Week 1- Mixing Tee

Aim :- 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.

OBJECTIVE:-

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.

PROCEDURE AND RESULTS:-

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

In case 1 we are doing two different sub-cases one being the velocity of cold air 6m/s and another being 12m/s

Geometry:-

Meshing:-

After creating the Mesh file, we name the geometry for the further use

1. Inlet x (inlet where the hot air come from)

2. Inlet y (inlet where the cold air come from)

3. The walls

4. Outlet

After updating the mesh file we go to the solution part.

Setup:-

for setup physics use energy models with k-epsilon,k-omega SST viscous model, boundry conditions for both models are same as-

momentum ratio 2

velocity inlet x = 3 m/s, temperature = 36c

velocity inlet y = 6 m/s, temperature = 19c

and for momentum ratio 4

velocity inlet x = 3 m/s, temperature = 36c

velocity inlet y = 12 m/s, temperature = 19c

k-epsilon:- ( when momentum ratio 2)

residuals plots

Area weighted average:-

temperature contour :-

velocity contour :-

K-omega SST :- (when MR 2)

Area weighted average at outlet:-

Temperature contour :-

Velocity contour :-

k-epsilon:- ( when momentum ratio 4):-

Area weighted average at outlet:-

Temperature contour:-

Velocity contour:-

case 2 :- mesh size 3 mm

for setup physics use energy models with k-epsilon, boundry conditions for-

momentum ratio 2

velocity inlet x = 3 m/s, temperature = 36c

velocity inlet y = 6 m/s, temperature = 19c

and for momentum ratio 4

velocity inlet x = 3 m/s, temperature = 36c

velocity inlet y = 12 m/s, temperature = 19c

k epsilon:- (when MR 2)

Area weighted average at outlet:-

Temperature contour :-

Velocity contour :-

K- epsilon:- (when MR 4)

Temperature contour_

Velocity contour :-

Conclusion:-

In both cases of K-epsilon snd k-omega, k-epsilon has better results as we see in the residual plot these converge faster compared to k-omega and as the length of the pipe increases the mixing has a lot of time and increases the temperature losing its main objective.