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# Engine Operating Physics

14 days
MOT/PHYM-E
Sessions
This course is not scheduled.
Who should attend?

Audience

• Engineers and technical staff from design department, testing department wishing to improve their knowledge on following items: engine operation, physics of engines, components design.

Level

• Foundation
• This course provides a deeper knowledge on engine operating physics, under the mechanical aspects, air loading, fuel injection, ignition, exhaust gas after-treatment.
Learning Objectives
• 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.
Course Content

## Week 1

3.5 days

• Engine thermodynamic operating (1.5 days)
• History.
• 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)
• Acyclism
• 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.
• Balancing
• 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)
• 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.
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