时间：2011-03-11 23:18来源：蓝天飞行翻译 作者：航空 点击：次
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scavenger pump (lubrication system). A pump in a dry sump lubrication system that picks up the oil after it passes through the engine and returns it to the oil tank. Scavenger pumps have a larger capacity than pressure pumps, because the oil being returned is hot and contains air. Both conditions increase its volume. schematic diagram. A diagram of an electric or fluid power system in which the components are represented by symbols, rather than drawings or pictures of the actual devices. Schematic diagrams are used for troubleshooting. Schrader valve. A spring-loaded service valve used in an air conditioning system. A Schrader valve is much like the valve used to put air into a tire. scientific notation (mathematics). A mathematical time saver used when working with very large and very small numbers. When using scientific notation, all numbers are changed into a positive number between one and 10 by moving the decimal point and attaching the number ten, raised to the power showing the number of places the decimal has been moved. A negative (minus) number is used if the decimal was moved to the right, and a positive number is used if it is moved to the left. Using this system, 1,000 = 1 · 103, and 0.001 = 1 · 10-3. scimitar shape. The shape of the blades of the propellers mounted on an unducted-fan engine. The name is taken from the shape of a curved Asian sword that has its edge on the convex side. scissors (landing gear component). A name commonly used for landing gear torque links. See torque links. score (mark). A scratch across a piece of material made to cause the material to break along the line. When a piece of glass is to be cut with a glass cutter, it is scored by scratching through its surface with the cutter. When the glass is bent, all of the stresses concentrate in the scored line, and the glass breaks along the line. SCR (silicon controlled rectifier). A reverse-blocking triode thyristor that can be triggered into conduction in only one direction. The three terminals of an SCR are the anode, the cathode, and the gate. An SCR blocks electron flow in both directions until a pulse of electrical energy of the proper polarity is applied to the gate. The SCR will then conduct electrons in its forward direction, between its cathode and its anode. A conducting SCR will continue to conduct until the voltage across the anode and cathode is removed or until its polarity is reversed. See thyristor. scramjet (supersonic combustion ramjet). A special type of ramjet engine whose fuel can be ignited while the vehicle is moving at a supersonic speed. See ramjet engine. screeching (gas turbine engine operation). A condition of combustion instability in a gas turbine engine or afterburner. The combustion produces a shrill, high-pitched noise. |
