时间：2011-03-11 23:11来源：蓝天飞行翻译 作者：admin 点击：次
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compression tester (differential). A maintenance tool used to determine the functional condition of a reciprocating engine cylinder. A regulated air pressure of 80 psi is directed into the cylinder through a calibrated orifice, and the pressure is measured on both sides of the orifice. The difference between the indications on the two gages is the pressure drop across the orifice. This drop is caused by air leaking past the piston rings or the valves. Typically, a cylinder should hold 75% of the air pressure applied to it. Therefore the cylinder pressure gage should read at least 60 psi when the input pressure gage reads 80 psi. compression wave (high-speed aerodynamics). A shock wave which forms on the surface of an airfoil moving through the air at a speed greater than the speed of sound. compression wood. The defect in wood which causes it to have a high specific gravity and the appearance of an excessive growth of summerwood. In most species, there is little difference between the color of the springwood and summerwood. Any material containing compression wood is unsuited for aircraft structural use and must be rejected. compressive load (compressive stress). A physical load, or stress, which tries to squeeze together the ends of the object on which it acts. compressive strength. The ability of an object to resist a compressive load. Compressive strength resists the force that tries to squeeze the ends of an object together. compressor (air conditioning system component). The component in a vapor-cycle cooling system in which the low-pressure refrigerant vapors, after they leave the evaporator, are compressed to increase both their temperature and pressure before they pass into the condenser. Increasing the temperature of the refrigerant allows it to give up some of its heat energy to the air flowing through the condenser. Some compressors are driven by electric motors, others by hydraulic motors and, in the case of many light airplanes, are belt driven from the engine. compressor (gas turbine engine component). The section of the gas turbine engine whose components increase the pressure of the air flowing through it. compressor blade (gas turbine engine component). A rotating airfoil installed on the disk of a compressor in a gas turbine engine. A compressor blade adds energy to the air as it moves through the engine. compressor bleed air (gas turbine engine). Air that is tapped off from a turbine engine compressor and used for anti-icing the inlet ducts and cooling the turbine inlet guide vanes and first stage turbine blades. Bleed air may also be dumped to relieve internal pressure and prevent a compressor stall. Compressor bleed air may also be used for such airframe functions as pressurization and the operation of some of the components in the pneumatic system. See customer bleed air. compressor case (gas turbine engine component). The outer housing of the compressor section of a gas turbine engine. In an engine using an axial-flow compressor, the stator vanes are mounted in the compressor case. |
