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The engine pressure ratio (EPR) is the total pressure ratio across a jet engine, measured as the ratio of the total pressure at the exit of the propelling nozzle divided by the total pressure at the entry to the compressor. [1] Jet engines use either EPR or compressor/fan RPM as an indicator of thrust. [2]
The flow of oil and the pitch are controlled by a governor, consisting of a gear type pump speeder spring, flyweights, and a pilot valve. The gear type pump takes engine oil pressure and turns it to a higher pressure which is in turn controlled in an out of the propeller hub by the pilot valve, which is connected to the flyweights, and a seeder ...
A separate actuator on the piping releases pressure in the line if it crosses a threshold. This releases the pressure on the back of the seal, causing the valve to open. The essential parts of a PORV are a pilot valve (or control pilot), a main valve, a pilot tube, the dome, a disc or piston, and a seat. The volume above the piston is called ...
Engine pressure ratio (EPR) differs from OPR in that OPR compares the intake pressure to the pressure of the air as it exits the compressor, and is always greater than 1 (often very much so), whereas EPR compares the intake pressure to the pressure at the engine's tailpipe (i.e., after the air has been used for combustion and given up energy to ...
A relief valve DN25 on cooling water pipe from heat exchanger Schematic diagram of a conventional spring-loaded pressure relief valve. A relief valve or pressure relief valve (PRV) is a type of safety valve used to control or limit the pressure in a system; excessive pressure might otherwise build up and create a process upset, instrument or equipment failure, explosion, or fire.
With traditional fixed valve timing, an engine will have a period of "valve overlap" at the end of the exhaust stroke, when both the intake and exhaust valves are open. The intake valve is opened before the exhaust gases have completely left the cylinder, and their considerable velocity assists in drawing in the fresh charge. Engine designers ...
In the event that pressurizer pressure exceeds a certain maximum, there is a relief valve called the pilot-operated relief valve (PORV) on top of the pressurizer which opens to allow steam from the steam bubble to leave the pressurizer in order to reduce the pressure in the pressurizer. This steam is routed to a large tank (or tanks) in the ...
A full authority digital engine (or electronics) control (FADEC) is a system consisting of a digital computer, called an "electronic engine controller" (EEC) or "engine control unit" (ECU), and its related accessories that control all aspects of aircraft engine performance.