Glossary

vaporization which ensures a long enough interval for perfect combustion at all times under any conditions.

The vaporization depends upon the type of crude the fuel is derived from and therefore its volatility, viscosity and superficial tension;

fluidity at low temperatures which ensures the adduction of the fuel into the combustion chamber even at very low temperatures of below –50°;

volatility which must be low enough to prevent bubbles of steam blocking the fuel flow but high enough for easy engine start up;

viscosity which must fall between strictly controlled values to ensure that the jet nozzles work well;

calorific value which must be as high as possible both for its volume and weight. All vehicles on the road and sea need to carry the fuel they need with them but this is even more important in aviation;

thermal stability in flight the fuel is subjected to continual thermal stress with very high shifts in temperature. This should not alter its structure and all the fuel's properties should therefore remain unchanged in its performance of the range of complex functions. Today, thermal stability is the most important quality parameter that builders of engines for aircraft designed to fly at supersonic speeds are centring their interest on;

ease of combustion once the fuel finally reaches the combustion chamber it must be able to burn very rapidly, completely and should not generate smoke or any particles as these could reduce the energy efficiency of the turbine;

explosivity / inflammability above all these parameter regulates aspects of safety on the ground.

Apart from the usual ban on smoking and the compulsory fitting of flame blockers on the exhausts of vehicles circulating inside airports, once again the fuel takes care of its own safety with additives ensuring the elimination of electrostatic charges and therefore any possibility of causing an explosion or fire during refuelling.

In response to all these requirements in performance, over time jet fuel has become a highly refined product moving increasingly towards being defined as a special chemical product rather than a traditional fuel.