Modelling and simulation of flow through a flowbench

Aim :

To perform a flow bench simulation for different mesh grid size to select the best grid and check the velocity and pressure plots for every valve opening from minimum opening to maximum opening for mass flow rate.

OBJECTIVE:
• To perform a Grid dependence test.
• Simulating three grids at a particular valve lift.
• To perform the effect of valve lift on mass flow rate.
• Running a parametric sweep to show the effect of valve lift on mass flow rate.

Theory :

An airflow bench is a device used for testing the internal aerodynamic qualities of an engine component and is related to the more familiar wind tunnel.It is used primarily for testing the intake and exhaust ports of cylinder heads of internal combustion engines. It is also used to test the flow capabilities of any component such as air filters, carburetors, manifolds, or any other part that is required to flow gas. A flow bench is one of the primary tools of high-performance engine builders, and porting cylinder heads would be strictly hit or miss without it.A flow bench consists of an air pump of some sort, a metering element, pressure and temperature measuring instruments such as manometers, and various controls. The test piece is attached in series with the pump and measuring element and air is pumped through the whole system.

Modelling :

• To model, we need a cylinder an inlet pipe and a stopper or valve lifter
• a cylinder is created by extruding a circle having a center point of the circle on the origin point
• on the perpendicular plane we draw the pathline for the inlet pump and sketch the circle perpendicular to the sketch for the inlet pipe and using sweep command we create the inlet pipe
• now using the shell command we create the thick cylinder from the completely sold geometry
• for the stopper, we use the same perpendicular plane and sketch the cross-sectional geometry of the stopper and use revolve command it to form the stopper

After the profile is completed, now by entering the flow simulation tab and then running the wizard with the below conditions.

Input Conditions	Values
Analysis Type	Internal Flow
Fluids	Air
Units	SI units

Now simulating with insert boundary conditions as

Total Inlet Pressure	4*101325 = 405300
Static Pressure (outlet)	101325

• To perform the grid dependency test, run a parametric study by taking global mesh as input.
• The valve is constrained in such a way that the valve can move in a vertical motion.
• By taking the valve open distance as input, run a parametric study.
• Results are saved and plotted.

GRID DEPENDENCY TEST:

Considering the Valve Lift at 0.001m

CASE 1: Velocity plot in grid-level 4

CASE 2: Velocity plot in grid-level 5

CASE 3: Velocity plot in grid-level 7

CONCLUSION – GRID DEPENDENCY TEST:
In the above three cases, the results are getting smoother and accurate concerning an increase in the grid dependency levels. According to my system configuration, Optimum level to perform the flow simulation at a grid dependency level of 5.

RESULTS:
EFFECT OF VALVE LIFT ON MASS FLOW RATE:
To view the effect of the mass flow rate, increasing the valve lift from 0.001m to 0.008m by 7 equal intervals with global mesh level 5.

Valve Lift at 0.001m
Cut plot: Velocity contour

By default in Solidworks Simulation, the maximum stress value is set as the red value and the minimum stress is the blue value. The Velocity contour for the valve lift at 0.001m is shown above. The red colors of the plot represent what the stress value at that point in the model is. Here it is slightly low.

Cut plot: Pressure contour

The above plot pressure contour at 0.001m shows that the pressure inside the circular profile is extremely high at the start point up to the valve and slightly low at the valve point is due to the gap between the valve and cylinder is extremely less.

Valve Lift at 0.0021m
Cut plot: Velocity contour

The Velocity contour for valve lift at 0.0021m is shown above. By default in Solidworks Simulation, the maximum stress value is set as the red value and the minimum stress is the blue value. The red colors of the plot represent what the stress value at that point in the model is. Here it is a little bit high when compared to the valve lift at 0.001m.

Cut plot: Pressure contour

The above plot pressure contour at 0.0021m shows that the pressure inside the circular profile is higher at the start point up to valve entry point and less slightly low at the valve point is due to the gap between the valve and cylinder is low but when compared to valve lift at 0.001m the gap is slightly increased between them.

Valve Lift at 0.0033m
Cut plot: Velocity contour

The Velocity contour for valve lift at 0.0033m is shown above. By default in Solidworks Simulation, the maximum stress value is set as the red value and the minimum stress is the blue value. The red colors of the plot represent what the stress value at that point in the model is. Here it is a little high compared to 0.0021m valve lift.

Cut plot: Pressure contour

The above plot pressure contour at 0.0033m shows that the pressure inside the circular profile is slightly high at the start point up to the valve and slightly low at the valve point is due to the gap between the valve and cylinder is slightly low but when compared to valve lift at 0.0021m the gap is slightly increased between them.

Valve Lift at 0.0045m
Cut plot: Velocity contour

The Velocity contour for valve lift at 0.0045m is shown above. By default in Solidworks Simulation, the maximum stress value is set as the red value and the minimum stress is the blue value. The red colors of the plot represent what the stress value at that point in the model is. Here it is slightly high compared to the 0.0033m valve lift.

Cut plot: Pressure contour

The above plot pressure contour at 0.0045m shows that the pressure inside the circular profile is slightly high at the start point and slightly low at the valve point is due to the gap between the valve and cylinder is slightly low but when compared to valve lift at 0.0033m the gap is slightly increased between them.

Valve Lift at 0.0056m
Cut plot: Velocity contour

The Velocity contour for valve lift at 0.0056m is shown above. By default in Solidworks Simulation, the maximum stress value is set as the red value and the minimum stress is the blue value. The red colors of the plot represent what the stress value at that point in the model is. Here it is a little bit high when compared to the valve lift at 0.0045m.

Cut plot: Pressure contour

The above plot pressure contour at 0.0056m shows that the pressure inside the circular profile is slightly low due to the gap between the valve and cylinder is more when compared to the previous valve lift at 0.0045m.

Valve Lift at 0.0068m
Cut plot: Velocity contour

The Velocity contour for valve lift at 0.0068m is shown above. By default in Solidworks Simulation, the maximum stress value is set as the red value and the minimum stress is the blue value. The red colors of the plot represent what the stress value at that point in the model is. Here it is high when compared to the valve lift at 0.0056m.

Cut plot: Pressure contour

The above plot pressure contour at 0.0068m shows that the pressure inside the circular profile is slightly low due to the gap between the valve and cylinder is more when compared to the previous valve lift at 0.0056m.

Valve Lift at 0.008m
Cut plot: Velocity contour

The Velocity contour for valve lift at 0.008m is shown above. By default in Solidworks Simulation, the maximum stress value is set as the red value and the minimum stress is the blue value. The red colors of the plot represent what the stress value at that point in the model is. Here it is high when compared to the valve lift at 0.0068m.

Cut plot: Pressure contour

The above plot pressure contour at 0.008m shows that the pressure inside the circular profile is completely low due to the gap between the valve and cylinder is more when compared to the previous valve lift at 0.0068m.

FLOW TRAJECTORY:
Velocity contour:

The stress is shown as the red color that is high at the valve, this is due to the gap between them is low.

Pressure Contour:

The pressure contour of the Flow trajectory for the profile is shown above. The pressure is high before the valve this is due to the valve is at 0.001m distance, the small gap between the circular sweep profile and the cylinder makes the flow at high pressure.

GRAPH:
Here the graph is plotted between the valve lift vs mass flow rate from 0.001m to 0.008m. The mass flow rate for the respective valve lift is been provided below:
Valve Lift Mass Flow rate

Valve Lift	Mass Flow rate
0.001 m	0.0422
0.0021 m	0.0978
0.0033 m	0.1359
0.0045 m	0.1569
0.0056 m	0.1637
0.0068 m	0.1649
0.008 m	0.1652

SUMMARY FOR THE GOAL PLOTS:

Valve Lift vs Mass Flow rate:

The above graph shows that the increase in valve lift, the mass flow rate is getting increase with a constant value.

RESULTS EXPLANATION :
Grid Dependency Test:
The grid dependency test is taken to select and perform the optimum level of mesh for the mass flow rate in the profile geometry of the flow bench:

1. Initially, the grid dependency test is taken for level 4, level 5, & level7. On seeing the results of grid dependency, the value for level 7 shows an accurate and smoother value.
2. According to my computer performance, Optimum level for performing the simulation is taken at level 5 as because it is similar to the level 7 grid dependency level. Thus the level 5 is chosen for performing the flow simulation in flow bench geometry.

Mass Flow rate vs Valve lift:
Generally, Mass flow rate is the mass of a substance that passes per unit of time. From the graph, it is clear that as the value of valve lift increases, the mass flow rate increases this is due to the gap between the circular sweep profile and cylinder:

1. Initially, the valve lift is at 0.001m which shows that the gap is little that results in the high velocity at the valve lift point, and the pressure is heavy inside the circular profile. Hence the mass flow rate is low at this point.
2. As the valve lift value is increased from 0.001 to 0.0021m, the gap is increased that results in an increase in mass flow rate.
3. Similarly, as the valve lift is increased up to 0.008m, the mass flow rate is increased correspondingly.
4. At certain valve lift, the mass flow rate seems to be a constant valve. This is due to the gap between them provides enough space for the flow from a circular profile to the cylinder.

CONCLUSION :

1. As the valve lift increases, mass flow rate coming out of the outlet also increases simultaneously, as fluid rushes into the cylinder and exit from outlet.
2. From velocity cutplots, it can be concluded that as valve lift increases the velocity of fluid entering into the cylinder also increases and same thing can also be said for pressure cutplots. In addition to that it can be noted that as valve lift increases the flow trajectories of pressure and velocity became uneven, it may be due to sudden rushing of fluid into the cylinder causing it to have uneven pathlines.