14 days MOT/PHYM-E
- Engineers and technical staff from design department, testing department wishing to improve their knowledge on following items: engine operation, physics of engines, components design.
- This course provides a deeper knowledge on engine operating physics, under the mechanical aspects, air loading, fuel injection, ignition, exhaust gas after-treatment.
- Upon completion of the course, participants will be able to:
- calculate real flow sections in the cylinder head, in EGR circuits or any other fluid circuit,
- understand and apply the calculation formulae used during dyno bench tests,
- analyze some test results on emissions and efficiency,
- analyze the component damage and failure causes,
- understand the language and the tools used to analyze vibrations.
- No prerequisites for this course.
Ways and means
- Many exercises simulating reveryday situations in every chapter.
Week 1 3.5 days
- Engine thermodynamic operating (1.5 days)
- Thermodynamics basic knowledge: first and second principles, engine efficiency limits. Internal energy, enthalpy, entropy. Ideal gas equation. Laplace equation. Thermodynamic cycles, Beau de Rochas cycle.
- Compressor isentropic efficiency.
- Engine architecture - Performance and efficiency parameters (2 days)
- Geometric parameters: bore, stroke, volumetric ratio, timing diagram.
- Effective mean pressure: MEP, MFP, MIP.
- Real cycle, differences with theoretical cycle.
- Global efficiency: analysis using the 4 efficiencies and setting parameter influence.
- Fuel/air ratio, volumetric efficiency: calculation of the main engine parameters at stabilized rpm.
- Adaptation to the vehicle: Willans line.
Week 2 3.5 days
- Engine mechanics (1.5 days)
- Determine the movements of stresses due to gas pressure in the parts.
- Stresses caused by gas pressure and inertia stresses, impact of the conrod spacing on acyclisms.
- Acyclism consequences and solutions to limit their impact on the powertrain.
- Inertia stresses caused by the rotating weight and the alternative weight.
- Calculation of rotating and alternating inertia forces.
- Timing: description of the different valve control types, lift law, valve timing.
- Air loop (2 days)
- Link between loading and performances. Fluid mechanics.
- Air loading.
- Variable timing: presentation of the main technologies and their applications.
- Turbocharging: operating, technology, mapping, adaptation process.
Week 3 3.5 days
- Combustion (2 days)
- Air and fuel. Heating value. Ignition equation. Stoichiometric quantity. Equivalence ratio. Specific energy of an air/fuel mixture. Application exercise.
- Gasoline combustion: flame front propagation, influence of turbulence; influence of the burning rate (HLC) and of the combustion timing (CA 50) on the efficiency; exhaust gas composition depending on the equivalence ratio; calculation of specific emissions, abnormal combustions (knock, pre-ignition, rumble).
- Diesel combustion: self-inflammation delay, pre-mixture and diffusion flames, formation of pollutants (PM, NOx, HC, CO). Common-rail injection systems; swirl number, EGR.
- Fuels (1 day)
- Fuels groups: fuel main required properties for engine operating (heat value, volatility), octane and cetane ratings, Diesel fuel resistance to cold, sulfur content, …
- Manufacturing process of fuels in a refinery.
- Biofuels: fuels-ethanol mixtures, vegetable oils, fatty acid esters.
- Exhaust gas after-treatment (0.5 days)
- Structure and operating of oxidation catalysts (Diesel) and trifunctional ones (gasoline). Starting, efficiency. Ageing mechanisms. OSC (Oxygen Storage capacity). Oxygen probe. NOx traps, SCR (Selective Reduction Catalyst). Particles filtration.
Week 4 3.5 days
- Materials - Mechanical strength (1.5 days)
- Metallurgist basic tools: iron/carbon diagram, TTT, CCT. Characteristics of the alloy steels used in the automotive industry: cast irons, steels, alumina. Rough casting manufacturing processes. Surface treatment. Parts mechanical properties: Young’s modulus, minimum yield, shear rating. Analysis of the engine major parts whose material and manufacturing process have to be chosen.
- Part damage modes (1 day)
- Thermal, mechanical and tribologic damages. Goodmann diagram. Stribeck curve.
- Vibro-acoustics/NVH (1 day)
- Waves and sound: magnitudes defining a wave, propagation mode (air, solids). NVH vocabulary: dB, dBA, harmonics, resonance …
- Signal creation and lock-on, analysis and interpretation (sonogram, tracking).
- Powertrain noises and vibrations. Attenuation, isolation. Vibration impact on the surrounding parts. Line shafting vibration.