STEADY STATE ANALYSIS OF MIXING TEE

STEADY STATE ANALYSIS OF MIXING TEE

Case 1:

A steady state fluent analysis is carried analysis of a short mixing tee is done using ANSYS FLUENT. The fluid used is air. The hot air entering through inlet_x and cold air is entering through inlet_y. In this case, the hot air- temperature=25°C, velocity=3m/s. Cold air-temperature=10°C, velocity=6m/s.

Model

The model was imported in ANSYS DESIGN MODELLER.

The image of volume extract in ANSYS DESIGN MODELLER is shown below. Volume-179440 `mm^3`

Surface Area-23725 `mm^2`

Mesh

The model was meshed using ANSYS mesher with element size of 0.837 and a Patch Conforming method using terahedron was employed.

A mesh metric that identifies elements according to their quality was employed and it can be seen that the elements of lowest quality are minimal. Most of the elements have very high quality in the range of 0.6-1. Hence, the mesh is of acceptable quality. The meshed model is shown in image below.

Convergence

It takes 100 iterations for convergence. The residual plot is plotted in ANSYS FLUENT shown below

Result

Temperature plot on a cutplane along the middle of pipe in ANSYS CFD-Post.

The average output temperature is 19.913°C

Velocity plot on a cutplane along the middle of pipe in ANSYS CFD-Post.

The average output velocity is 4.5m/s

Case 2:

A steady state fluent simulation is carried analysis of a long mixing tee is done using ANSYS FLUENT. The fluid used is air. The hot air entering through inlet_x and cold air is entering through inlet_y. In this case, the hot air- temperature=25°C, velocity=3m/s. Cold air-temperature=10°C, velocity=6m/s.

Model

The model was imported in ANSYS DESIGN MODELLER.

The image of volume extract in ANSYS DESIGN MODELLER is shown below. Volume-264940 `mm^3`

Surface Area-100170 `mm^2`

Mesh

The model was meshed using ANSYS mesher with element size of 0.836 and a Patch Conforming method using terahedron was employed.

A mesh metric that identifies elements according to their quality was employed and it can be seen that the elements of lowest quality are minimal. Most of the elements have very high quality in the range of 0.6-1. Hence, the mesh is of acceptable quality. The meshed model is shown in image below.

Convergence

It takes 80 iterations for convergence. The residual plot is plotted in ANSYS FLUENT shown below.

Result

Temperature plot on a cutplane along the middle of pipe in ANSYS CFD-Post.

The average output temperature is 20.012°C

Velocity plot on a cutplane along the middle of pipe in ANSYS CFD-Post.

The average output velocity is 4.494m/s

Case 3

A steady state fluent simulation is carried analysis of a short mixing tee is done using ANSYS FLUENT. The fluid used is air. The hot air entering through inlet_x and cold air is entering through inlet_y. In this case, the hot air- temperature=25°C, velocity=3m/s. Cold air-temperature=10°C, velocity=12m/s.

Model

The model was imported in ANSYS DESIGN MODELLER.

The image of volume extract in ANSYS DESIGN MODELLER is shown below. Volume-179440 `mm^3`

Surface Area-23725 `mm^2`

Mesh

The model was meshed using ANSYS mesher with element size of 0.837 and a Patch Conforming method using terahedron was employed.

A mesh metric that identifies elements according to their quality was employed and it can be seen that the elements of lowest quality are minimal. Most of the elements have very high quality in the range of 0.6-1. Hence, the mesh is of acceptable quality. The meshed model is shown in image below.

Convergence

It takes 70 iterations for convergence. The residual plot is plotted in ANSYS FLUENT shown below.

Result

Temperature plot on a cutplane along the middle of pipe in ANSYS CFD-Post.

The average output temperature is 17.553°C

Velocity plot on a cutplane along the middle of pipe in ANSYS CFD-Post.

The average output velocity is 6.02m/s.

Case no.	Cell count	Average outlet temperature [°C]	Number of iterations for convergence
1	12530	19.913	100
2	15588	20.012	80
3	12530	17.553	70

Conclusion: From the above table, we can conclude that average temperature of case 3 has less output temperature than other two. The output temperature of case 1 is lower than case 2 so shorter the mixing tee better is mixing efficiency. The lowest temperature is in case 3 where shorter mixing tee is used with velocity of cold air more than other so, there is best mixing efficiency than other two cases.