Modelling and simulation of flow through a flowbench

AIM:

To create a 3D model and then do a flow simulation of a Flow bench using SOLIDWORKS

THEORY:

Air flow bench is a device used for testing the internal aerodynamics 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.

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 defined by boundary conditions.

BASELINE INPUTS:

Type of flow : Internal

Working fluid : Air

Total inlet pressure : 6 MPa

Static outlet pressure : 0.1 MPa

Global and Local Mesh level : 4

PROCEDURE:

• Create a 3D model with port (here helical inlet port) and a valve and then convert it into a shell of 2 mm thickness. Here bore diameter is 250 mm.

• Now start with the flow simulation. Create lids at the inlet of port and at outlet of the cylinder. Provide boundary conditions like total pressure at the inlet port and a static pressure at the outlet of the cylinder.

• Now set goals, here it is a surface goal of mass flow rate.
• Now set the mesh level and also set the local mesh level for better refinement near the surfaces of the valve for better results.

• Now run a parametric study in which the input variable is the distance between the valve and the cylinder (valve lift), select the dimension and then select the range and provide the number of points in between them. (i.e. 3mm, 4mm, 5mm, 6mm, 7mm)

• Now for output parameters, select all the plots used in the simulation of 3 mm valve lift and then run the simulation.

RESULTS:

FOR 3 MM VALVE LIFT

FOR 4 MM VALVE LIFT

FOR 5 MM VALVE LIFT

FOR 6 MM VALVE LIFT

FOR 7 MM VALVE LIFT

PLOT FOR MASS FLOW RATE AT DIFFERENT VALVE LIFT

CONSLUSION:

From the above study we can say that parameters such as pressure, velocity and mass flow rate are critical for designing of flow bench. We can see that as the valve lift increases, the velocity at the inlet port also increases but the pressure decreases. There is also a variation in the mass flow rate at different valve lifts, as the valve lift increases the mass flow rate also increases. It can also be seen that with the increase in the valve lift the trajectory line area also decreases, at lower valve lifts the trajectory lines covers more area in the cylinder.