Ae, if a use this formula the pe is the static or the total pressure ate the exit? And i'm doing a 2d simulation should i pass the mass flow to a 3d since it is not equal?

January 14, 2019, 12:21		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,751 Rep Power: 66	The force is the integration of pressure and shear forces (probably negligible) at the boundary. It is not the thrust. Pe is the exit static pressure. Sorry I can't understand your last question. Just do the bookkeeping. Mass flow is going to come from a velocity and exit area also. andreia_melo likes this.

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January 14, 2019, 12:24		#3
andreia_melo New Member Andreia Join Date: Jun 2018 Posts: 13 Rep Power: 8	Thank you so much for your reply, it was really helpful!!!