Modelling and simulation of flow through a flowbench (Flow Simulation using Solidworks)

Aim: In this project, we create a 3D model of a flow bench and run flow analysis & perform the following operations:

• Grid dependence: For this test, we run the simulation for three different grids at a particular valve lift and compare results in order to decide which mesh level is more precise.

• Effect of valve lift on mass flow rate: Here we run a parametric sweep to show the effect of valve lift on mass flow rate for the selected grid level.

Definitions:

• Flow bench: It is a simple device to measure and quantify the amount of air flowing through the cylinder head runners and intake manifolds.
• Valve lift: It is the distance by which the valve is raised from its seated position when it is opened.

Dimensions:

• Cylinder diameter = 5 cm
• Length of the bore = 10 cm
• Inlet manifold diameter = 1.25 cm
• Shell thickness = 1.5 mm
• Lids were created at both ends of the flow-bench.

Procedure:

• A cylinder and valve are created with the given dimensions.
• Valve dimensions are constrained in order to move the valve vertically.
• Inlet total pressure(lid-1): 401325 pa & Outlet static pressure(lid-2): 101325 pa is given at both ends. This pressure difference helps the air to flow towards the lower pressure side.
• A study is made in order to observe the effect of grid-level on simulation results and the best grid level is chosen for further study.
• A parametric sweep is done for observing the effect of valve lift on the mass flow rate with the best-chosen grid level.
• Global and surface mass flow rates are taken as goals.
• Velocity and pressure cut plots are made for observation.
• Valve lift range: 2-6 mm and grid-level: 5 are chosen for the parametric study.

Results:

Grid dependency: Valve lift is taken as 0.004m    

Grid level: 3

Grid level: 4

Grid level: 5

By the observation the grid level 5 has fewer discontinuities and disturbances hence it is chosen for further studies. Even a high level of the grid can also be chosen for a much better result but it takes much long computation time.

Effect of valve lift on mass flow rate:

For this test, the valve lift is taken in the range from 2-6mm and grid level:5 is taken from the above observations.

Valve lift: 2mm

Valve lift: 3mm

Valve lift: 4mm

Valve lift: 5mm

Valve lift: 6mm

Conclusion: With the increment in valve lift the pressure drop decreases which is an advantage because lower the pressure drop much better the design of the port.

Obseravtions:

• From the pressure values, we can observe that as the valve lift increase the pressure decreases due to the increase in valve open flow area.
• From the velocity values, we can observe that as the valve lift increases the velocity increases.
• The swirling effect reduces as the valve lift increases can be observed in the velocity cut plots.
• Mass flow rate reduces as the valve lift increases this is because of the resistance to the flow due to the attachment to the valve seat and valve head.
• As the valve lift continues to increase, a larger intake valve opening allows for greater induction mass flow rate which causes the increase of discharge coefficient.