Week 1- Mixing Tee

AIM: To carry out simulation of mixing of air at different temperature and velocity in Tee pipe using Ansys CFD.

INTRODUCTION

In this study,mixing of air at diffferent temperatures & velocity are studied in two types of TEE  joint pipes.

1.  SHOR TEE.

2. LONG TEE.

Here, the outlet temperature of the air mixture is investigated at different velocities in both TEE pipes and their results are compared  with each other.The study of mixing tee is highly important in piping designing because, when two fluid streams of different temperatures are mixing with each other there are thermal fluctuation taking place.This fluctuation leads to a phenomena called as thermal fatigue in pipes.In this condition the pipes undergoes thermal stripping.

THERMAL STRIPPING : Phenomena of inducing fatigue loading in the pipe structure due to the fluctuation of temperature during mixing of fluids with different temperatures causing fatigue failure of pipe is  called as thermal stripping.

With the  help of CFD simulation we can avoid the thermal stripping process in the piping structure.

RESULTS :

From the above investigation some results could be concluded.

1. Average output air temp : 

In short tee= 31  deg celcius- momentum ratio=2- k epsillon

                 = 28.5 deg celcius - momentum ratio= 4 - k epsillon 

                 = 31 deg celcius - momentum ratio= 2- k omega     

Cell count = 2840 nodes      

               = 12780 elements

In long tee = 31  deg celcius- momentum ratio=2- k epsillon

                 = 28.5  deg celcius- momentum ratio=2- k epsillon

Cell count= 3479 nodes

              =152727 elements

Also the oulet temperature is calculated using analytical method using the mathematical equation.

The temperature at outlet for both short and long tee is same T= 31.9 degree celcius

CONCLUSION :

1. Temperature at oulet decreases with the increase in the momentum ratio.

Reason:

The reason for the first conclusion is with the increase in the momentum ratio mixing of the air streams takes place properly.

2. Temperature at outlet is more close to the formulla method in long tee

3. Temperature at outlet is almost same for both short & long tee when momentum ratio is constant