Week 1- Mixing Tee

Mixing Tee

Description:

Mixing tee is a flow control devices.It mixes the two different fluid stream into a combined fluid stream.In has two inlets and one outlet.In this two inlets, one is located along the X axis and the other is located along the Y axis.The outlet is located along the X axis.

Formula:

momentum ratio = velocity at cold inlet/velocity at hot inlet.

Steps in analysis of Mixing Tee:

• Geometry
• Meshing
• Set up
• Solution
• Result

Case 1: Shorter Mixing Tee

• Velocity at hot inlet =3 m/s
• Temperature at inlet=25C
• Temperature at cold inlet=10C
• Momentum ratio=2

Geometry:

1.Importing the model.

2.Fluid volume extraction.

3.Suppress for physics.

1.Importing the model:

The first step in this case is importing the solid Tee model to the space claim.

2.Fluid volume extraction:

Volume extraction is defined as extracting the volume phase from the solid geometry. Here the fluid volume is extracted by using the volume extraction command.

3.Suppress for physics:

Suppress for physics is a command it is used to deactivate the solid model.In this case we only requires the fluid volume so that the solid model is suppresed.

Meshing:

Meshing is the process of dividing the solid model into a small individual element.Here we are discretizing the solid model into a small element of size 0.003m.We obtained,

No of elements = 39393.

No of nodes = 8275.

After completion of meshing naming should be done. Proper naming should be given for all the faces and the quality of the each element is checked.

Element Metrics

Set up:

This is the major step in analysis because here only we gave the values and conditions of the Tee model.This case runs under the following condition,

General :1.Steady state

2.Pressure based solver

Material :1.Fluid-Air

2.Solid-Aluminium

Model :1.K epsilon -standard K epsilon-standard wall function

Cell zone condition :Volume-Fluid-Air

Boundary condition:1.Inlet X- Velocity inlet-3m/s

2.Inlet Y- Velocity inlet-6m/s

Initialization :Hybrid initialization

After intialization a plane has to be created normal to the Z axis. The temperature and velocity of the Tee is analysed in the plane and average temperature at the outlet is to be calculated.Finally the calculation is to be runned for 600 iterations.

Solution:

The calculation is converged in the 150 iterations.

Result:

Temperature Contour :

Case 1:Shorter Mixing Tee

• Velocity at hot inlet=3m/s
• Temperature at hot inlet=25C
• Temperature at cold inlet=10C
• Momentum ration=4

Geometry:

The shorter Tee model is imported.The fluid volume is extracted and the solid model is suppressed.

Meshing:

The solid Tee model is discretized into a small elements of size 0.003

No of elements = 39393.

No of nodes = 8275.

Element Metrics:

Set up:

General :1.Steady state

2.Pressure based solver

Material :1.Fluid-Air

2.Solid-Aluminium

Model :K epsilon-standard K epsilon-standard wall function

Cell zone condition :Volume-Air

Boundary Condition :1.Inlet X -velocity inlet-3m/s

2.Inlet y -velocity inlet-12m/s

Initialization :Hybrid initialization

Solution:

The calculation is converged in 150 iterations.

Result:

Temperature Contour:

Case 2: Long Mixing Tee

• Velocity at hot inlet= 3m/s
• Temperature at hot inlet=25C
• Temperature at cold inlet=10C
• Momentuem ratio=2

Geometry:

The long Tee model is imported in the space claim.The fluid volume is extracted and the solid model is suppressed.

Meshing:

The long Tee model is discretized into a small individual elements of size 0.003m.

No of elements:56269.

No of nodes :11664.

Element Metrics:

Set up:

General :1.Steady state

2.Pressure based solver

Material :1.Fluid-Air

2.Solid-Aluminium

Model :1.K epsilon-standard K epsilon-standard wall function

Cell zone condition :Volume-Fluid-Air

Boundary condition:1.Inlet X-velocity inlet-3m/s

2.Inlet Y-velocity inlet-6m/s

Initialization :Hybrid initialization

Solution:

The calculation is converged in 150 iterations.

Result:

Temperature Contour:

Case 2:long Mixing Tee

• Velocity at hot inlet=3m/s
• Temperature at hot inlet=25C
• Temperature at cold inlet=10C
• Momentum ration=4

Geometry:

The shorter Tee model is imported.The fluid volume is extracted and the solid model is suppressed.

Meshing:

The solid Tee model is discretized into a small elements of size 0.003

No of elements = 39393.

No of nodes = 8275.

Element Metrics:

Set up:

General :1.Steady state

2.Pressure based solver

Material :1.Fluid-Air

2.Solid-Aluminium

Model :K epsilon-standard K epsilon-standard wall function

Cell zone condition :Volume-Air

Boundary Condition :1.Inlet X -velocity inlet-3m/s

2.Inlet y -velocity inlet-12m/s

Initialization :Hybrid initialization

Solution:

The calculation is converged in 150 iterations.

Result:

Temperature Contour:

Conclusion:

In case 1 the momentum ratio is only 2 so that the ratio of the hot velocity and cold velocity is 1:2 due to this low velocity the fluid does not combine well so the efficiency in this case is very low.Similarly in case 2 also has the same momentum ratio but here the length differs so that the efficiency is quiet high when compared to the case 1.where as in case 3 the momentum ratio is high when compared to other two cases and the velocity ratio is 1:4 so that the velocity at cold inlet is four times the velocity of the hot inlet.Here the efficiency is directly proportional to the velocity at cold inlet.If the velocity at cold inlet increases the efficiency also increases.Here case 3 has high efficiency when compared to other two cases.