want to read about : Controls and instrumentation - INSTRUMENTATION
Engine thrust
10. The thrust of an engine is shown on a thrust- meter, which will be one of two basic types; the first measures turbine discharge or jet pipe pressure, and the second, known as an engine pressure ratio (E.P.R.) gauge, measures the ratio of two or three parameters. When E.P.R. is measured, the ratio is usually that of jet pipe pressure to compressor inlet pressure. However, on a fan engine the ratio may be that of integrated turbine discharge and fan outlet pressures to compressor inlet pressure.
11. In each instance, an indication of thrust
output is given, although when only the turbine discharge pressure is
measured, correction is necessary for variation of inlet pressure;
however, both types may require correction for variation of ambient
air temperature. To compensate for ambient atmospheric
conditions, it is possible to set a correction figure to a
sub-scale on the gauge; thus, the minimum thrust output can be checked
under all operating conditions.
12. Suitably positioned pilot tubes sense the pressure or pressures appropriate to the type of indication being taken from the engine. The pilot tubes are either directly connected to the indicator or to a pressure transmitter that is electrically connected to the indicator.
13. An indicator that shows only the turbine discharge pressure is basically a gauge, the dial of which may be marked in pounds per square inch (p.s.i.), inches of mercury (in. Hg.), or a percentage of the maximum thrust.
Engine thrust
10. The thrust of an engine is shown on a thrust- meter, which will be one of two basic types; the first measures turbine discharge or jet pipe pressure, and the second, known as an engine pressure ratio (E.P.R.) gauge, measures the ratio of two or three parameters. When E.P.R. is measured, the ratio is usually that of jet pipe pressure to compressor inlet pressure. However, on a fan engine the ratio may be that of integrated turbine discharge and fan outlet pressures to compressor inlet pressure.
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| Fig. 12-3 Electro-mechanical E.P.R. transmitter. |
12. Suitably positioned pilot tubes sense the pressure or pressures appropriate to the type of indication being taken from the engine. The pilot tubes are either directly connected to the indicator or to a pressure transmitter that is electrically connected to the indicator.
13. An indicator that shows only the turbine discharge pressure is basically a gauge, the dial of which may be marked in pounds per square inch (p.s.i.), inches of mercury (in. Hg.), or a percentage of the maximum thrust.
