[mertal1905]

Dear All,

I want to simulate flow in turbocharger compressor and compare with test results.

In tests, compressor inlet directly open to the atmosphere. There is no pressure measurement at the inlet.

Pressure and mass flow are being measured at the outlet. So, I have outlet total pressure value and mass flow rate.

What i want is to simulate the compressor in constant rpm with specified mass flow rate and calculate outlet total pressure.

How should i define boundary conditions? Inlet is open to atmosphere. So should I define 101325 Pa at inlet as static pressure or total pressure?

And also what about outlet bc? Mass flow outlet will work?

Thanks in advance

[DarylMusashi]

Dear Mertal,

I would recommend to define an inlet total pressure and a mass flow rate at the outlet. I know, you do not know the inlet total pressure, but you can calculate it easily with the values you have:

Assume that inlet mass flow [kg/s] = outlet mass flow [kg/s]. As you are doing CFD you certainly have the geometric values of your machine. In your CAD or CFD software please calculate the area A [m²] of the inlet patch. Finally you can assume the density of the air to be rho = 1.2 [kg/m³]

Consider the equation

mass flow = rho * A * velocity (Please rearrange this equation to calculate the velocity speed at the inlet.)

Finally please consider the relation between static and total pressure:

total pressure = static pressure + (rho/2 * (velocity speed at inlet)²)

Now you know all values to calculate the total pressure at the inlet (static pressure 101325 [Pa], rho = 1.2 [kg/s], velocity= [m/s]) and can set up the computation.

[mertal1905]

Originally Posted by DarylMusashi

Dear Mertal,

I would recommend to define a inlet total pressure at the inlet and a mass flow rate at the outlet. I know, you do not know the total inlet pressure, but you can calculate it easily with the values you have:

Assume that inlet mass flow [kg/s] = outlet mass flow [kg/s]. As you are doing CFD you certainly have the geometric values of your machine. In your CAD or CFD software please calculate the area A [m²] of the inlet patch. Finally you can assume the density of the air to be rho = 1.2 [kg/m³]

Consider the equation

mass flow = rho * A * velocity (Please rearrange this equation to calculate the velocity speed at the inlet.)

Please take note that you probably know the mass flow rate of the whole machine (from experimental data). Are you simulating just one passage instead of the whole machine? Then you need to divide the mass flow by the number of blade passages, of course.



Finally please consider the relation between static and total pressure:

total pressure = static pressure + (rho/2 * (velocity speed at inlet)²)

Now you know all values to calculate the total pressure at the inlet (static pressure 101325 [Pa], rho = 1.2 [kg/s], velocity= [m/s]) and can set up the computation.

Thank you very much Holger.

[shezi266]

hello mertal ,

iam also doing simulation on turbocharger compressor , so can you please tell me the details about this.
thanks