Ansys Fluent: CFD simulation of compressible flow in a convergent divergent nozzle

[@elhassenaliomer2191]

Hi ... How thrust can be calculated by such simulation?

[@kgengineeringsolutions]

Hi, unfortunately I do not know

[@clementb1951]

Hi, if you want to get the thrust I recommend you to do a 3d simulation of the nozzle. You set your pressure or mass flow initial consitions (you can only do a half of the nozzle and apply a symmetry).
Then on fluent you have in the configuration tab : Solution > Report definition. Here right click and add a new force report and select force. Then choose the axis of this force and the surface where the force should be calculated (here it is the divergent of the nozzle for a rocket) You will have a good estimation of your thrust.
Or use massflowrate*EjectionSpeed (and normally + (Ejection pressure - Atmospheric pressure) * SurfaceAreaExit
This formula gives you a good estimation.
To get the ejection speed you can refer to the Isentropic flow chart that gives you the mach at the exit for a given pressure differential.
Have a nice day

[@travisjude2450]

Hi, should not the NPR be 6 here. How come it is 7?

[@kgengineeringsolutions]

Hi, the absolute pressure is 7 bar and the outlet pressure is 1 bar=>the ratio is 7

[@정해찬-v1l]

@@kgengineeringsolutionshi but you didn’t put outlet pression as 1 bar isn’t it ?

[@kgengineeringsolutions]

@@정해찬-v1l Hi, the gauge pressure in outlet is 0 bar, see 13:25

[@elhassenaliomer2191]

Hello .... How the NPR can be changed ?

[@kgengineeringsolutions]

By changing the pressures

[@METUSHARTAMHANE]

According to paper corrount no is to be 5 so why you selected 0.5

[@kgengineeringsolutions]

With the courant number of 5, the simulation was not stable (I think the authors made a typo). Did you get a stable simulation with c=5?