Bristol Aero Engines. Rolls Royce Olympus

Design

A [Vous devez être inscrit et connecté pour voir ce lien] draws air in at the front and compresses it.

The air then combines with fuel and the engine burns the resulting mixture.

The combustion greatly increases the volume of the gases which are then exhausted out of the rear of the engine.

The Olympus engine took this gas jet and passed it through straightening vanes - to remove swirl.

This gas jet then entered the afterburning jet pipe where a ring of fuel injectors sprayed fuel onto the hot exhaust gases.

The resulting combustion greatly improved thrust, although it also led to high fuel consumption.

The afterburner was thus only used at takeoff and from just below Mach 1 up to Mach 1.7, the engine [Vous devez être inscrit et connecté pour voir ce lien] above that speed.

The afterburning section was longer than the engine itself (as was the case with all early turbojets) but the thrust of the Olympus 302 rose to 30,610 lbf (136 kN).

Inlet system

Although not strictly considered part of the engine, the variable engine inlet system was vital to the Olympus 593 on Concorde as supersonic airflow at the engine face could create shock waves that would lead to engine surge and failure.

The intake featured variable ramps which altered the intake area which slowed the intake air from [Vous devez être inscrit et connecté pour voir ce lien] to [Vous devez être inscrit et connecté pour voir ce lien] speed.

This was achieved by positioning the ramps such that shock waves were created at the inlet, air passing through these shock waves was slowed.

The inlet air was further decelerated as the intake area increased closer to the engine (speed of air flow decreases as area increases.)

During takeoff, when the engine's air demand was high, the ramps were flat at the top and the auxiliary flap was in, allowing more air to enter the engine.

As the aircraft approached Mach 0.7, the flap closed; at Mach 1.3, the ramps came into effect, removing air from the engines which was then used in the pressurisation of the cabin.

At Mach 2.0, the ramps had covered half their total possible distance.

They also helped reduce the work of the compressors by compressing the air and increasing air temperature as a fortunate byproduct of their function.

Any excess air was expelled through doors on the underside of the [Vous devez être inscrit et connecté pour voir ce lien] and some intake air was bypassed around the engine and mixed with the exhaust - to increase thrust and keep the engine cool.

The TSR-2 had used a semicircular design with the shock front adjusted by a translating centrebody to overcome the same problem.
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In order to achieve the necessary accuracy in the control of the intake ramp and spill positioning, it was found necessary to use a digital signal processor in the Air Intake Control Units.

This was developed relatively late in the programme (~1972) but proved successful in ensuring Concorde's fuel economy for transatlantic flights.

The digital processor also accomplished the task of accurately calculating the necessary engine spool speed scheduling to ensure an adequate margin in avoiding potentially damaging engine surge under all engine and airframe operating conditions.

The [Vous devez être inscrit et connecté pour voir ce lien] of the air by the inlet system as well as the compression within the engine was as high as 80:1 at supersonic speeds.

This gave the engine world-beating efficiency.^{[Vous devez être inscrit et connecté pour voir ce lien]}

Compression section

The engine is a twin spool engine with 7 compressor stages on each spool.

Unusually, the last 4 compressor stages were made of nickel alloy due to the high pressures and thus high temperatures in supersonic flight- ordinarily, nickel alloy is only used on the turbine sections of jet engines.

Exhaust nozzle

The variable geometry exhaust nozzle consisted of two "eyelids" which varied their position in the exhaust flow dependent on the flight regime, for example when fully closed (into the exhaust flow) they acted as thrust reversers, aiding deceleration from landing to taxi speed.