MODELLING AND SIMULATION OF FLOW THROUGH A FLOWBENCH
1.AIM :
TO MODEL AND SIMULATE FLOW THROUGH A FLOWBENCH VALVE GEOMETRY FOR VARYING VALVE LIFTS
2.OBJECTIVE :
- To create a 3D model of a flow bench and run flow analysis using Soildworks flow simulation.
- To conduct grid dependency test on model to decide the best grid.
- To run a parametric study to show the effect of valve lift on mass flow rate for the best grid.
- To determine effect of valve lift on mass flow rate.
3.INTRODUCTION :
Flow simulation through a flowbench can be performed through computational fluid dynamics (CFD), a powerful and convenient tool to perform CFD is Solidworks flow simulation.
Computational fluid dynamics (CFD) is a branch of fluid mechanics that uses numerical analysis and data structures to analyze and solve problems that involve fluid flows. Computers are used to perform the
calculations required to simulate the free stream flow of the fluid, and the interaction of the fluid with surfaces dened by boundary conditions.
In simple words to perform CFD following steps are performed in order:-
A computational model is made using computer aided designing and the domain of fluid is extracted.
Further the domain is divided into discrete cells called mesh.
Next the Boundary conditions are defined, which is specifying the fluid behaviour and properties at all bounding surfaces of the fluid domain.
Next the calculations are performed and the equations are solved iteratively till the convergence is achieved.
Finally the analysis and visualization of the calculations performed can be seen.
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.
Here in this work an air flow bench is modeled and flow analysis is performed on it. Initially a grid dependency test is performed for grid size 3,4,and 5 at 1mm valve lift and then after deciding the best grid size a parametric study on the best grid is performed to show the effect of valve lift on mass flow rate.
4.PROCEDURE :
1)At first the flow bench is modeled using Solidworks.
Cut section of model flowbench model
2)Lids are added to inlet and outlet port.
3)Using the wizard option in Soildworks flow simulation a new project is created. The analysis type selected is Internal.
4)Air is selected as the working fluid.
5)At inlet a total pressure of 101325 Pa boundary condition is inserted.
6)At outlet a static pressure of 51325 Pa boundary condition is inserted.
7)Global mesh is created, initally of mesh size 3.
8)A surface goal of mass flow rate on outlet lid, a velocity cut plot in the centre front view, a surface parameter for mass flow rate at outlet, a flow trajectory from input face to output face is inserted.
9)The same process is done for mesh size 4 and 5 to determine the best mesh grid, and after detemining the best mesh grid a parametric study is performed with the valve lift dimension as the input variable varying from 1 to 5mm with a total of 5 values.
5.RESULTS :
There are 2 studies performed, the study 1 is Grid dependency test and study 2 is parametric study taking the best grid size determined.
Results for both the study are given below
1)STUDY 1: GRID DEPENDENCY TEST
The flow simulation is performed at 3,4 and 5 mesh grid size at 1mm valve lift
Mesh grid size 3
Cut plot for velocity contour
Mesh grid size 4
Cut plot for velocity contour
Mesh grid size 5
Cut plot for velocity contour
Comparing Mass flow rate for the 3 mesh grid sizes
| MESH GRID SIZE | 3 | 4 | 5 |
| MASS GLOW RATE (Kg/s) | 0.0186 | 0.0195 | 0.0203 |
As it can be seen from the plot the mesh grid size of 5 gives a more accurate and clear plot also the value of mass flow rate is changing with with every mesh grid size indicating the the mesh grid size of 5 gives most accurate results of all 3.
Hence the further parametric study is performed deciding the mesh grid size of 5 as the best mesh grid.
2)STUDY 2: PARAMETRIC STUDY
Using the grid size of 5, a parametic study is conducted with 5 valve lift values varying from 1 to 5 mm.
valve lift : 1mm
Cut plot for velocity contour
Flow trajectories
valve lift : 2mm
Cut plot for velocity contour
Flow trajectories
valve lift : 3mm
Cut plot for velocity contour
Flow trajectories
valve lift : 4mm
Cut plot for velocity contour
Flow trajectories
valve lift : 5mm
Cut plot for velocity contour
Flow trajectories
Effect of valve lift on mass flow rate
| VALVE LIFT (mm) | 1 | 2 | 3 | 4 | 5 |
| MASS FLOW RATE (Kg/s) | 0.0008 | 0.0020 | 0.0135 | 0.0163 | 0.0179 |
Explanation
As it can be seen from the velocity contours with the increase in valve lift the velocity of air increases. The valve portion provides a restriction which makes it to ailimar to nozzle, as the air reaches and leaves the restriction there is an evident increase in velocity.
As it can be seen from the graph the valve lift increases the mass flow rate also increases but after a point the slope of the graph starts decreasing which indicates that after a point the the effect of valve lift on mass flow rate decreases.
6.CONCLUSIONS :
The simulation for flow through a flowbench was completed successfully using Solidworks flow simulation.
It can be concluded that with the increase in valve lift the velocity of air and mass flow rate increases.
7.REFERENCES :