Simulation of Flow through a Flowbench

AIM

To simulate the Flow through a flow bench

OBJECTIVES

• To create a 3D model of a flow bench and run a flow analysis
• To perform a Grid dependency test for mesh levels 3,4 and 5 for Valve lift 1mm
• To run a parametric study to show the effect of Valve lift on Mass Flow Rate using the best grid

INTRODUCTION

Computational Fluid Dynamics or CFD is a technique that deals with the solution of fluid flow fields through numerical analysis. SOLIDWORKS Flow Simulation is a CFD software designed for the everyday SOLIDWORKS user and analyst. It provides dynamic feedback on the fluid flow and Thermal performance of their products. With Parametric optimization capabilities, users can automate the design and analysis process to discover the best iteration of their design within the familiar SOLIDWORKS environment.

An engine makes power by moving air and fuel into and out of it. The more of both it can move, and the faster it can do it, the more power the engine makes. In theory it’s pretty simple but in reality it’s more complicated. There are thousands of factors that effect not only how much air, but also the quality of that air, that gets into an engine. The most restrictive, and therefore the most critical factors, are the cylinder head intake and exhaust ports. That’s why so much thought and design must go into a cylinder head for each application. The flowbench is a tool that lets you check what that flow is.

THEORY

Geometry:

Cylinder dimension:

Bore diameter: 0.1m

Length of the cylinder: 0.1m

Intake manifold outer diameter: 0.025m

Thickness: 0.002m

Front View of the Flowbench

Flow bench:

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, carburettors, 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.

Usually, in the flow bench we take the port which is to be tested, however in this project we are simulating the intake port.

Isometric View of the Flowbench

Boundary conditions:

Inlet total pressure 172369 pa at temperature 293.2k

Outer static pressure is taken as 101325 pa at temperature 293.2k

Grid dependency test:

Grid dependency test is also called as mesh dependence test, in which the model is subjected to successive smaller cell sizes for calculations, that is the model is divided into smaller number of parts called as elements and calculations are made. As the element size decreases the error towards the result reduces.

CASE SETUP

1. The model is created using the dimensions mentioned above.
2. Then using the ‘Flow Simulation’ option lids are created at open ends. These lids help us to define the boundary condition.
3. Then using the ‘Wizard’ option in‘Flow Simulation’, features and required conditions are set
4. The Analysis type is set to Internal and Fluid is chosen as Air.All other parameters are set as default.
5. After this, the ‘Boundary Conditions’ are set using the ‘Insert Boundary Condition’ option. The boundary conditions: Inlet Total Pressure 172369 Pa at Temperature 293.2 K, and Static Pressure 101325 Pa at Temperature 293.2 K at outlet.
6. Surface Goals were set as Total Pressure on the Inlet and Outlet.
7. A Cut plot was also made on the Front Plane for observing Velocity Contours.
8. Then the Grid Dependency Test is carried out for mesh levels 3,4 and 5(on the basis of Goals.i.e.Total Pressure at outlet)
9. It was found out that mesh level 5 was the best grid.
10. New Goal i.e.Mass Flow rate(from outlet) is inserted
11. Then a new Parametric Study was done taking Input Parameter as Valve Lift(Dimension Parameter) and varying it from 1mm to 8mm using the ‘Range with Numbers’ option;and Output Parameter as the Cut Plot and Goals(Mass Flow rate).
12. These 8 different scenarios are set upand the simulation is Run.
13. Then the results were obtained.

Section View of the Flowbench

Mesh level-5

RESULTS

For Grid Dependency Test

It can be observed that the Static Pressure at Outlet is best(nearest with respect to the actual value i.e.101325 Pa) for Mesh level 5, so it is chosen.

Velocity Cut Plots for-

Valve Lift= 1 mm

Valve Lift= 2 mm

Valve Lift= 3 mm

Valve Lift= 4 mm

Valve Lift= 5 mm

Valve Lift= 6 mm

Valve Lift= 7 mm

Valve Lift= 8 mm

Results:

Variation of Mass Flow Rate with Valve Lift:

OBSERVATIONS

• As the grid gets finer, the variation in parameters is very less.
• It is observed that the Mass Flow rate increases with increase in Valve Lift
• Also the maximum velocity is not directly proportional to Valve Lift.

CONCLUSION

Therefore, the Simulation for Flow through a Flowbench is successfully completed and the results are studied.