Fuel Film Diagnostic Development Of A Spark Ignited Homogeneous Charged Four Stroke Air Cooled Engine

The main objective of this research has been to develop techniques for qualifying and quantifying fuel film development in the intake port of a small air-cooled four-stroke utility engine. These techniques should be able to quantify the total mass of fuel film in the intake port under various operating conditions. Such techniques would determine operating conditions that lead to the formation of fuel films, yielding information into fuel film behavior and possible means of reducing such effects. To achieve the above-mentioned objectives, five methods were used to assess fuel films under various operating conditions. The five methods used to assess fuel films were 1. Indolene- and propane-fueled impulsive fueling transients using a heated universal exhaust gas oxygen (UEGO) sensor as a diagnostic. 2. Indolene- and propane-fueled impulsive throttle transients using a UEGO sensor as a diagnostic. 3. Capacitance fuel film measurements. 4. Skip-injection with fast flame ionization detector (FFID) exhaust hydrocarbon sampling. 5. Stop-injection with FFID exhaust hydrocarbon sampling. The thesis is presented as follows. Chapter 2 consists of a literature review of various other research work conducted on fuel film behavior. In Chapter 3, the laboratory setup and equipment used for this experiment is presented such that the experiment could be independently repeated. Chapter 4 consists of characterizing the response time of the UEGO sensor that is used for both the impulsive fuel and impulsive throttle transient tests listed as 1 and 2 above. Statistical tests are also presented that verify the validity of the tests. In Chapter 5, the techniques and results of the indolene- fueled impulsive transients are presented. In Chapter 6, the techniques and results to indolene and propane impulsive throttle transients are presented. In Chapter 7, a localized capacitance technique of measuring film thickness is presented. Two methods of calibrating the sensors are presented, as well.