Paper 5: Some Experiments on the Mode of Action of a Diesel Smoke Suppressant Additive

The use of a smoke suppressant additive is very effective in reducing smoke but has only a marginal effect upon all aspects of engine performance. Photographed flame in the engine appeared to burn out earlier with the additive and at a time when gas temperatures were high. Thus, the additive was not just a catalyst for low-temperature burning of carbon. Quantitative measurements of carbon formation could not be achieved, so it is not possible to state with certainty whether the additive reduces carbon formation. The photographs do not show an observable difference of carbon formation. The most likely mechanism of action of the additive is by assisting the burning of carbon at the early stages of the engine expansion stroke.