Modelling and simulation of flow through a flowbench

AIM: To create a 3D model of flow bench and run flow analysis

OBJECTIVE:

• Create a 3D model of flowbench.
• Perform Grid dependence test to select the best gird.
• To run a parametric sweep to show the effect of valve lift on mass flow rate.

THEORY:

An air flow bench is a device used for testing the internal aerodynamics 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. Therefore, all the air passing through the metering element also passes through the test piece. Because the volume flow rate through the metering element is known and the flow through the test piece is the same, it is also known. The mass flow rate can be calculated using the known pressure and temperature data to calculate air densities, and multiplying by the volume flow rate.

3D MODEL:

• This model conatins a cylinder, inlet pipe and an valve lift.
• The cylinder is created by selecting the top plane and drawing a circle on it and then extruding it.
• Then for the inlet pipe we create a circle on the top surface of the cylinder and then in the front plane we draw a line profile with respect to the circle which will be the path to sweep the circle and then we use sweep tool to create the pipe.
• Then we select the shell tool to create a hollow path from inlet of pipe to cylinder.
• Then for the valve lift we select a plane with respect to the inlet pipe and then draw a profile of the valve lift such that it can be revolved and then after using the revolve tool we get the valve lift.

PROCEDURE:

• Firstly we create the 3D model of the flowbench.
• Then we add lids at the inlet of pipe and outlet of cylinder since we need a closed geometry to start with the flow stimulation.
• Then we start the flow stimulation wizard and give the required inputs like internal flow and air as fluid.
• Then we give the boundary conditions as total pressure of 2 bar at the end face of inlet port and static pressure of 1 bar at the lower face of cylinder.
• Then we go for the grid dependency test where we select three different level of mesh one after other and run the stimulation, to observe the results we select a velocity cut plot and the we come to a conclusion that the level of initial mesh - 5 gives the best results and we proceed the study with this settings.
• Then to see the effect of valve lift on mass flow rate we do a parametric study.
• For the study we select the goal of mass flow rate.
• Then in the parametric study for the input variables we give 7 points between 0.001m to 0.008m and for the output variable we select the goal of mass flow rate and the velocity cut plot and then we run the parametric study.

OUTPUTS:

• GRID DEPENDENCY TEST:

case 1: Mesh level 3

case 2: Mesh level 4

Case 3: Mesh level 5

So from the above grid test we came to a conclusion that the mesh level 5 gives the best results and we will proceed with this setting for the further study.

• VELOCITY PLOT:

1. Input variables :

2. Design data points:

3. At design point 1:

4. At design point 2:

5. At design point 3:

6. At design point 4:

7. At design point 5:

8. At design point 6:

9. At design point 7:

10 . Valve lift vs mass flow rate graph:

CONCLUSION:

• Higher the mesh levels the more better the results .
• As the valve lift increases the mass flow rate also increases, here negative values means the mass is leaving the systems with respect to the inlet condition.

DRIVE LINK:

https://drive.google.com/drive/u/2/folders/1EYRUkFCl2vp8XPKlymA3sYBTxezxthuY