Internal Combustion Engines Course Quiz

Study Notes

Course material covers internal combustion engines.
Topics include engine geometric parameters, theoretical and real Otto cycles, and engine efficiencies.
Engine geometric parameters include bore, stroke, connecting rod, and crank radius.
Swept volume is the volume displaced by the piston.
Clearance volume is the volume remaining in the cylinder at the top dead center (TDC).
Compression ratio is the ratio of the swept volume to the clearance volume.
Mean effective pressure (MEP) is the average pressure exerted on the piston during a cycle.
Indicated work (Wi) is the work done within the engine cylinder.
Brake power (Wb) is the power available at the engine crankshaft.
Friction and pumping power (Wf) is the power lost due to friction and pumping.
Specific fuel consumption (SFC) is the amount of fuel used per unit of power output.
Mechanical efficiency (ηm) is the ratio of brake power to indicated power.
Thermal efficiency (η) is the ratio of net work output to heat input.
Volumetric efficiency is a comparison of actual volume of air-fuel mixture drawn into the engine to the theoretical maximum volume that could be drawn in.

Combustion involves rapid oxidation of a material, usually by mixing the material (fuel) with a surrounding substance (oxidant).
Premixed flames are when fuel and oxidant are homogeneously mixed before reaction occurs, for example a Bunsen burner.
Non-premixed flames are when fuel and oxidant come into contact during combustion process, such as a candle flame.

The ratio of the mass of air to the mass of fuel in a mixture.
The AFR for specific mixture type (lean, rich, stoichiometric etc.) influences the effectiveness of the combustion process, for example an AFR may result in a more efficient combustion with less emissions.

Definitions of relevant terms about a specific engine's geometric parameters
Calculations related to geometric parameters (e.g. crank radius, stroke, etc.) are explored.

The Otto cycle is a thermodynamic cycle that governs the idealized operation of gasoline engines.
Cycle analysis is conducted under idealized adiabatic conditions, which are close to the real cycle, but not perfect.
Diagrams and mathematical expressions describe the relationship between pressure and volume in both theoretical and real cycles.

Various types of engine efficiency are covered in terms of their importance in combustion engineering
Different mechanical efficiency measures and their specific application in combustion engineering

Thermodynamics concepts are applied.
Combustion chemistry is shown to be relevant.
Numerical data and calculations related to combustion are discussed
Fundamentals of combustion, particularly the different types of flames, are discussed, focusing on premixed and non-premixed flames.
Combustion involves various chemical kinetics and other key concepts from fluid dynamics and thermodynamics.

Turbulent burning velocities and their difference from their laminar counterparts are discussed.
These differ according to the properties that describe the flow.
Typical turbulent flame structures are analyzed.

This theory analyses the two-zone combustion model, including the preheat and reaction zones in a laminar flame.
Theoretical concepts and data are integrated, with a focus on flame speed and thickness.

The principles and applications of diesel engines are discussed.
Differences between SI engines and diesel engines (e.g. in terms of combustion) are compared.

The effects and consequences of varying the spark timing during combustion are discussed.
Timing is optimized, considering the characteristics of turbulence (e.g. flame and flow).

The energy needed to ignite the fuel-air mixture required for combustion is explored
Flammability limits are explained in terms of fuel-rich or fuel-lean conditions.