【名词&注释】
热效率(thermal efficiency)、柴油机(diesel engine)、实践证明(practice shows that)、废气涡轮机、手提式(portable)、照明灯(lighting lamp)
[单选题]废气涡轮机理想循环的热效率与( )有关。
A. 压气机的进口温度
B. 压气机的出口温度
C. 燃气的最高温度
D. A+B
查看答案&解析
举一反三：
[单选题]手提式(portable)防爆电池照明灯(lighting lamp)应至少能连续使用( )。
A. 5h
B. 4h
C. 3h
[单选题]第二组Displacement pumps are those where the volume of the pump chamber is alternately increased to draw the liquid in from the suction pipe and then decreased to force the liquid out into the delivery pipe. Centrifugal pumps are those wherein an impeller rotating at high speed throws the liquid by centrifugal force from the center to the periphery of the impeller where the liquid is discharged through the delivery outlet.
A. Gear pump consists of two or more meshing gears (spur, single or double helical teeth) enclosed m a close-fitted housing. These are used extensively for pumping fuel oil, lubricating oil and hydraulic oil. When gears are unmeshed on the inlet side, a pressure drop occurs that helps the atmospheric pressure acting on the surface of the oil in the reservoir to force it up the pipe to fill the void, the oil is then transferred around the periphery of the pump housing. As the gear teeth mesh again on the outlet side, they form. a seal that prevents oil from backing up to the inlet, the oil in the void is then be forced out into the discharge line.
B. All vane pumps have a rotor driven within a ring (cam ring) by a drive shaft coupled to a prime mover. A cylindrical rotor with sliding vanes, generally in radial slots, rotates within the ring. The center of the rotor is offset from the center of the ring. In a simple vane pump, as the rotor turns, the vanes are forced outward against the inner surface of the cam ring by centrifugal force. This outward radial movement of the vanes and turning of the rotor causes the chamber between the vanes to increase as the vanes pass further away from the inlet port. This increase in volume results in a lowering of pressure until the atmospheric pressure is sufficient to force oil from the reservoir into the inlet chamber. Oil from the inlet is swept away by the vanes toward the outlet port through a decreasing series of chambers until it is forced through the outlet port. A vane pump of balanced design has an elliptical cam ring so that two pumping chambers are formed. This pump is in hydraulically balance, since the two intake and two outlet ports are diametrically opposed to each other. Therefore the side loads exerted on the rotor cancel out, thereby increasing bearing lift and permitting high operating pressure.
C. According to the last sentence of paragraph 1, from where the liquid is discharged through the delivery outlet?
D. from the eye of the impeller
E. from passage of impeller
F. from the periphery of the impeller
G. from the impeller
[单选题]在雷雨即将来临时，货物的装卸必须()。
A. 停止
B. 减速
C. 加快
[单选题]实践证明，在长裙活塞上不设承磨环将会导致柴油机磨合运转中产生_______故障
A. 失中
B. 磨损
C. 过热
D. 拉缸
本文链接：https://www.zhukaozhuanjia.com/download/lx8eey.html
