The Internal Combustion Optical Sensor for CNG (ICOS-CNG) from LaVision provides a measurement technique for highly time resolved gas analysis directly in the combustion chamber of internal combustion methane or CNG gas engines. The gas concentration and the local air/fuel ratio are measured with crank-angle resolution. This offers the analysis of the gas mixture formation within hundreds of cycles by this system.
Crank-angle resolved Lambda-values inside a gas engine with direct port injection are measured with the ICOS-CNG system using a spark plug probe. The engine runs at constant conditions and is operated with methane. The diagram shows the evolution of the Lambda-value at the spark plug location with an early injection at different applied air-fuel-ratios. The process of mixture formation leads to a change from lean to rich mixture before stabilizing at the time of ignition.