Modelling and simulation of flow through a flowbench

Aim: CFD analysis of flow through a flowbench

objective:

• To perform CFD analysis of flow through a flowbench
• perform grid dependency test
• perform parametric study by changing valve lift
• do analysis of result

Therotical background:

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.

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.

Geometry:

Input data:

• Fluid:Air
• Flow: Internal flow

Boundary conditions:

• Inlet total pressure: 101325 [pa] at temprature 293.2k
• outlet static pressure: 200000[pa] at temprature 293.2 k

Procedure:

• create 3D model of workbench
• create new simulation by giving proper input
• define boundary condition
• create surface goal like average pressure at outlet
• perform parametric study based on grid dependency
• perform parametric study based on valve lift

Grid dependency test :

• Refinement level is 3

• Refinement level is 5

• Refinement level is 7

Valve lift parametric study :

• valve lift = 1mm

• valve lift = 2mm

• valve lift = 3mm

• valve lift = 4mm

• valve lift = 5mm

• valve lift = 6mm

• valve lift = 7mm

• valve lift = 8mm

Goal Value:

Goal (Value)	Design Point 1	Design Point 2	Design Point 3	Design Point 4	Design Point 5	Design Point 6	Design Point 7	Design Point 8
D7@[email protected] [m]	0.001	0.002	0.003	0.004	0.005	0.006	0.007	0.008
GG Mass Flow Rate 1 [kg/s]	-2.57032E-06	-1.16038E-05	-4.48825E-05	-5.13698E-05	-0.000107138	-5.76741E-05	0.000138606	-0.000216193
SG Mass Flow Rate 1 [kg/s]	-0.016761373	-0.02833211	-0.038758946	-0.047808486	-0.055818935	-0.062754947	-0.067388278	-0.070789625

Conclusion:

• from grid dependency test refinement level 5 gives best and less fluctuating result and refinement level 5 is used for valve lift parametric study.
• mass flow rate of air passing through flowbench increases with increase in valve lift and negative sign shows that air leaving the flowbench.
• as velocity increases with valve lift pressure decreases as air flows from high pressure to low pressure.

Result:

• CFD analysis of flow through flowbench has been successfully completed.