|M.Sc Student||Gordana Roni|
|Subject||High Altitude Ignition Process in Small Jet Engine|
|Department||Department of Aerospace Engineering||Supervisor||Professor Emeritus Yeshayahou Levy|
Manned and unmanned flight vehicles that are propelled by small gas turbine engines are limited in their flight altitude mainly by the low air densityand the low temperature of the air that exists at high altitude. The present work is concerned with solutions forthe ignition problem in small gas turbine engines using vaporizers. The solution that was implemented consisted of two types of sprayers: “Air Blast” and “Air Assist”. The mechanism that was developed, included design and manufacturing several accessories that assists toinvestigate the effect of the spray form and drop size distribution. Quantitative measurements of the droplet’s diameter performed usingPDA (Phase Doppler Analyzer) facility, while investigating the influencing factors. Within the controlled parameters inside the combustion chamber it was found that the “assisting air” has a paramount influence on the size of the drops. The effect of preheating and also the measurement distance from the vaporizer edge were investigated. The experimental testing was concluded with thesystem beingintegrated into a combustion chamber segment of an engine in order to investigateignition possibility in practical fuel and air-flow conditions. The ignition process took only several milliseconds. The research helped to implement the theory while combining two different spraying methods unified as a common system. The design solution is not expected to affect the steady stateoperation of the combustor in the engine where fuel is vaporized using vaporizers. The system has potential for increasing reliability that is critical for the engine activity and for the mission success.