3 days MOT/COMBD-E
- Engineers and technical staff who have to optimize Diesel engine combustion.
- To understand, in Diesel engines:
- the role of the injection system and of aerodynamics in the cylinder on the air-fuel mixture
- the mechanisms of the mixture inflammation, of combustion and of pollutants formation
- the influence of the engine tuning parameters on performances, efficiency and emissions
- the turbocharger behavior.
- To be able to organize a series of tests and to analyze the results in order to optimize:
- the combustion system (injection system, internal aerodynamics, combustion chamber geometry)
- the engine tuning parameters (advance, injection pressure, multi-injections, exhaust gas recirculation).
- IC engines fundamentals.
Ways and means
- One of our best-sellers.
- Practical aspects come with dimensioning and matching simulation exercises.
Fuel jet inflammation 0.5 day
- Diesel engine history.
- Diesel combustion stages. Self-inflammation delay, basic knowledge on cold flames, influence of the different temperature, pressure, air-fuel ratio, residual gas parameters. Pre-mixture flame and diffusion flame combustions. Soot formation and oxidation mechanisms, nitrogen oxides and carbon monoxide formations.
- Jet structure during combustion.
Diesel combustion 1.5 days
- Optimization situation of diesel combustion system during the design process.
- Pollutants formation in heterogeneous combustion: particles, nitrogen oxides, unburnt hydrocarbons, carbon monoxide.
- The three phases of combustion. Noise. Pre-injection and post-injection.
- Injectors jets behavior: introduction rate, jets penetration and atomization, cavitation, injection jets overlap; optimization of the injector jets set, bowl shape and dimensions, swirl.
- Exhaust gas recirculation (EGR): effect on combustion, EGR cooling, interest of low pressure EGR.
- Full load performances: limiting parameters, cylinder head thermodynamic resistance; supercharging, interest of a variable geometry turbocharger.
- Start and cold start. Glow plug and post-glow plugs.
- Combustion optimization at dyno bench: injector jets positions, influence of injection advance and of low-load and high-load EGR, injection pressure, supercharging pressure. Combustion system evolutions.
- Practical exercises on dyno bench test results interpretation.
Aerodynamics - Swirl generation and measurement 0.25 day
- Interference between the swirl and the squish.
- Influence on the air-fuel mixture and on combustion.
- Defining the swirl number and the cylinder head permeability. Bowl shape in the piston.
Injection systems 0.25 day
- Injectors nozzles, injector holes flow rate coefficient, hydraulic flow rate.
- Exercise: determining a hydraulic flow rate.
- Common-rail injection systems technologies: solenoid control (balanced or unbalanced electrovalve), piezo-electric control, 2-way and 3-way valves, direct piezo control, pressure amplification systems.
Homogeneous charge compression ignition (HCCI) 0.5 day
- Operating principle, interest, examples of developments.
- Critical points: operating area without NOx formation, HC and CO emissions, high load operating, combustion control.
- Technologies to be implemented to optimize the concept as a whole: combustion system, exhaust gas after-treatment, engine control (acting on the exhaust gas recirculation, the turbocharger, the inlet temperature, the variable timing).