Experimental investigation of the air–fuel charging process in a four-valve supercharged two-stroke cycle GDI engine

  • Macklini Dalla NoraEmail author
  • Thompson Diórdinis Metzka Lanzanova
  • Mario Eduardo Santos Martins
  • Paulo Romeu Moreira Machado
  • Hua Zhao
Technical Paper


Fuel consumption standards imposed in several countries for the next years have prompted the development of hybrid passenger cars with ever smaller internal combustion engines. In such powertrain, fuel consumption is as important as engine packaging and power density, so two-stroke engines may be an option due to their higher combustion frequency compared to four-stroke engines. Therefore, the present research investigates the air–fuel charging process of an overhead four-valve direct injection supercharged engine operating in the two-stroke cycle. The optimum start of fuel injection was evaluated for commercial gasoline by means of indicated and combustion efficiencies where a trade-off was found between early and late fuel injections. By advancing the injection timing, more fuel was prone to short circuit to the exhaust during the valve overlap, while late injections resulted in poor charge preparation. The gas exchange parameters, i.e. charging and trapping efficiencies, were obtained from seventy operating points running at fuel-rich conditions. The Benson–Brandham mixing-displacement scavenging model was then fit to the experimental data with a coefficient of determination better than 0.95. With such model, the air trapping and charging efficiencies could be estimated solely based on the scavenge ratio and exhaust lambda, regardless of the engine load, speed, or air/fuel ratio employed. Further twenty-five different lean-burn testing points were tested to certify the proposed methodology applied to the poppet valve two-stroke engine. The in-cylinder lambda was calculated and found different from the exhaust lambda due to mixing between burned gases and intake air during the scavenging process.


Two-stroke cycle engine Overhead poppet valves Fuel injection timing Gasoline direct injection Benson–Brandham scavenging model Lean-burn combustion 



After top dead centre


Crank angle


Charging efficiency


Direct injection


Exhaust gas recycling


Exhaust valve closing


Exhaust valve opening


Gasoline direct injection


Indicated mean effective pressure


Intake valve closing


Intake valve opening


Water–gas equilibrium constant

LHVfuel, LHV

Lower heating value of fuel

\({\text{LHV}}_{{{\text{H}}_{ 2} }}\)

Lower heating value of hydrogen


Lower heating value of solid carbon


Lower heating value of carbon monoxide


Lower heating value of unburned hydrocarbons


Intake air mass per cycle

\(m_{{{\text{trap }}\;{\text{air}}}}\)

In-cylinder trapped air mass per cycle


Air mass flow rate


Fuel mass flow rate


Mass flow rate of soot


Mass flow rate of carbon monoxide

\(\dot{m}_{{{\text{H}}_{2} }}\)

Mass flow rate of hydrogen


Mass flow rate of unburned hydrocarbons


Oxides of nitrogen


Port fuel injection


Revolutions per minute


Coefficient of determination


Air short-circuiting


Spark ignition


Start of fuel injection


Scavenge ratio


Scavenge ratio of perfect displacement


Air trapping efficiency


Fuel trapping efficiency


Three-way catalyst


Unburned hydrocarbons


Clearance volume


In-cylinder volume at intake valve closure


Hydrogen-to-carbon ratio


Volumetric exhaust carbon monoxide concentration


Volumetric exhaust nitrogen oxides concentration


Soot concentration


Volumetric exhaust unburned hydrocarbons concentration


Combustion efficiency


Relative air/fuel ratio (lambda)


In-cylinder lambda


Exhaust lambda


Intake air density



The first and second authors would like to acknowledge the Brazilian council for scientific and technological development (CNPq–Brasil) for supporting their PhD studies at Brunel University London.


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Copyright information

© The Brazilian Society of Mechanical Sciences and Engineering 2019

Authors and Affiliations

  1. 1.Engines Research Group (GPMOT)Federal University of Santa MariaSanta MariaBrazil
  2. 2.Centre for Advanced Powertrain and Fuels Research (CAPF)Brunel University LondonUxbridgeUK

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