Challenge

Week 9- Unsteady moving zones Approach

Aim: To simulate the motion of blades in a generic turbomachinery component using Steady & Unsteady approach.

Simulation setup:

Initially we have three zone mesh files, so first we will read one file and then append the other two file in fluent.
File >> read the mesh file >> mesh model will be displayed.

Domain >> Zones >> Append >> Case file select the mesh file >> Ok. Similarly select the other file as well.

From display check the different boundaries, surfaces and their names mentioned in display tab. Which would be very useful in later part while assigning the boundary conditions.

Moving Reference Frame Method:

Moving reference frame method is used for steady state simulation only.
Viscous Model >> K Epsilon, Realizable, Enhanced wall treatment.
Material: Air.
Zone:
- Fixed Farme: Fluid Type
- Rotating Frame: Fluid Type >> Edit >> Frame motion >> speed: 300rpm

Interface: (Select the interface which is overlapping)
- Interface 1: Create >> Select Domain 1 interface & Rotating domain inner
- Interface 2: Create >> Select frame 3 inner & Rotating domain outer

Moving Mesh Motion Method:

All other setting other than those mentioned below remain the same as of moving reference frame method.
Physics >> General setting >> Pressure based >> 2D >> Transient state simulation.
Zone:
- Rotating Frame: Fluid Type >> Edit >> Mesh motion >> speed: 300rpm

Time step calculation:

Rotational velocity= 300rpm

Time Period = 60/N = `60/300=0.2sec`

we want to simulate the flow for one revolution of impeller. We want to acheive this time period in 1000 iteration so time step size will be,

Time step size `Deltat=0.2/1000=0.0002sec`

for accurate result the value of time step size should be less then 0.0002s

Reference Compute from Inlet, Hybrid Initialization.
Report Definition >> New >> Surface Report >> Mass Flow rate >> Outlet
Uncheck the residual convergence criteria, and also enable mass flow rate as the convergence criteria

Result:

Parameters	Moving Reference Frame method	Moving Mesh Motion Method
Residual
Velocity contour
Static Pressure
Total Pressure
Mass Flow Rate at Outlet
Mass Flow Rate
Velocity Plot
Static Pressure Plot
Total Pressure Plot

Transisent Flow Animation:

Conclusion:

From analysising both the methods it is found that the transisent simulation after few time flow will result in steady state.
Currently, we have simulated the transient simulation for 0.2s i.e for one revolution of impeller. For industrial problems it is usually simulated for 5-6 revolutions, but due to resource constraint we have limited our study.

Ship work like this
in your own course.