Exam Question

### (a) Description and Causes of Nozzle Burning (6 Marks)
**Description:**
Nozzle burning is the material degradation of a fuel injector's nozzle tip due to excessive thermal loading. The nozzle tip, which is exposed to the harsh conditions of the combustion chamber, overheats beyond its material design limits. This leads to the metal softening, eroding, cracking, and literally 'burning away'. The failure is often characterized by discoloration (a bluish tint), formation of craters, and deformation of the spray holes, which severely compromises fuel atomisation and engine performance.
**Causes of Nozzle Burning:**