Modelling and simulation of flow through a flowbench using Solidworks
Aim- To create a 3D model of a flow bench and simulation of flow through the flowbench and do the following-
Grid dependence test
For three grids run the simulation at a particular valve lift and explain the results
Effect of valve lift on mass flow rate
Once the best grid is decided, run a parametric sweep to show the effect of valve lift on mass flow rate
Theory-
INTRODUCTION: An airflow 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 primarily used for testing the intake and exhaust ports of cylinder heads in an internal combustion engine. it is also used to test the flow capabilities of air filter, carburetors, manifolds or any other part that is required to flow air or gas. 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.
In this project, we are going to model the flow bench and simulate the airflow from the inlet port to the outlet using Solidworks.
Input Parameters
- External diameter of cylinder : 0.10m
- Height of cylinder : 0.10m
- External diameter of Inlet Manifold : 0.025m
- Shell : 0.002m
- Inlet Total Pressure : 172300 Pa
- Outlet Static Pressure : 101325 Pa
PROCEDURE
1) Create a cylinder with diameter 0.10m and extrude it to 0.10m. Then make the circular inlet port by sweeping circular profile of diameter 0.025m and shell the cyliner with thickness 0.002m.
2) Create axis at the bottom of the intake port then create plane over there and by using that plane create the valve.
3) Make the valve open at 0.004m and then create lids at the inlet and outlet.
4) Save the profile and run the wizard by setting all the conditions and add working fluid as air.
5) Insert boundary conditions as Total inlet pressure as 172300 Pa and Static pressure at the outlet as 101325 Pa.
6) Constraint the valve in such a way so that the valve can only move to the vertical distance.
7) Run the basic simulation then run parametric study by taking Local Global mesh as input to do the grid dependency test.
8) Set global and surface goals of the mass flow rate through the flow bench.
9) Create Local Global mesh around the valve.
10) Create cutplots of the velocity and the pressure, and surface goal plot of the mass flow rate through the flow bench and also create flow trajectory around valve.
11) Now run parametric study by taking Local Global mesh as input and make it to range from 3 to 5 grid with 3 values between them & also specify the input parameters of total pressure inlet, static pressure outlet, and the initial temperature and run the study & at that point valve lift is 0.004m.
12) Now decide the best grid.
13) Now generate a new parametric study, and specify the dimension parameter as the valve lift dimensions, and vary the dimensions as 2mm, 4mm, 6mm, 8mm, 10mm & specify the Local Global mesh with the best grid is decided (in this case it is refined grid 5).
14) Also, specify the input parameters of inlet total pressure, outlet static pressure, and the initial temperature.
15) Now select the required output such as cut plots, flow trajectory, goal plot, and the mass flow rate at the surface goal. Finally, run the parametric study and get the required results and output plots.
16) Save and conclude the results.
Results
- Table obtained during Grid dependency test with valve lift 0.004m
| Goal | Design Point 1 | Design Point 2 | Design Point 3 |
| Level of initial mesh (Automatic Mesh) [ ] | 3 | 4 | 5 |
| D5@[email protected] [m] | 0.004 | 0.004 | 0.004 |
| Static pressure (Static Pressure 1) [Pa] | 101325 | 101325 | 101325 |
| Temperature (Static Pressure 1) [K] | 293.2 | 293.2 | 293.2 |
| Total Pressure (Total Pressure 1) [Pa] | 172300 | 172300 | 172300 |
| GG Mass Flow Rate 1 [kg/s] | 1.10795E-05 | 2.64046E-06 | 2.25687E-06 |
| SG Mass Flow Rate 1 [kg/s] | -0.033754966 | -0.03491597 | -0.03250348 |
Case 1: Local Mesh Frid is 3
- Pressure Contour
- Velocity Contour
Case 2: Local Mesh Frid is 4
- Pressure Contour
- Velocity Contour
Case 3: Local Mesh Frid is 5
- Pressure Contour
- Velocity Contour
From the above study on the grid dependency test, it is observed that the mesh refinement value or grid value of 5 gives varied results for the velocity plot and gives an accurate value of the mass flow rate. So, from here on we are going to select the grid size 5 as the best grid and continue with our experimentation.
- Parametric Study at best grid (5)
| Goal | Design Point 1 | Design Point 2 | Design Point 3 | Design Point 4 | Design Point 5 |
| D5@[email protected] [m] | 0.002 | 0.004 | 0.006 | 0.008 | 0.01 |
| Level of initial mesh (Automatic Mesh) [ ] | 5 | 5 | 5 | 5 | 5 |
| Static pressure (Static Pressure 1) [Pa] | 101325 | 101325 | 101325 | 101325 | 101325 |
| Temperature (Static Pressure 1) [K] | 293.2 | 293.2 | 293.2 | 293.2 | 293.2 |
| Total Pressure (Total Pressure 1) [Pa] | 172300 | 172300 | 172300 | 172300 | 172300 |
| GG Mass Flow Rate 1 [kg/s] | -1.66E-08 | 2.18E-05 | 1.36E-05 | 1.48E-05 | 3.28E-05 |
| SG Mass Flow Rate 1 [kg/s] | -6.67E-46 | -0.0325 | -0.0579 | -0.0648 | -0.0671 |
Case1 : For a valve-lift of 2mm (0.002m)
- Pressure Contour
- Velocity Contour
- Flow Trajectory
Case2 : For a valve-lift of 4mm (0.004m)
- Pressure Contour
- Velocity Contour
- Flow Trajectory
Cas3 : For a valve-lift of 6mm (0.006m)
- Pressure Contour
- Velocity Contour
- Flow Trajectory
Case4 : For a valve-lift of 8mm (0.008m)
- Pressure Contour
- Velocity Contour
- Flow Trajectory
Case5 : For a valve-lift of 10mm (0.010m)
- Pressure Contour
- Velocity Contour
- Flow Trajectory
- Variation in mass flow rate through the flow bench at different valve lift or design point
- Variation in mass flow rate through the outlet port at different valve lift or design point
- Variation in mass flow rate through the flow bench vs iterations at different design points
- Variation in mass flow rate through the outlet port vs iterations at different design points
Conclusion (Effect of Valve Lift)
1) From the velocity plots, we saw as the valve lift increases the velocity of fluid also increases. Hence higher the valve lift higher will be the velocity of fluid.
2) From the pressure plot, we saw as the valve lift increases the pressure of the fluid decreases. Hence higher the valve lift lower will be the pressure of fluid.
3)From the above study of valve lift analysis, it is observed that the value of the mass flow rate of air (fluid) leaving the surface increases as the valve-lift at the cylinder inlet increases. The negative(-ve) sign of the mass flow rate indicates that the fluid (air) is leaving the domain.
4) When the lift is small the pressure developing is very small & it increases as the valve lift increases.
5) Initially pressure drop is high so gas is having tendency to move from high pressure to low pressure hence. we can say mass flow rate through outlet port is more when valve lift is less & decreases as the valve lift increases.
6) Higher the level of grid in the mesh more accurate will be the results.