Modelling and simulation of flow through a flowbench
Modelling and simulation of flow through a flowbench
Objective:
To Create a 3D Model of owbench simulate ow analysis (CFD Analysis) and obtain a plot of Lift vs Mass Flow rate.
Theory:
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 ows. Computers are used to perform the calculations required to simulate the free-stream ow of the fluid, and the interaction of the fluid (liquids and gases) with surfaces defined by boundary conditions.
Air Flow Bench:
An air ow 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 ow capabilities of any component such as air lters, carburetors, manifolds or any other part that is required to ow 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.
Grid Dependency Test:
It is analysis of Model (FEA/CFD) in which the input conditions remains same whereas the Meas re nement changes over every run. Meshing can be started from Coarse Mesh to Finer Mesh. Simulation with more and more ner mesh will help to achieve an actual solution. The grid dependency test is an feasible tool to obtain the ideal grid re nement required for the Simulation.
Geometry:
- Analysis type :- Internal
- Working Fluid :- Air
- Boundary Conditions
- Velocity @ Inlet Valve = 100m/s
- Static Pressure @ Cylinder Outlet FaceAdd Goals
- Global Mass Flow Rate
- Surface Mass Flow Rate @ Cylinder Outlet Face
- Valve Lift = 1mm
- Global Mesh Level = 3 with Advance Channel Refinement
Results:
Velocity Flow
Pressure Flow
Flow trajectory
Grid Dependancy Test:
With the same above Baseline Setup, Create new Parametric Study
Input Variables
Global Mesh -> Automatic Mesh -> Level of Initial Mesh
Output Variables
Goals -> SG Mass Flow Rate
Results -> Cut Plots
Scenarios
Add 3 Design Points with Level of Initial Mesh=3, 4, 5, 6
RUN the Parametric Study & Evaluate Results
Results:
Velocity Plots
Design Point 1 :- Level 3 refinement
Design Point 2 :- Level 4 refinement
Design Point 3 :- Level 5 refinement
Design Point 4 :- Level 6 refinement
Pressure plots
Design Point 1 :- Level 3 refinement
Design Point 2 :- Level 4 refinement
Design Point 3 :- Level 5 refinement
Design Point 4 :- Level 6 refinement
Comparision on grid size:
NOTE:
Surface Mass Flow Rate Values are Negative because of the fact that Fluid is Leaving out of the Domain in Flow Simulation. Only Magnitude can be considered for further study.
Higher the Level of Re nement, better will be the Simulation. Hence will choose 6th Level of Mesh Re nement for Valve Lift Study.
Valve Lift Parametric Study:
Create another new Parametric Study,
Input Variable
Level of Initial Mesh -> Set discrete value to 6
Add Dimension -> Select Lift Dimension
range with numbers :- (0.001-0.007),7 values
Output Variable
Add Goals -> SG Mass Flow Rate
Add Results -> Cut Plots & Flow Trajectory
8 Scenarios will be created
RUN the Simulation:
Results:
Design Point 1 :- Valve Lift = 1mm
Velocity Plot -- velocity Trajectory-pressure plot
Design Point 2 :- Valve Lift = 2mm
Velocity Plot -- velocity Trajectory-pressure plot
Design Point 3 :- Valve Lift = 3mm
Velocity Plot -- velocity Trajectory-pressure plot
Design Point 4 :- Valve Lift = 4mm
Velocity Plot -- velocity Trajectory-pressure plot
Design Point 5 :- Valve Lift = 5mm
Velocity Plot -- velocity Trajectory-pressure plot
Design Point 6 :- Valve Lift = 6mm
Velocity Plot -- velocity Trajectory-pressure plot
Design Point 7 :- Valve Lift = 7mm
Velocity Plot -- velocity Trajectory-pressure plot
comparision of mass flow rate at outlet with respect to the valve lift:
| Goal (Value) | Design Point 1 | Design Point 2 | Design Point 3 | Design Point 4 | Design Point 5 | Design Point 6 | Design Point 7 |
| valve lift [m] | 0.001 | 0.002 | 0.003 | 0.004 | 0.005 | 0.006 | 0.007 |
| SG Mass Flow Rate 1 [kg/s] | -2.11601E-46 | -1.99495E-46 | -1.392120373 | -0.566522925 | -0.033113924 | -0.028220765 | -0.026808914 |
Graph plot
Conclusion:
- At Lower Valve Lift, Higher Velocity is build up near the Valve Inlet and decreases with Increase with the lift.
- Pressure at the Valve Opening also decreases with Increase in the lift.
- An optimal lift has to be designed for the proper ow of Air with Optimal Velocity and Optimal Pressure.
- Valve lift of 2mm & 3mm seems to be Optimal Lift openings where a required Swirl is developed above the Valve Surface which is then sprayed on the walls of the Cylinder Completely.
- The Mass Flow rate at the Inlet of the Valve and Outlet at the Lid also Increases with increase in the Lift.