During the static testing of a single spool turbojet engine (400 N Titan Engine) running on Jet A-1 as fuel, the startup sequence failed, however, the engine started successfully upon changing the fuel to diesel. Till that point, the engine was running successfully and a series of tests were conducted for about 5 hours. The ambient temperature varied from 15 ^0^C (winter) to 37 ^0^C (summer) and relative humidity varied from 40% to 90%. The start sequence failed at the maximum temperature (35 ^0^C) and moderate humidity conditions (50%). In this manuscript, the starting sequence is investigated using the measured parameters which include pressure, temperature, rotor speed and mass flow rate. The data was recorded using the computer-based data acquisition system from National Instruments^®^~­~.

During the starting sequence, the rotor speed is required to follow a path reaching the calibration speed for the successful start sequence. However, during the actual testing, after the engine reaches \~80% of the calibration value, a sudden drop in the rotor speed is observed. This sudden drop in rotor speed is followed by the surge of the compressor and flameout in the combustion chamber.

The data suggests that, as the rotor speed reaches \~80% of the calibration value, there is significant drop in the combustion efficiency which results in reduction of the net shaft power available (negative). This decrease in net shaft power reduces the shaft speed to which the engine control system responds by increasing the fuel flow rate. After this, the compressor operation moves towards the surge region (as suggested by dynamic pressure measurement) followed by flameout. However, the engine started successfully upon changing the fuel to diesel (from Jet A-1) which has different properties from Jet A-1.

Based on this, it is asserted that the ambient conditions in addition to the fuel properties affect the combustion behavior (in terms of efficiency), especially during the engine transients.


Analysis of Failed Startup Sequence of a Single Spool Turbojet Engine

Division / Sponsor:
International Gas Turbine Institute (IGTI)

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2020/volume/84058

Turbo Expo - Virtual Conference

Supporting the need among researchers worldwide for additional online and multimedia content, ASME now offers the ASME Conference Video Collection. This platform will collect and provide long-term access to conference presentation videos, encompassing all technology areas within ASME's technical conference and events program. About 30,000-40,000 engineers across all mechanical engineering and related disciplines participate in ASME conferences each year. This includes authors of approximately 6,000 to 8,000 technical papers published by ASME, the majority of whom also submit video presentations for our virtual conferences. The video collection will be available as an add-on to existing product packages or as a separate subscription.