Modelling and simulation of flow through a flowbench
Aim: Internal Flow analysis of Flow Bench Geometry using Solidworks Flow Simulation
To Calculate the Grid Dependency Test
To Calculate the graph of Mass Flow rate vs. Valve Lift
Theory: An air 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. 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.
Model:
Grid Dependency Test
We will perform simulation at different level from 3 to 5 and putting the local mesh refinement at 2 constants for all the three process. We can see that as we refine the mesh the results will be seen more precise and the error is reduced.
The grid dependency test was performed from 0.002m-0.008m using the 6 divisions value of range.The difference in result can be seen from the graph and table.
Procedure:
- In this problem we will first open Solidworks part modelling to make our part for the Flow Simulation in Solidworks using Flow Simulation.
- We will now go to Top Plane and then draw a circle of diameter 120mm and then we will extrude it to 100mm and the direction would be on the opposite side.
- Now, we will select the Front Plane and then we will make a straight vertical line on the origin of 120mm and then a horizontal line of 120mm and then we will apply a fillet of radius 50mm and then we will exit the sketch.
- Now we will go to reference geometry and then click on the horizontal line and then on the point of horizontal line. This will make a plane on the front point of the horizontal line where we will be making the circle.
- Now we will go to the plane 1 and then sketch and then we will make a circle of diameter of 50mm and then we will use sweep tool using the circle as the sketch and the curve as the path.
- Now we will create the valve and for this we will first create an axis so that it would help us to create the valve.
- We will go to reference geometry and then for axis we will select the down face of the sweep path and then we will select the face and it will create an axis on the centre.
- Now we will go in the reference geometry and then select the plane and then reference 1 as the axis and reference 2 as the Front Plane.
- Now that will create our Plane 2 where we will be sketching our valve of the upper face as 10mm diameter and lower face as the 40mm diameter and the angle we can select of our own as it is a made up geometry for the analysis. Now we will use revolve boss/base to revolve using the axis.
- Now our part modelling is done we will go for Flow simulation and at first we will create Lids on the sweep face and the lower face of the cylinder.
- Now we will go to wizard option and then we will be selecting the internal flow option and the fluid to be air and velocity to be 200m/s.
- Now we will use the Boundary condition to create the boundary and we will create a boundary on the sweep face and we will give a total pressure of 401325Pa and for the lower face of the cylinder we will use a static pressure of 101325Pa.
- Now we will create cut plots of velocity and pressure and use the option of global maxima and global minima.
- For the global goal we will create a Global Goal mass low rate and for the Surface goal we will use the mass flow rate and then lower face.
- Now we will click on the valve face and then edit sketch and then we will go into parametric study using the valve lift as the input dimension and then we will go for output parameter as the goals and the cut plot.
- Now we will go to the global mesh and then we will select the advanced channel refinement and then we will increase one by one from 3 to 6.
- We will also be using local mesh and then face of the valve which are inside and then refining cells to be 3.
- Now we will run the solution and we will be getting the valve lift from 0.002m-0.008m.
- We will get mass flow rate for all the cases and we have to do it increasing refinement case by case and then we will get the grid dependency.
Global Mesh Setting:
Local Mesh Setting:
Results and Plots:
Grid Size: 3
Pressure Contour
Pressure (Design Point 1): 0.002m
Pressure (Design Point 2): 0.0032m
Pressure (Design Point 3): 0.0044m
Pressure (Design Point 4): 0.0056m
Pressure (Design Point 5): 0.0068m
Pressure (Design Point 6): 0.008m
Velocity Contour
Velocity (Design Point 1): 0.002m
Velocity (Design Point 2): 0.0032m
Velocity (Design Point 3): 0.0044m
Velocity (Design Point 4): 0.0056m
Velocity (Design Point 5): 0.0068m
Velocity (Design Point 6): 0.008m
Goal Data
Pressure Data
Velocity Data
Valve Lift vs. Mass Flow Rate
Grid Size: 4
Pressure Contour
Pressure (Design Point 1): 0.002m
Pressure (Design Point 2): 0.0032m
Pressure (Design Point 3): 0.0044m
Pressure (Design Point 4): 0.0056m
Pressure (Design Point 5): 0.0068m
Pressure (Design Point 6): 0.008m
Velocity Contour
Velocity (Design Point 1): 0.002m
Velocity (Design Point 2): 0.0032m
Velocity (Design Point 3): 0.0044m
Velocity (Design Point 4): 0.0056m
Velocity (Design Point 5): 0.0068m
Velocity (Design Point 6): 0.008m
Goal Data
Pressure Data
Velocity Data
Valve Lift vs. Mass Flow Rate
Grid Size: 5
Pressure Contour
Pressure (Design Point 1): 0.002m
Pressure (Design Point 2): 0.0032m
Pressure (Design Point 3): 0.0044m
Pressure (Design Point 4): 0.0056m
Pressure (Design Point 5): 0.0068m
Pressure (Design Point 6): 0.008m
Velocity Contour
Velocity (Design Point 1): 0.002m
Velocity (Design Point 2): 0.0032m
Velocity (Design Point 3): 0.0044m
Velocity (Design Point 4): 0.0056m
Velocity (Design Point 5): 0.0068m
Velocity (Design Point 6): 0.008m
Goal Data
Pressure Data
Velocity Data
Valve Lift vs. Mass Flow Rate
Conclusion:
Grid dependency Test
We can conclude from the above plots that the grid size with 5 is giving better results than the other two. Hence, it can be chosen as the standard mesh for the parametric study in this case.
Mesh refinement essentially divides the existing elements in half. As a result, mesh refinement operations approximately double the number of line elements, quadruple the number of area elements, and increase the number of volume elements by a factor of eight. Hence, it would result in a better result up to some extent because we have to take care of the other factors also.
Velocity Contour
As we can see that the valve opens at the place at different lifts hence there is increase in velocity along with increase in mass flow rate and also at low valve lift the area near the openings will create vortices due to sudden contraction in area.
Pressure Contour
When the valve is closed there is maximum pressure inside the cylinder but when the valve opens the pressure drops suddenly and that is the thing we have to take care of when designing a flow bench because high pressure drop can lead to increase in work input.
Valve Lift vs. Mass Flow Rate
We can clearly see from the plot that with increase in valve lift mass flow rate increases.