Reversed flow in inlet of aerospike nozzle

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  • Last Post 18 May 2020
maverick3761 posted this 13 May 2020

I'm trying to simulate aerospike nozzle at sea level. From my calculation, I should get ~2.71 exit Mach number but I get reversed flow in pressure inlet. When I use Roe-FDS, I get reversed flow in inlet after several thousands iteration.

Even if I leave the calculation(never converged), the flow doesnt even look like I expect it to be. Not even close.

I can't seem to attach my files. The loading is too long. So I insert it to external download link from WeTransfer instead.

Archieve of my workbench

 

General:

Density based

Axisymmetric

 

Models:

Energy

Inviscid

 

Material:

Air

-Ideal gas

-Cp 1006.43 J/kg k

-Molecular weight constant 28.966 kg/kmol

 

Boundary condition

Inlet

-Gauge total pressure 1500000 Pa

-Supersonic gauge pressure 1499999 Pa

-Total temp 900 K

 

Outlet

-Gauge pressure 101325

-Total temp 288 K

 

Methods

Formulation:Implicit

Flux type: AUSM

-Least squares cell based

-2nd order upwind

 

Control:

CFL: 3

 

The rest is left at default.

 

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rahkumar posted this 13 May 2020

Hello, 

According to your problem specification, what should be your inlet condition? 

Regards, Rahul

maverick3761 posted this 13 May 2020

I initialised it using the inlet.

Pressure at inlet is 1.5Mpa and temperature is 900K

rahkumar posted this 13 May 2020

Then please check your input conditions. You have entered total temperature as 900K. 

Regards, Rahul

maverick3761 posted this 14 May 2020

Is it supposed to be different than my design parameter? Ansys user guide state that  Total Temperature   sets the total temperature of the inflow stream. 900K is the temperature of my fluid in inlet.

rahkumar posted this 14 May 2020

Hello,

Please refer to the following link. It will give you an idea on how to set up the total pressure and temperature. 

https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v201/en/flu_ug/flu_ug_sec_bc_pinlet.html?q=total%20temperature

Regards, Rahul

maverick3761 posted this 16 May 2020

Hello,

I can't see my mistake. Maybe you could point it out? 

Your advise seem abit vague.

 

Thanks

rahkumar posted this 18 May 2020

Hello, 

When you mention 900 K is your inlet temperature, is it the static temperature or total temperature? Because the total temperature is a function of velocity and if you are entering total temperature at the inlet, the total temperature formula must be used. 

Regards, Rahul

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