Week 1- Mixing Tee

Aim:In this challenge, we have two versions of the mixing tee. One of them is longer than the other.

our job is to set up steady-state simulations to compare the mixing effectiveness when hot inlet temperature is 36⁰C & the Cold inlet is at 19⁰C.

Use the k-epsilon and k-omega SST model for the first case and based on your judgment use the more suitable model for further cases. Giving the reason for choosing a suitable model is compulsory.

1. Case 1
   • Short mixing tee with a hot inlet velocity of 3m/s.
   • Momentum ratio of 2, 4.
2. Case 2
   • Long mixing tee with a hot inlet velocity of 3m/s.
   • Momentum ratio of 2, 4.

Momentum ratio = velocity at cold inlet / velocity at hot inlet

Theory:

Mixing tee: mixing tee is a flwo control device, in which it contain two inputs and one output, the main function of this mixing tee is mixing the two different flows with each other.

steps invalue in the mixing tee shown below:

• geometry
• meshing
• setup
• solution
• result

analysing the mixing tee flow for short arm

case 1:

• Short mixing tee with a hot inlet velocity of 3m/s.
• Momentum ratio of 2
• hot inlet temperature is 36⁰C
• the Cold inlet is at 19⁰C.
• cold inlet velocity of 6m/s.

1) Geometry:

• importing the geometry: we have to import the geometry into the ansys workbench

• extracting valume:

• supresing physics: this comand is used to hide the solid part of the model.

2)Meshing:Meshing is nothing but the deviding the model into small peices and the distance between the points is 0.002.

number of node :21391

number of elements:106249.

afetr the complesion of meshing we have to give the names for each and every face

Element matrix:

3) setup:

• Domain: 1) steday state

2) presure based solver

• materieal : 1) Air-fluid

2)alluminium

• model: k-epsilon>reliabel>standard wall function
• cell zone: air-fluid-valume
• boundry conditions: 1) hot inlet velocity of 3m/s.

2)cold inlet velocity of 6m/s.

• initialing: 1)hybridinitializing

solutions:

Residual: for 250 iterations

Tempreture output:

Presure output

case 2:

• Short mixing tee with a hot inlet velocity of 3m/s.
• Momentum ratio of 2
• hot inlet temperature is 36⁰C
• the Cold inlet is at 19⁰C.
• cold inlet velocity of 12m/s

1) geometry: same as above

2)meshing: meshing is also same as above

3) setup:

• Domain: 1) steday state

2) presure based solver

• materieal : 1) Air-fluid

2)alluminium

• model: k-epsilon>reliabel>standard wall function
• cell zone: air-fluid-valume
• boundry conditions: 1) hot inlet velocity of 3m/s.

2)cold inlet velocity of 12m/s.

• initialing: 1)hybridinitializing

solutions:

Residual: for 250 iterations

Tempreture:

presure:

analysing the mixing tee flow for long arm

case 2:

• Short mixing tee with a hot inlet velocity of 3m/s.
• Momentum ratio of 2
• hot inlet temperature is 36⁰C
• the Cold inlet is at 19⁰C.
• cold inlet velocity of 6m/s.

1) Geometry:

• importing the geometry: we have to import the geometry into the ansys workbench

• extracting valume:

• supresing physics: this comand is used to hide the solid part of the model.

2)Meshing:Meshing is nothing but the deviding the model into small peices and the distance between the points is 0.002.

number of node :28495

number of elements:141303

afetr the complesion of meshing we have to give the names for each and every face

Element matrix:

3) setup:

• Domain: 1) steday state

2) presure based solver

• materieal : 1) Air-fluid

2)alluminium

• model: k-epsilon>reliabel>standard wall function
• cell zone: air-fluid-valume
• boundry conditions: 1) hot inlet velocity of 3m/s.

2)cold inlet velocity of 6m/s.

• initialing: 1)hybridinitializing

solutions:

Residual: for 250 iterations

tempreture:

presure:

case 2:

• Short mixing tee with a hot inlet velocity of 3m/s.
• Momentum ratio of 2
• hot inlet temperature is 36⁰C
• the Cold inlet is at 19⁰C.
• cold inlet velocity of 12m/s

1) geometry: same as above

2)meshing: meshing is also same as above

3) setup:

• Domain: 1) steday state

2) presure based solver

• materieal : 1) Air-fluid

2)alluminium

• model: k-epsilon>reliabel>standard wall function
• cell zone: air-fluid-valume
• boundry conditions: 1) hot inlet velocity of 3m/s.

2)cold inlet velocity of 12m/s.

• initialing: 1)hybridinitializing

solutions:

Residual: for 250 iterations

tempreture:

presure:

Conclusion: when we are doing short arm length analysis in that first condition we have momentom ration 1:2 it means that here the velocity of the mixing the flows are very less so here it give less efficiency but when we compare the same case with the long arm then the efficiency of short arm is less then the long arm.similarly when increase the momentum ration by 1:4 at that time the velocity of the mixing of both flows are very heigh so it will give more efficiency. at the end if we increase the velocity at cold inlet the efficiency is more.