Modelling and simulation of flow through a flowbench (SOLIDWORKS)
Modelling and simulation of flow through a flowbench
OBJECTIVES
The project aims to design a flow bench with an inlet valve and a port and the analysis is two-fold.
- Performance of a parametric test for the grid dependence of the analysis.
- Once the best grid is decided, analyzing the flow characteristics under various valve lifts with that grid.
2. THEORY
A flow 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.
Grid dependency test is the analysis of a model under the same conditions with different mesh refinement. This test obtains the ideal grid refinement number for the simulation.
3. INPUTS
- Cylinder dimensions:
- Bore diameter = 50 mm
- Length of cylinder = 100 mm
- Intake manifold diameter = 2 mm
- Shell thickness = 0.2mm
2. Boundary conditions:
- Inlet total pressure = 401325 Pa
- Outlet static pressure = 101325 Pa
3. Fluid:
- Fluid is Air.
- Flow is laminar & turbulent.
4. GEOMETRIC MODEL
- Flow bench
Cut view
- Valve
5. PROCEDURE
- Make the geometric model of flow bench.
- Create a project in flow simulation.
- Choose the fluid as air and flow as laminar & turbulent flow.
- Set outlet mass flow rate as goal and pressure & velocity cut plot.
- Run the initial simulation.
- Create a parametric study for grid dependency test. Four study is done for level of initial mesh 3 to 6.
- Compare the mass flow rate with mesh level. And choose the most accurate mesh for valve lift test.
- Then create a parametric study for valve lift. Eight study is done for valve lift 1 mm to 8 mm.
- Compare the mass flow rate with mesh level.
6. RESULTS
Grid dependency test (for valve lift = 4 mm)
- Mesh refinement size = 3
- Velocity contour
- Pressure contour
2. Mesh refinement size = 4
- Velocity contour
- Pressure contour
3. Mesh refinement size = 5
- Velocity contour
- Pressure contour
4. Mesh refinement size = 6
- Velocity contour
- Pressure contour
Results of parametric study –
From the above results, it can be seen that for the same inlet pressure, outlet pressure, wall condition and the valve lift of 4 mm the velocity variations in the cut plots are different. Thus we can say that the results greatly depend on the level of refining the fluid cells. In the above problem, we see that the refining value of the cells with 6 number has got a greater accuracy.
Mass flow rate vs mesh size -
As the refining of cells increases the mass flow rate at the outlet converges to more accurate value. So, the mesh of size 6 is chosen for the valve lift test.
Valve lift test (Mesh size = 6)
- Valve lift = 1 mm
- Velocity contour
- Pressure contour
- Valve lift = 2 mm
- Velocity contour
- Pressure contour
- Valve lift = 3 mm
- Velocity contour
- Pressure contour
- Valve lift = 4 mm
- Velocity contour
- Pressure contour
- Valve lift = 5 mm
- Velocity contour
- Pressure contour
- Valve lift = 6 mm
- Velocity contour
- Pressure contour
- Valve lift = 7 mm
- Velocity contour
- Pressure contour
- Valve lift = 8 mm
- Velocity contour
- Pressure contour
We know that the pressure in the inlet manifold is more than the static pressure at the outlet. Initially when the valve is closed pressure in the cylinder will be same as the static pressure at the outlet. When the valve lift position increases the pressure drop value reduces. Now since the pressure drop values decreases for the increase in valve lift between the inlet and the outlet, velocity of the gases flowing across the valve.
Mass flow rate vs Valve lift -
When the lift of the valve is small, pressure developing in the cylinder is at lower rate. And the pressure developing is high when the lift is larger. Initially, the pressure drop is high hence the tendency of the gases to flow from the region of higher to lower pressure is high. Hence we can say that the mass flow rate is more for a small lift in the valve position. And gradually decreases for higher values of the valve lift. This can be clearly seen in the above graph.
7. RESULTS
- With the increase of the mesh/grid size we get the more accurate results.
- Mass flow rate decreases with the increase of valve lift.
Google Drive Link - https://drive.google.com/drive/folders/1O-ptiO_-HuIa1JFHJoT-zjkJ2i17EAnF?usp=sharing