Improving Combustion Process by Using a High Speed UV-Sensitive Camera

The ever increasing demands on combustion engines with regard to exhaust emissions and fuel consumption require the use of modern analytical methods. Especially optical measurement techniques have contributed a lot to the realization of complicated engine concepts. The disadvantages of complex measurement techniques are the expenditure of time and the necessary changes of the engine.

This paper introduces a new practice oriented optical measurement technique with the aid of an example. With this technique it is possible to record the combustion process with a sampling rate of up to 200 kHz through a small drilling.

Even quick events like knocking can be recorded. The combustion luminosity is watched through a special UV-capable borescope, transmitted to an array of photoelectric transformers and finally recorded as a flame figure. We will show an SI-engine which is limited by knocking. Analyzing the optical images will show that the combustion process tends to burn to one side of the combustion chamber. It was possible to influence the combustion with flow corrections which resulted in a displacement of the knocking threshold and ultimately in a higher efficiency of the engine.