Objective

To simulate flow through a mixing tee for various cases

• Case 1 (60 points)
  • Short mixing tee with hot inlet velocity of 3m/s
  • Momentum ratio of 2
• Case 2 (60 points)
  • Long mixing tee with hot inlet velocity of 3m/s
  • Momentum ratio of 2
• Case 3 (60 points)
  • Short mixing with hot inlet velocity of 3 m/s
  • Momentum ration of 4

Introduction

A Mixing tee is used to mix two fluids with variable temperatures or composition, in order to get a proper mixing of fluids the velocity of cold fluid can be increased. To know how well the fluid is mixed we could find the Standard deviation, if the SD is less then the fluid is mixed properly.

Mesh

For Short Mixing tee

For Long Mixing tee

Mesh Quality Report

For Short Mixing tee

For Long Mixing tee

Selected models to run simualtion

Energy (To consider heat equation)

Fliud - air

B.C

Inlet hot - velocity inlet (input 3m/s)

Inlet cold - velocity inlet (varying according to different cases)

Outlet - Pressure outlet

Walls - walls

Type of flow - Turbulent

Selected realizable k-epsilon

Case 1

Short mixing tee with hot inlet velocity of 3m/s & Momentum ratio of 2

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

Velocity of cold inlet = 6 m/s

Case 2

Long mixing tee with hot inlet velocity of 3m/s & Momentum ratio of 2

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

Velocity of cold inlet = 6 m/s

Case 3

Short mixing tee with hot inlet velocity of 3m/s & Momentum ratio of 4

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

Velocity of cold inlet = 12 m/s

Plots

Case 1

Residuals

Average outlet temperature

Standard deviation of temperature

Case 2

Residuals

Average outlet temperature

Standard deviation of temperature

Case 3

Residuals

Average outlet temperature

Standard deviation of temperature

Contour plots of velocity & temperature

Case 1

Temperature plot

Velocity Plot

Case 2

Temperature plot

Velocity Plot

Case 3

Temperature plot

Velocity Plot

Table ofCell countAverage, outlet temperature & Number of iterations for convergence

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Conclusion

This simulation was done to find the mixed efficiency of two fluids in which one fluid enters the tee having a temperature of 300k and other fluid 283 k, we ran three simulations two short mixing tee with different cold fluid velocity and one with long tee. By observing the above table the short tee with increased cold fluid velocity of 12 m/s is having high mixing efficiency than the other two tee's. Therefore even by increasing the lenth of the pipe the outlet temperature remains the same as the original pipe.