Fuel gallery residence time & heat transfer experimental technique development for gas turbine fuel injectors

Two experimental techniques are presented in this paper looking at flows in complicated passages such as those of internal fuel galleries in modern fuel spray nozzles. The first relates to residence time measurement using a dye wash-out technique and the second to surface heat transfer measurement using thermochromic liquid crystals. Dye concentration can be sufficiently calibrated making this technique easily and successfully applicable to residence time measurement within the chosen geometry. This experiment highlighted areas within the geometry where fuel is likely to become trapped in a recirculation and so leading to high residence times. The liquid crystal method proved more challenging due to the susceptibility of the crystals to fail under water. One set of measurements was gathered and showed that areas of high fuel residence time also correspond to low heat transfer coefficient. Small volumes of slow or stagnant fuel will be susceptible to soaking more heat increasing the risk of coke formation.