Case Study on SI Engine

AIM

The aim of this simulation is to run the engine case for maximum power and torque condition

OBJECTIVES

The main objectives of this simulation are

1. Comparison of important engine parameters
2. Post processing of simulation results

SI ENGINE SIMULATION

Thus for the case Study of an SI engine the following parameters are being considered

1. 4 cylinder SI GDI Engine
2. 4 cylinders, 16 valves SOHC 73x89.4 mm
3. Naturally Aspirated Engine, Water Cooled
4. Max Power = 87.7 KW @ 6600 rpm
5. Max Torque = 145 N-m @ 4600 rpm

Engine Model

This is the engine model of 4 cylinder SI GDI Engine with a catalytic converter

In the above image we see the results for before modifications where the 103 KW of brake power is being produced at 6600 rpm and the brake torque of 192.9 N-m of brake torque is being generated at 4600 rpm.

Engine Geometry Modifications

Certain modifications were made on the engine geometry like bore is set to 73.4 mm and the stroke is changed to 89.4 mm

Inlet Valve Cam Timing Modification

In accordance with the engine specifications which are already set, we have to change the Inlet valve cam timing angle from 225 deg to 222 deg. In order to comply with the power and torque set we decrease the cam timing angle. The inlet valve will now start to open from 222 deg rotation of the camshaft.

Fuel Injector Modification

Now the fuel Injection delivery rate was also changed to 7 g/s for the compliance with power output.

Injection Timing

The injection timing angle was also varied from 368 deg to 370 deg. The injection timing angle is increased to the optimum power and torque output.

Exhaust Valve Cam timing

The exhaust valve was also changed from 125 deg to 122 deg for the required power output

Results

Brake Power and Torque

Here the power is 87.4 KW and the brake torque is at 144.8 N-m

PV Diagram

Log PV Diagram

Cylinder Pressure

Burn rate

Inlet Mass flow rate

Exhaust Valve Mass flow rate

Pumping Loop

CONCLUSION

1. Critical Engine parameters are changed to get the required power and torque from the engine
2. Engine geometry were changed from the engine specified at the start of the simulation
3. Various plots can be generated and observed for the engine performance