Week 4: Project - Transient simulation of flow over a throttle body

Title: Transient simulation of flow over a throttle body

Objective: 1.Make case Setup for Transient state

2. Observe the pressure, mass flow rate, velocity & total cell count

3. Post process the result in PARAVIEW

Theory: In this challenge bend pipe taken inside it throttle plate is present for vary the mass flow rate. in this case Transient state solver taken due to turbulent flow of air . throttle plate is vary by given the rotating centre & rotating axis. so, observe pressure, mass flow rate, velocity & total cell count.

Case setup

1. Fluid used -Air

2. Solver- Transient state & Density based, Full Hydrodynamic & No hydrodynamic

3. end time -0.01ms

4. Intial & minimum step =1e-9

5. Maximum time step= 1

6. Inlet pressure= 150000pa

7.outlet pressure=100000pa

7. Base Grid size = 2e-3 m

8. Fixed embedding : scale>3 & layer >2

9. Turbulence model: RNG K-E

Boundry ID & Name

Throttle plate is vary

throttle plate is vary by the rotating centre & rotate about

Simulation time

Calculation end time for transient-state

Consider, Charact. length in x-direction =0.2m

flow through time= 0.2/100m/s

100m/s =Avg. velocity from steady state

flow through time=0.002

So, consider end time is more than the 4 to 5 times

end time=0.01sec

Output files

Fixed embedding

for observe the pressure & velocity around a throttle plate there is need to refine the mesh. so, that there is use of fixed embedding.

Fixed embedding= (base grid size)/2^n

base grid size uses =0.002m

n=3= scale

Embed layer =2

fixed embedding= 0.002/2^3

= 0.00025 m cell size is present for 2 layer after that there is base mesh size is present

Mesh

As throttle plate is rotating, so initially check the simulation mode is No-hydrodynamic . in this no hydrodynamic equation is not solved only mesh is check.

No hydrodyamic Mesh Animation

As throttle plate is rotating, so initially check the simulation mode is No-hydrodynamic . in this no hydrodynamic equation is not solved only mesh is check.

Velocity contour

from below plot of velocity contour We can see that as throttle plate is rotating on back side velocity is zero

Pressure contour

from below plot of Pressure contour We can see that as throttle plate is rotating on front side pressure is higher & on back side the pressure is zero

Velocity Animation

Pressure animation

Stream tracer animation

1. Mass flow rate

from the below plot we can verify that conitnuity equation which states that INFLOW=OUTFLOW mass flow rate

2. Avg. Velocity(m/s)

from below plot we can see that inlet velocity is 100m/s but outlet velocity is higher its around 150m/s its because of reduction of total pressure at outlet

3.Total pressure

Total pressure =static pressure + Dynamic pressure . at outlet total pressure is decreases which means that velocity is increases on outlet its becasue of the when air passes from small cross-section area velocity increases & pressure reduction

4. Static Pressure

from below plot we can see that inlet static pressure is higher , while outlet static pressure is constant 1pa

5. Total cell

Total cell around 40000 its increases due to refine mesh around throttle plate

Overall conclusion

1. Fixed embedding helps for refine the mesh around the boundry of throttle plate, which helps for capture the correct velocity & preesure around throttle plate.

2. On front side of throttle plate higher pressure because air strike but on back side lower pressure generated due to the boundry sepration of layer , Static pressure is decreasses & velocity is zero.

3. Velocity is decrease on front side of the throttle plate but after that velocity increases because decrease in total pressure.

4. simulation mode is No-hydrodynamic is best option for rotataing parts because its check mesh only not solve any equation