Development of Pyro Igniter for Gas Turbine Engine Application

Abstract

As the initiation of ignition of gas turbine combustor is relying on conventional spark plug methods, it has some limitations at fuel lean mixture conditions, turbulence streams and high altitude relight conditions. Severely reduced spark plug performance and durability is an unfortunate consequence as engines are simultaneously being pushed to higher power densities and leaner stoichiometry in order to improve efficiency and lower emissions. However, an important parameter is the ignition under extreme conditions, lean combustible mixture and high initial pressure, requiring high voltage when using conventional spark plug technology and also significantly reduces the lifetime. An alternative solution to standard spark plug is the use of pyro materials to igniter applications. The overall energy conversion efficiency from chemical energy to electrical energy and mechanical energy will be less when compared to direct conversion of chemical energy to the required applications. Also, the pyro type sources are compact in size. In the gas turbine the exploitation of pyro igniter is inevitable. This research paper involves the demonstration of chlorine free propellant formulation, burning rate studies, application and compatibility of pyro igniter to initiate the ignition of gas turbine combustor. Ammonium Nitrate (AN) plus polymer binder (Hydroxyl Terminated Poly Butadiene – HTPB) and Ammonium Dichromate (ADC) catalyst based composite propellant pyro igniter material have been considered. This composite propellant delivers comparatively low performance, low temperature and low burn rate when compared to Ammonium Perchlorate (AP) based propellant. But AP based propellants discharges corrosive (HCl) gases. AN based composite propellant have chosen for the clean exhaust and non-toxic gases. The impact sensitivity of AN based propellant is quite normal comparable with AP based compositions and low when compared to double based propellants. The burning rate of the propellant is measured in 10 to 60 bar pressure range. The pyro igniter is fabricated and ignition tests are conducted. Average energy release rate of the pyro igniter is 16.6 KJ/s in the designed configuration.