Modelling and simulation of flow through a flowbench

OBEJCTIVE:

• To create a 3D model of a flow bench and to run flow analysis
• Grid dependence test
• For three grids run your simulation at a particular valve lift and explain your results
• Effect of valve lift on mass flow rate
• once best grid is decided, run a parametric sweep to show the effect of valve lift on mass flow rate

FLOW BENCH DIMENSIONS

BORE DIAMETER: 50mm

LENGTH OF CYLINDER : 50mm

INTAKE MANIFOLD DIAMETER : 10mm

BOUNDARY CONDITIONS:

1. TOTAL PRESSURE : 101325 Pa

2. STATIC PRESSURE: 5325 Pa

PROCEDURE:

1) Create a cylinder with dimensions shown above then make the circular inlet port by sweeping circular profile.

2) Create axis at the bottom of the intake port then create plan over there and by using that plane create the valve.

3) Make the valve open at 1mm.

4) Save the profile and run the wizard by setting all the conditions.

5) Insert boundary conditions as Total inlet pressure as 401325 and Static pressure at the outlet as 101325.

6) Run the basic simulation then run parametric study by taking Global mesh as input to do the grid dependency test.

7) Constraint the valve in such a way so that the valve can only move to the vertical distance

8) Now run parametric study by taking Valve open distance as input.

9) Save and conclude the results.

RESULTS:

GRID DEPENDENCY TEST

Grid dependence test is also called as mesh dependence test, in the which the model is subjected to successive smaller cell sizes for calculations, that is the model is divided into a smaller number of parts called elements and calculations are made. As the element size decreases the error towards the results reduces. Now for the above 3D model, we run the simulation with 3 refining values. or a particular valve lift of 2mm.

GRID DEPENDENCY TEST AT 2MM VALVE LIFT:

CASE 1: VELOCITY PLOT AT GRID SIZE 3

CASE 2 : VELOCITY PLOT AT GRID SIZE 4

CASE 3 : VELOCITY PLOT AT GRID SIZE 5

Hence by grid dependency test, we concluded the following points

On increasing the level of grid we got more accurate and smoother looking profile.

According to my system's configuration automatic grid level 5 is the optimum case to perform the simulations.

Now we are increasing the valve lift from 0.001 to 0.01 m in order to see the effect on the mass flow rate.

valve lift at 0.001m

cut plot for velocity

cut plot for pressure

valve lift at 0.00325m

cut plot for velocity

cut plot for pressure

valve lift at 0.0055m

cut plot for velocity

cut plot for pressure

valve lift at 0.00775m

cut plot for velocity

cut plot pressure

FLOW TRAJECTORIES OF VELOCITY

RESLUTS:

TABLE AND GRAPH OF MASS FLOW RATE VS VALVE LIFT

OBSERVATION FROM THE ABOVE GRAPH

• Mass flow rate increases as the value of valve lift increases..
• We can see that mass flow rate is getting constant for higher valve lift.
• The negative value of mass flow rate signifies that mass is leaving the system.

CONCLUSION:

1. From the velocity plots, we saw as the valve lift increases the velocity of fluid also increases. Hence higher the valve lift higher will be the velocity of fluid.
2. From the pressure plot, we saw as the valve lift increases the pressure of the fluid decreases. Hence higher the valve lift lower will be the pressure of fluid.
3. Mass flow rate increases as the valve lift increases but for higher values of valve lift mass flow rate becomes constant. As we can track from the graph and table of mass flow rate vs valve lift that for 0.0055m and 0.00775m of valve lift we got almost the same value for mass flow rate which is 0.01 kg/s.
4. Higher the level of grid in the mesh more accurate will be the results.