Ricardo Wave Simulation for single cylinder SI engine

Key points:

Our goal was to evaluate the performance of a single cylinder SI (spark-ignition) engine based on the following parameters:

1) Injection Timing,
2) Compression Ratio,
3) Engine load and
4) Volumetric Efficiency

Screenshot from Ricardo Wave for a single cylinder SI engine model

Step 1 - The following parameters were set from Wave Solver:

1) Compression Ratio - 18:1
2) Engine nominal speed - 2000 rpm
3) Fuel flow rate - 1 kg/hr
4) Intake pressure - 1.3 bar abs.
5) Injection Duration - 7 degree CA (Crank Angle)
6) BMEP (Brake Mean Effective Pressure) - 0 bar
7) Lambda (Excess air ratio) - 8.65

Screenshot from Ricardo Wave indicating the input parameters

Step 2 - Using the sweep function, injection timing was swept over engine speed range.

Here's a link to the final report which includes all the outputs. 

(https://drive.google.com/open?id=1eePjubGn2xNWMnLGcIHHGCp0DekaBFpS)

Learning outcomes from this project:

1) As the engine speed in increased, the max Indicated mean effective pressure is achieved only by retarding the injection timing.

2) Combustion phasing is the time in the engine cycle, specifically the compression and expansion strokes, where combustion occurs and it characterizes how energy and work potential of the energy from the fuel are utilized. We can see from the plots that at a given engine RPM, as combustion phasing increases, the maximum pressure in the cylinder is decreasing; BSFC remains constant until 3500rpm beyond which it increases significantly.

3) As the compression ratio was increased, the ignition delay needed to be retarded to ensure complete combustion of the mixture, this is because as clearance volume is reduced, pressure & temperature at the end of the stroke are higher which leads to better penetration of fuel & higher chances of its' finding oxygen, thereby forming a stoichiometric mixture which is favorable for combustion.