I don't know of any thrower, javelin or otherwise, who smells their implement. It could be that you are misinterpreting the position of the javelin close to the head during runup. read more
Most throwers yell or grunt when throwing any implement, not just the javelin. They believe that exhaling air rapidly gives them extra energy rather than holding the air inside. This principle is also used in Karate, they yell when kicking or hitting. read more