New Combustion Developments in Diesel EnginesMOT/COMBD-E

Who should attend?

  • 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.
Audience :
  • Engineers and technical staff who have to optimize Diesel engine combustion.

Level : Advanced

Course Content

  • Fuel jet inflammation

      • 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

      • 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

      • 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

      • 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)

      • 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).

Learning Objectives

  • 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).

Ways & Means

  • One of our best-sellers.
  • Practical aspects come with dimensioning and matching simulation exercises.