Modelling and simulation of flow through a Flowbench - CFD using SolidWorks

ABSTRACT

In this Project, Creating a 3D model of a flowbench and run flow analysis where the internal flow takes place and running a baseline simulation and then performing a grid dependency test(4, 5 & 6) at a particular valve lift(0.003) and also performing valve lift(0.001 -0.008) test at a particular grid size(5). Study the velocity and pressure plots and explain the results. Comparing the results and plotting the valve lift vs mass flow rate.

Geometry of the Flow-Bench

Dimensions of the Valve Lift

Parameters;

Internal Fluid Flow

Total Pressure: 401325 Pa

Static Pressure: 101325 pa

Baseline Grid Size: 3

Valve Lift: 0.003 m

[BaseLine Simulation]

Output

Velocity Plot;

Pressure Plot;

Mass-Flow Rate;

GRID DEPENDENCY TEST

Parameters for Grid dependence test

New parametric study- Grid dependence test

In order to select the level of refinement, we run a parametric test where for constant valve lift of 0.003 m we set three different grid sizes ranging from 4 to 6. Also, we check the Velocity and Pressure plots for these three values.

Note: Level of refinement of these plots is 255.

Output [Valve Lift @ 0.003 m]

Grid - 4

Velocity Plot;

Pressure Plot;

Grid - 5

Velocity Plot;

Pressure Plot;

Grid - 6

Velocity Plot;

Pressure Plot;

SG Mass-Flow Rate

Results and Observation

1. From the graph, we can see that as the refinement level increases mass flow rate magnitude also get more optimum.
2. There are no subsequent changes in pressure plots.
3. But in the Velocity plot, when the fluid enters the combustion chamber for different grid sizes the velocity pattern is considerably changing.
4. With the grid size of 5, we observe a pattern that can be said to be the Swirl of the fluid that happens inside the cylinder. Hence for proper results and plot description, we go with grid size 5. Although, we may go for a higher value but that may increase the computation time as well.

VALVE LIFT TEST

Parameters for Valve Lift Test

With a grid size of 5, now we run another parametric study where we change the valve lift from 0.001m to 0.008m with 8 intervals, rest other parameters are kept same one change that is made is we add a local mesh around the valve so as to get better results. In this study we\'re looking for the Velocity and Pressure plots, Mass flow rates for different valve lifts, Flow trajectories, etc.

Valve Lift @ 0.001 m

Velocity Plot;

Pressure Plot;

Velocity Trajectory;

Valve Lift @ 0.002 m

Velocity Plot;

Pressure Plot;

Velocity Trajectory;

Valve Lift @ 0.003 m

Velocity Plot;

Pressure Plot;

Velocity Trajectory;

Valve Lift @ 0.004 m

Velocity Plot;

Pressure Plot;

Velocity Trajectory;

Valve Lift @ 0.005 m

Velocity Plot;

Pressure Plot;

Velocity Trajectory;

Valve Lift @ 0.006 m

Velocity Plot;

Pressure Plot;

Velocity Trajectory;

Valve Lift @ 0.007 m

Velocity Plot;

Pressure Plot;

Velocity Trajectory;

Valve Lift @ 0.008 m

Velocity Plot;

Pressure Plot;

Velocity Trajectory;

Graph:

Mass-Flow Rate;

OBSERVATION

1. From The pressure plot, we can observe that as the valve lift increase the pressure decreases due to the increase in distance between the valve opening and the cylinder.
2. From the velocity plot, we can observe that as the valve lift increase the velocity increases and the pressure decreases. Pressure is maximum at the valve lift 0.001 and from the velocity trajectory, it is observed that due to high-pressure swirling effect takes place.
3. The swirling effect reduces as the valve lift increases can be observed in the velocity trajectory plots.
4. Mass flow rate reduces as the valve lift increases this is because of the resistance to the flow due the attachment to the valve seat and valve head. As the valve lift continue to increase, larger intake valve opening allows for greater induction mass flow rate which causes the increase of discharge coefficient.