Olympus - Small Jet Engine

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The test cell was designed to support educational activities in the field of gas turbines. The design was undertaken by a student, as part of his requirements for obtaining a mechanical engineering degree. The test cell consists of: the enclosure, the test engine, the exhaust duct and the control panel.

The test engine is a small turbojet named Olympus by Netherlands’ Micro Turbines Company. This engine is used for the propulsion of radio controlled aircraft models. It consists of one-stage radial flow compressor, annular combustor and one-stage axial flow turbine. The fuel is heating petrol. Lubricant is mixed with the fuel, for the rotating parts lubrication and especially the two single ball bearings that support the engine spool.

The operation is controlled by a microprocessor called ECU (Engine Control Unit), which constantly reads EGT (Exhaust gas Temperature) and Shaft speed. Also there is an automatic start unit (ASU), controlled by ECU, which performs startup and shutdown steps. The engine speed up is achieved using pressurized air. Although the basic fuel is petrol, the ignition and warm-up of the engine are necessarily done with propane. This is because at low shaft speeds, petrol atomization is impossible and there is no combustible mixture. When the EGT reaches a certain value or shaft speed is high enough for appropriate air compression, the fuel pump starts feeding with petrol and propane and air valves close.

Several measurements along the engine are taken using appropriate instrumentation. Thermocouples are used for temperature measurements. Also static pressures are measured through wall taps and pressure transducers. The instruments provide analog voltage outputs which are fed to a computer with the aid of an analog-to-digital converter.