1.16. ENGINE TERMINOLOGY
Engine terminology must be explained at this point to enable you to understand the terms used in discussing gas-turbine-engine operating theory explained in this course. Directional references are shown in figure 1.9. Table I shows engine symbols and abbreviations commonly used.
Figure 1.9. Directional References.
Table I. Commonly Used Gas Turbine Engine Symbols and Abbreviations
- Directional references. Front or forward -- cold end of engine. Rear or aft -- hot end of engine. Right and left -- determined by viewing the engine from the rear. Bottom -- determined by the location of the combustor drain valve. Top -- directly opposite, or 180 degrees from the combustor drain valve. These directional references hold true for most gas turbine engines. On some the power shaft is at the end where the exhaust gas is expelled. An engine of this design is the T73 installed on the CH-54 flying crane.
- Engine station notation. The engine is divided into stations to designate temperature (T) or pressure (P) measuring locations. Figure 1.10 shows a T53-L-13, labeling the engine stations. Any time a number is placed after the letter T or P, it denotes a specific location in the engine.
Figure 1.10. Engine Stations.
Example: The symbol T3, denotes the relative temperature at a specific location on the engine.
- Engine speed notation. The rotational speed of the engine is represented by the capital letter N. The first rotating mass, the gas producer has the symbol N1. Any time a number is placed after the letter N it denotes a specific system on the gas turbine engine.