## Fluids

#### Graph plot between Pressure ratio and constant span

• Sushil Chaudhary
Subscriber
Does anyone have an idea how to calculate the inlet and outlet pressure at constant span (Lets say at 0.2,0.4,0.6,0.8,1.0)?
If I am able to calculate the inlet and outlet pressure at given span then I will be able to calculate the pressure ratio and plot the graph between pressure ratio and normalized span. Please help me out.
CFD analysis of axial flow compressor
I'm using ANSYS CFX - CFD POST
Here is the picture of graph for reference
• C N
Ansys Employee

Hello,

I recommend you to follow the best practices method to simulate the axial flow compressor with this tutorial. In this tutorial you can understand how to set up the boundary conditions appropriately in order to calculate the pressure profiles and also the video link to understand about the physics.

Chapter 23: Aerodynamic and Structural Performance of a Centrifugal Compressor (ansys.com)

(1) ANSYS CFX: Simplified Compressor Design and Evaluation using Turbo Setup - YouTube

Convergence tips and a approach to solve the problem according to best practice .

When only a poor initial guess is available, it may be helpful to first run with a specified mass flow inlet and a static pressure outlet. The outlet pressure in this case is fairly arbitrary and is usually set at, or close to zero to reduce round-off error. The specification of a mass flow inlet may be more robust. However, a mass flow inlet assumes a uniform inlet velocity—which may not be appropriate. Once the overall flow is established, the boundary conditions may then be changed to total pressure at the inlet and mass flow at the outlet.This way you can calculate the pressure accurately.

I hope this was helpful to you in your simulation .

Thanks,

Chaitanya Natraj